Cold Hands Research Articles

Effects of local and core body temperature on grip force modulation during movement-induced load force fluctuations

Impaired manual functioning often occurs when the hands are exposed to cold temperatures, but the underlying mechanism is not clearly understood. Tactile feedback is thought to provide important information during object manipulations in order to scale and regulate grip forces; however, topical anaesthetic-induced tactile sensation impairments may not realistically simulate the systemic neuromuscular impairment of the whole hand that could occur during cold temperature exposure. In two experiments, we studied the impact of (1) local hand cooling [thermoneutral finger skin temperature, cold (<8 degrees C)] and (2) core body temperature (thermoneutral core body temperature, pre-heated by 0.5 degrees C, pre-cooled by 0.5 degrees C) with cold hands on manual dexterity and the ability to control and co-ordinate grip forces during a cyclical load-lifting task. In Experiment 1 (n = 10), hand cooling significantly decreased Purdue Pegboard performance (P = 0.002), while increasing grip force by approximately 5 N during the cyclical load-lifting task compared to thermoneutral (P = 0.037). The temporal co-ordination of grip and load forces was unaffected by hand cooling. In Experiment 2 (n = 11), pegboard performance was impaired following hand cooling (P < 0.001), and to a greater extent when the body was pre-cooled (p < 0.001). However, neither grip force (P = 0.99) nor the temporal co-ordination of grasping and lifting forces (P = 0.85) were affected by core body temperature. These data support the existence of a robust centrally controlled feedforward system able to anticipate the dynamics of manual manipulations and accordingly regulate the temporal co-ordination of fingertip forces during object manipulation. This centrally controlled mechanism appears to differ from the mechanisms governing other aspects of manual dexterity.

Comparative Study of Femineral® and Floradix® in Women of Child-Bearing Age and Adolescent Girls with Iron Deficiency Anaemia

This double blind randomised trial compared the clinical efficacy of Femineral®, a proprietary herbal preparation containing highly soluble iron compounds, minerals, and vitamins, with Floradix®, the most popular iron supplement in Scandinavia for patients with iron deficiency anaemia (IDA). Fifty women of childbearing age and adolescent girls, all diagnosed with IDA, were randomised into two groups. One group (n = 26) was treated with Femineral (10 ml twice a day; 15 mg of iron supplement/day), while the second (n = 24) received Floradix® (10 ml twice a day; 20 mg of iron supplement/day). The efficacy of 28 days of treatment in each group was evaluated by analysis of serum iron levels, blood haemoglobin and erythrocyte counts; by the mental performance of the patients on days one and 28; and by assessment of IDA symptoms, such as pale skin colour, fatigue, irritability, weakness, constipation, brittle nails, cold hands and feet, headache, blue tinge to sclera, and feeling of well being on days one, seven, 14 and 28. The Femineral group showed significant improvements in blood haemoglobin levels and red cell counts after 28 days, while the Floradix group did not. The Femineral group showed better improvements in other IDA symptoms, such as impaired mental performance, pale skin colour, fatigue, irritability, weakness, constipation, brittle nails, cold hands and feet. Both groups showed significant improvements in serum iron levels at the end of the study. Such improvements correlate with the results of memory tests: the number of errors by both groups was significantly lower at the end of the study. There were no significant differences in memory tests between the two groups. Eight patients in the Floradix group and one in the Femineral group reported drowsiness. The Femineral group reported two other adverse events (nausea and vomiting). Femineral can be used safely in the treatment of iron deficiency anaemia. It is more efficient and safe than Floradix.

Can scorpions be useful?

At 1000 h on June 14, 2005, a 10-year-old boy, breathless and cold, was brought to our hospital by his father. The father reported that at 2000 h, the boy had been stung by a red scorpion—causing excru ciating pain, which decreased in the following hour, as an ice pack was applied to the site. However, the boy then vomited twice, and started to sweat profusely. The father took the boy to the village tantrik (traditional healer), who recited a healing spell. By 0230 h, the boy’s hands and feet were cold, and he felt short of breath. He was unable to sleep. The father car ried his son 2 km to the nearest road, and then travelled the remaining 46 km to hospital by hired autorickshaw. On arrival, the boy was propped up, and given supplementary oxygen. The pulse was weak; the electrocardiogram (ECG) showed a heart rate of 188 beats per min. The systolic blood pressure and respiratory rate were 70 mm Hg and 60 breaths per min respectively. A loud summation gallop was heard over the praecordium; bubbling, low-pitched crackles were heard all over the chest. Priapism was noted. The boy was given furosemide 20 mg intravenously, a slow bolus of aminophylline 50 mg, and prazosin 250 μg orally. He was also given a 12-h infusion of dobutamine, at 10 μg/kg per min. The pulmonary oedema resolved within 12 h, and the tachycardia within 36 h. Blood tests showed normal electro lyte concentrations. However, between 36 h and 60 h after admission, although the patient had no fever, the ECG showed a pattern diagnostic of Brugada syndrome— with raised, upwardly convex ST segments descending into inverted T waves in leads V1–V3 (fi gure). This pattern had resolved by 72 h; the patient was discharged on June 18, 2005, with a systolic blood pressure of 110 mm Hg, and a heart rate of 75 beats per min. Although the patient was treated free of charge, and the family was off ered a day’s earnings and free transport to attend, they declined follow-up. The patient was visited at home in October, 2007, and was well, with a normal ECG. Brugada syndrome is an inherited disorder characterised by ST-segment elevation in the right praecordial leads, and associated with sudden cardiac death. 10–30% of cases are caused by mutations in the SCN5A gene, on chromosome 3, which codes for the α-subunit of the cardiac voltage-dependent sodium channel. Mutations usually reduce the sodium current. Brugada syndrome can sometimes be unmasked by the administration of a sodium-channel blocker, such as ajmaline. In this case, Brugada syndrome may have been serendipitously unmasked by scorpion toxin. Toxin from scorpions such as Mesobuthus tamulus (the Indian red scorpion) activates sodium channels and inhibits potassium channels— leading to intense and persistent depolarisation of autonomic nerves. The resulting autonomic storm is characterised by transient parasympathetic (vomiting, sweating, priapism, hypotension, cardiac dysrhythmias) and prolonged sympathetic (hypertension, tachycardia, cold hands and feet, pulmonary oedema, shock) features. Scorpion envenoming is therefore treated with prazosin, a postsynaptic α blocker—even though at present an intravenous preparation of this drug is not available. I postulate that in this patient, the initial surge in sodium current depleted intracellular sodium, and caused Brugada syndrome to manifest later—although ECG patterns diagnostic of Brugada syndrome can appear intermittently, even without a drug challenge. Perhaps drugs derived from scorpion toxin could increase the sodium current, and treat Brugada syndrome.

The thermophysiological cascade leading to sleep initiation in relation to phase of entrainment

This article reviews circadian thermoregulation in relation to sleep induction and phase of entrainment in the light of the comprehensive thermophysiological and chronobiological concepts of Jürgen Aschoff. The idea that temperature and sleep are interrelated is based on evolutionary history. Mammalian sleep developed in association with endothermy, and all species, independent of temporal niche, usually sleep during the circadian trough of their core body temperature (CBT) rhythm. The circadian pattern of CBT results from the balance between heat production and heat loss, the latter being relevant for sleep induction. Sleep under entrained conditions is typically initiated on the declining portion of the CBT curve when its rate of change and body heat loss is maximal. Body heat loss before lights off, via selective vasodilatation of distal skin regions, promotes sleepiness and the rapid onset of sleep. This thermophysiological effect represents the cement between the circadian clock and the sleep-wake cycle, and in turn determines phase of entrainment (Psi) and sleep onset latency (SOL). These interrelationships have been recently studied in a particular subset of the general population, mainly women, who suffer from cold hands and feet (the so-called vasospastic syndrome, VS). Women with VS exhibit not only a lower capacity to lose heat during the daytime but also a prolonged SOL, a disturbed Psi of the circadian clock with respect to the sleep-wake cycle and psychologically, a disposition to turn experienced anger inwards. This naturalistic model leads us to a more general conclusion that regulation of distal skin blood flow may have clinical relevance for insomnia, in particular sleep onset insomnia.

Cold hands, headache and chest pain

Cold hands, headache and chest pain

Gender, genotype, and phenotype differences in Smith–Magenis syndrome: a meta‐analysis of 105 cases

Smith-Magenis syndrome (SMS) is a multisystem disorder characterized by developmental delay and mental retardation, a distinctive behavioral phenotype, and sleep disturbance. We undertook a comprehensive meta-analysis to identify genotype-phenotype relationships to further understand the clinical variability and genetic factors involved in SMS. Clinical and molecular information on 105 patients with SMS was obtained through research protocols and a review of the literature and analyzed using Fisher's exact test with two-tailed p values. Several differences in these groups of patients were identified based on genotype and gender. Patients with RAI1 mutation were more likely to exhibit overeating, obesity, polyembolokoilamania, self-hugging, muscle cramping, and dry skin and less likely to have short stature, hearing loss, frequent ear infections, and heart defects when compared with patients with deletion, while a subset of small deletion cases with deletions spanning from TNFRSF13B to MFAP4 was less likely to exhibit brachycephaly, dental anomalies, iris abnormalities, head-banging, and hyperactivity. Significant differences between genders were also identified, with females more likely to have myopia, eating/appetite problems, cold hands and feet, and frustration with communication when compared with males. These results confirm previous findings and identify new genotype-phenotype associations including differences in the frequency of short stature, hearing loss, ear infections, obesity, overeating, heart defects, self-injury, self-hugging, dry skin, seizures, and hyperactivity among others based on genotype. Additional studies are required to further explore the relationships between genotype and phenotype and any potential discrepancies in health care and parental attitudes toward males and females with SMS.

Hand Skin Temperatures Associated with Local Hand Discomfort under Whole-body Cold Exposure

This study aimed at pointing out the local thermal effects and subjective responses to cold air exposures of gloved hands in conditions of similar hand heat loss rates. Thirteen males and 13 females, lightly clothed (0.6 clo), participated in three separated experimental sessions (once a week), while sitting for 105 min in a climatic chamber at an operative temperature of 19°C. Subjects' hands were exposed in a ventilated cold box (air velocity=2.5 m·s−1) at one of three temperatures (8°C, 10°C or 14°C) depending on the dry heat exchange coefficient of the gloved hands. The temperature of the box was chosen to induce similar heat loss rates across conditions. Main results showed that local skin temperatures can be divided in 3 categories: 4 fingers (coolest), a thumb, back and palm (least cool). Female had lower skin temperatures than males but their local thermal discomfort was found to be similar for the same local skin temperature levels. As a consequence, the durations of the accepted exposures without discomfort were shorter in females. Discrepancies between male and female responses are discussed in terms of different hand skin blood flows. A practical aspect of our results concerns the glove thermal insulations which are obviously too poor at the finger levels, a factor determinant for discomfort occurrence in case of cold hand exposures.

Strategies to combat heat strain during and after firefighting

The use of phase change cool vests during firefighting and the efficacy of 20 min cold water hand immersion following such activity was investigated. Core temperature was unaffected by cool vest wear, as was skin temperature, sweat rate and heart rate, and cannot be recommended for use. There was a trend for core temperature decline to be accelerated by hand immersion after 10 min, but this trend disappeared after 20 min. Hand immersion had no substantive effect on core temperature attenuation in firefighters who had partially removed their clothing, consumed cold water and sat in a cool and ventilated room.

The patient with cold hands Understanding Raynaudʼs disease

The availability of new treatments for Raynaud's disease, as with any medical condition, depends on how convincing the results of clinical research prove to be. The validity and reliability of research in Raynaud's disease is subject to two major constraints: the seasonal and intermittent nature of the condition limits the amount of time patients can be studied continuously, and researchers have failed to agree on objective outcome measures. Vascular physiology is, and no doubt is destined to remain, a dynamic and technology-driven clinical realm. Despite the wide array of promising treatments, the best and most basic management of Raynaud's disease seems to be behavioral and at least partly pharmaceutical. The two biggest behavioral factors are nicotine use and exposure to cold environments. Giving up nicotine can be a daunting challenge for long-term smokers and chewing-tobacco users. Avoiding cold environments may be easier said than done, especially for patients who work outdoors or in air-conditioned spaces. Perhaps the best treatment for Raynaud's disease is a reliable diagnosis and the positive prognosis that comes with it. Most patients have a stable course, and nearly half will actually improve with time and steady reassurance.

Short-Term Retinal Vessel Diameter Variability in Relation to the History of Cold Extremities

To test whether the regularity and short-term changes of retinal vessel diameter are related to the history of cold hands and feet and to nailfold circulatory response to cooling. In 13 vasospastic and 13 nonvasospastic young healthy women (based on their history of cold extremities and nailfold capillaroscopy) 20- to 30-second recordings of the ocular fundus was obtained with a retinal vessel analyzer. The spatial regularity of arterioles and venules was analyzed by means of the coefficient of variation of vessel diameter and by exploratory Fourier analysis of spatial frequencies. Temporal variability was analyzed as excursion amplitude of the vessel diameter, as a correlation of means and standard deviations of vessel diameter within a defined time period, and by Fourier analysis of temporal diameter change in the heartbeat frequency range. Mean diameters of selected segments of arterioles (129.9 +/- 15.3 and 124.4 +/- 24.4 microm) and venules (150.8 +/- 14.6 and 149.3 +/- 19.6 microm) were not different between the vasospastic and nonvasospastic groups, respectively. Spatial variability: The coefficient of variation in arterioles was 8.8% +/- 2.8% and 6.1% +/- 1.7%, in venules 3.8% +/- 1.4%, and 3.6% +/- 0.9% in the vasospastic and nonvasospastic groups, respectively (difference by ANOVA, P = 0.017). Fourier analysis revealed differences between arterioles in the two groups, with relative Fourier power spectrum amplitudes of spatial frequencies higher in vasospastic eyes (Mann-Whitney P = 0.029). Temporal variability: The excursion amplitudes of vessel diameters were comparable in the two groups. Individual coefficients of correlation of successive means and standard deviations of the vessel diameter were 0.11 +/- 0.23 and 0.09 +/- 0.23 in the nonvasospastic group, and 0.25 +/- 0.40 and 0.24 +/- 0.22 in the vasospastic group, in the arterioles and venules, respectively (ANOVA: vasospastic versus nonvasospastic; P = 0.038). Fourier analysis in the heartbeat frequency range revealed differences in relative power spectrum amplitudes of temporal frequencies between arterioles in the two groups (higher in the vasospastic group, Mann-Whitney P = 0.029). Retinal arterioles in healthy vasospastic women show higher spatial irregularity and an increased vessel diameter variation within the temporal frequency of the heartbeat than do arterioles in nonvasospastic women.

Effect of cold acclimation on neuromuscular function of the hand

The research in this thesis investigated the effects of cold stress on neuromuscular function with the main focus on cold acclimation. In total, 6 studies, 1 field study and 5 experiments, were conducted. The field study showed that during manual work in cold weather, finger and hand temperature can drop to levels that may impair manual function. The first 2 experiments were conducted to investigate the effect of acute local cold stress on force control and to investigate the effect of cold-induced vasodilatation (CIVD) on neuromuscular function. In experiment 1, it was found that cooling of the hand in 10 °C cold water for 10 min did not improve force control, although neuromuscular function was significantly impaired after cooling. In experiment 2, cold-induced vasodilatation, occurring after 20 min of 8 °C cold-water immersion of the hand, was confined to the finger tip and had no effect on the temperature of the first dorsal interosseus (FDI) muscle or its neuromuscular function. A series of cold acclimation studies was conducted to investigate the effect of repeated cold-water hand immersions on neuromuscular function. In these experiments, neuromuscular function was tested before and after 2–3 weeks of daily hand immersion in 8 °C cold water for 30 min. In experiment 3, it was found that 3 weeks of cold-water immersion resulted in a decrease in minimum and mean index finger temperature and CIVD was attenuated. Neuromuscular function was not affected by this change in temperature response. In experiment 4, one hand was exposed daily to cold water and compared with the opposite control hand. Blood plasma catecholamine concentrations were increased after 2 weeks in the cold-exposed hand, but no changes in temperature response or neuromuscular function were found after repeated cold exposure. Thermal comfort after 30 min of cold-water immersion significantly improved after repeated cold exposure causing a discrepancy between actual and perceived temperature and it was suggested that this may impose a greater risk of cold injury owing to a change in behavioural thermoregulation. In the last experiment, core temperature was elevated by bicycling at a submaximal level during the cold hand immersion. Exercise had a direct effect on the temperature response during cold-water immersion, decreasing the minimum FDI temperature and slowing down the deteriorating effect of cold on neuromuscular function; however, exercise showed was no effect on local cold acclimation. It is concluded that local repeated cold exposures may improve finger and hand temperature and subjective thermal ratings, but that these changes are too small to improve neuromuscular function. The best remedy to maintain manual function is to limit or avoid cold stress as much as possible. If sufficient protection of the hands is impossible, core heating through exercise or passive heating may be a solution.

Immune function in acute stress

The aim of this study was to evaluate immune function in acute stress in medical students before academic examinations. Twenty-five medical students were selected because they presented intense acute stress, evaluated by the presence of the following classic signs: cold hands, intense sudoresis in the extremities, generalized sudoresis, paleness, tachycardia, confused reasoning, nervous irritability, diarrhea, and sleep disorders in the hours preceding the examination (agitated sleep, insomnia). Methods Immediately before the examination, peripheral blood was collected from the 25 students presenting acute stress to analyze T and B cells, CD4+ and CD8+ cells, immunoglobulins, and C3 and C4 complement components, as well as phagocytic activity in neutrophils and monocytes. These investigations were repeated in the same students in situations free of acute stress. The results of the two samples collected from each student were compared. Results The means and standard deviations showed no significant differences for any of the parameters analyzed (p ≥ 0.01). Conclusion We conclude that acute stress did not cause changes in the lymphocyte subpopulations, phagocytic activity of neutrophils and monocytes, serum immunoglobulins, or C3 and C4 complement components in students participating in the present study. In conditions of basal chronic stress, acute stress may cause alterations in immune function.

Steal in Hemodialysis Patients Depends on Type of Vascular Access

To study incidence and severity of steal phenomena in hemodialysis patients and to investigate possible methods for its detection. A questionnaire was composed based on a literature search. A subgroup of patients having steal as identified by the questionnaire was studied using physical examination, arterial blood pressure, skin temperature, digital oxygenation, grip strength and plethysmography. Contralateral arms served as controls. A cold hand was present in 50% of the patients with a brachiocephalic (BC) arteriovenous fistula (AVF, n = 28) compared to 25% of prosthetic forearm loops (loop, n = 27) and 12% of the radiocephalic (RC, n = 65, p < 0.05) fistulas. Diabetics were at risk for steal (p < 0.001). Intensity of steal was not related to magnitude of access flow. Digital skin temperatures and grip strength were lower in steal hands (p < 0.02). Manual compression of the AVF normalised low digital pressures in steal hands (106 +/- 33 vs 154 +/- 25 mmHg, p < 0.001, contralateral side 155 +/- 21 mmHg). Mild to moderate steal symptoms are common in a hemodialysis patient. Individuals with a BC are at a higher risk for developing complaints associated with reduced hand circulation compared to patients with a RC or loop. Low finger pressures in the presence of steal symptoms are usually reversible.

Residual Stress Solution Extrapolation for the Slitting Method Using Equilibrium Constraints

Established methods for calculating residual stresses from the strains measured when using the slitting method give results for the stresses that exist within the depth range of the slit. Practical considerations typically limit this range to about 90–95% of the specimen thickness. Force and moment equilibrium can provide additional information that may be used to estimate the residual stresses in the “no-data” region within the remaining ligament beyond the maximum slit depth. Three different numerical methods to calculate the residual stress profile over the entire specimen thickness are investigated. They are truncated Legendre series, regularized Legendre series, and regularized unit pulses. In tests with simulated strain data and with strain data measured on a cold compressed 7050-T7452 Aluminum hand forging, the three methods gave generally similar stress results in the central region of the specimen. At small depths, where the strain sensitivity to the residual stresses is low, the two regularized calculation methods tended to give more stable results. In the area of very large depth beyond the maximum depth of the slit, the regularized Legendre series solution generally gave the most realistic stress results.

Clinical recognition of meningococcal disease in children and adolescents

Meningococcal disease is a rapidly progressive childhood infection of global importance. To our knowledge, no systematic quantitative research exists into the occurrence of symptoms before admission to hospital. Data were obtained from questionnaires answered by parents and from primary-care records for the course of illness before admission to hospital in 448 children (103 fatal, 345 non-fatal), aged 16 years or younger, with meningococcal disease. In 373 cases, diagnosis was confirmed with microbiological techniques. The rest of the children were included because they had a purpuric rash, and either meningitis or evidence of septicaemic shock. Results were standardised to UK case-fatality rates. The time-window for clinical diagnosis was narrow. Most children had only non-specific symptoms in the first 4-6 h, but were close to death by 24 h. Only 165 (51%) children were sent to hospital after the first consultation. The classic features of haemorrhagic rash, meningism, and impaired consciousness developed late (median onset 13-22 h). By contrast, 72% of children had early symptoms of sepsis (leg pains, cold hands and feet, abnormal skin colour) that first developed at a median time of 8 h, much earlier than the median time to hospital admission of 19 h. Classic clinical features of meningococcal disease appear late in the illness. Recognising early symptoms of sepsis could increase the proportion of children identified by primary-care clinicians and shorten the time to hospital admission. The framework within which meningococcal disease is diagnosed should be changed to emphasise identification of these early symptoms by parents and clinicians.

What is known about temperature and complaints in the upper extremity? A systematic review in the VDU work environment

Upper extremity musculoskeletal complaints and disorders are frequently reported among visual display units (VDU) workers. These complaints include cold forearms, hands or fingers. The aim of this systematic review was to gain an insight into the relationship between objective and subjective temperature decrease and musculoskeletal disorders (MSDs) in the upper extremity in a VDU work environment by (internal or external) cooling of the arm and hand. Two questions were formulated: (1) Is a VDU work environment (temperature between 15 and 25 degrees C) associated with temperature decrease of the arm, hand or fingers in healthy subjects? (2) Is there a difference in arm, hand and finger temperature between patients with upper extremity MSDs and healthy subjects in a VDU work environment? Through a systematic literature search in six databases between 1989 and October 2005, 327 articles were retrieved and 17 included. Forearm, hand and finger temperature significantly decreases when the ambient temperature (between 15 and 25 degrees C) decreases. The skin temperature in the hand that uses a computer mouse is lower than the other hand in the same ambient temperature. At baseline, no objective temperature differences are found between patient groups and controls, whereas in patients with cold hand complaints, lower skin temperatures are found compared to controls. The association between temperature (changes) in the forearm, hand or fingers during VDU work, and MSDs in the upper extremity is not clear. There is no consistent evidence available for the association between upper extremity MSDs and temperature changes in forearm, hand or fingers in an office work environment.

Water-filled garment warming of infants undergoing open abdominal or thoracic surgery

We have assessed the efficacy of a water-filled garment (ThermoWrap-Allon 2001) to maintain normothermia in small infants during major open abdominal or thoracic surgery. Twenty-two patients were studied in a case-matched comparison of two methods of thermal control intended to maintain core body temperature at 37 degrees C. The standard method involved a warm air mattress with additional insulation. The ThermoWrap garment covered the head, trunk and legs and the water temperature was automatically controlled. Central and peripheral temperatures were recorded every 15 min. Nineteen infants had abdominal and three had thoracic operations. The mean weight was 3.2 kg (range 1.4-7.8 kg). Over time, the core temperature declined with standard care but not with the ThermoWrap. Core temperature was statistically lower in the standard care infants by 30 min after start of surgery. Six infants had a core temperature of less than 35 degrees C with standard care (lowest 33.7 degrees C); the lowest temperature with the ThermoWrap was 35.6 degrees C. Some infants had cold hands with the ThermoWrap. Core temperature is better preserved with the ThermoWrap; extra insulation of exposed arms may be necessary. An important advantage of the ThermoWrap is its ability to control body temperature automatically.

Autonomic Function in Children With Congenital Central Hypoventilation Syndrome and Their Families

Congenital central hypoventilation syndrome (CCHS) is a genetic disorder characterized by failure of automatic control of breathing in the absence of obvious anatomic lesions. There have been several reports suggesting that CCHS patients display autonomic dysregulation. Pulse arterial tonometry (PAT) is a novel technique that provides noninvasive moment-to-moment measurements of sympathetic tone changes to the cutaneous vascular bed. We hypothesized that autonomic function as measured by PAT would be altered in children with CCHS. Prospective study. CCHS Family Conference, Orlando, FL, and the local community in Louisville, KY. Nineteen CCHS patients and 31 parents as well as 24 control children and 15 adult control subjects. Children with CCHS and their parents underwent sympathetic challenges (vital capacity sigh and cold hand pressor test) and a test of reactive hyperemia (brachial artery occlusion) while PAT was continuously monitored from the right hand. Control children and control adults underwent the same procedure. The maximal change of the PAT signal compared to the preceding baseline was averaged and expressed as percentage change for each of the challenges. The magnitude of sympathetic discharge-induced attenuation of PAT signal following a sigh was reduced in CCHS children compared to control subjects for both the vital capacity sighs and the cold hand pressor test. There were no differences observed in the magnitude of PAT attenuation between parents of children with CCHS and control adults. No differences were observed between either CCHS and control subjects or CCHS parents and adult control subjects for the brachial artery occlusion test. CCHS patients show an attenuated response to endogenous sympathetic stimulation, supporting the presence of autonomic nervous system dysfunction as a consistent feature of this condition. No differences were found in parents of children with CCHS compared to control adults, consistent with the finding that CCHS is primarily the result of a de novo gene mutation.

Losers, Winners, and Biased Trades

When faced with sequential information, consumers tend to fall prey to one of two well-known heuristics: the hot (or cold) hand and the gambler's fallacy. The authors relate these two traditionally separate heuristics to differences in accepting (buy) versus rejecting (sell) decisions. They identify trend length as a contextual moderating variable and show an asymmetry between buying and selling frames. When applied to a stock market context, a consistent finding is that consumers prefer to buy past winners and sell past losers even when neither should be preferred. This behavior violates the normative rule of buy low and sell high.

Circulatory Response to Blood Gas Perturbations in Vasospasm

To investigate the response of the optic nerve head and the choroidal circulation to blood gas perturbations in otherwise healthy subjects with a history of cold hands. Thirty-five healthy subjects were selected and grouped according to the related history of cold hands. All 12 selected male subjects, aged 21 to 38 years (mean +/- SD = 28 +/- 5.2 years) had a negative history of cold hands. Female subjects were almost equally divided between the groups with a negative (11 subjects, aged 18-36 years; mean, 25.7 +/- 5.5) or positive (12 subjects, aged 19-45 years; mean, 25 +/- 6.8) history of cold hands. Blood gas perturbations were created by having subjects breath a gas mixture consisting of 21% O(2), 74% N(2), and 5% CO(2). The partial pressures pCO(2) and pO(2) were continuously monitored transcutaneously. Choroidal and optic nerve head blood flow response was evaluated by means of laser Doppler flowmetry. Systolic and diastolic blood pressure (SBP/DBP at baseline, three-group average: 111.2/71.9 mm Hg), heart rate (HR; 70.3 bpm), and intraocular pressure (IOP; 14.7 mm Hg) increased during the blood gas perturbation phase (123.1/77.7 mm Hg, 78.5 bpm, and 15.6 mm Hg, respectively) and returned to baseline in the recovery phase (109.9/73.4 mm Hg, 69.5 bpm, and 13.5 mm Hg, respectively). There was no difference between groups (one-way ANOVA of the percentage change from baseline for SBP, P = 0.75; DBP, P = 0.36; HR, P = 0.95; and IOP, P = 0.72). pCO(2) increased from 5.52 to 6.59 kPa and returned to 5.50 kPa. pO(2) increased from 10.64 to 13.12 kPa and returned to 10.73 kPa. Again, there was no difference between groups (one-way ANOVA for the percentage change: pCO(2), P = 0.17; pO(2), P = 0.78). In the women with vasospasm, optic nerve head blood flow increased 17.1% and the choroidal blood flow decreased -3.6%, whereas in the women and men without vasospasm the optic nerve head blood flow decreased -5.8% and -4.8%, and the choroidal blood flow increased 13.3% and 18.3%, respectively (two-way ANOVA interaction; P = 0.001). The pCO(2) increase was accompanied by a pO(2) increase. Blood pressure and HR increased comparably in all groups, indicating sympathetic arousal. The women with vasospasm demonstrated an inverse response pattern of choroidal and optic nerve head circulation to blood gas perturbation compared with the women without vasospasm and compared with the men.