Unpredictable Occurrence Research Articles

Calcitonin deficiency after radioactive iodine treatment.

Brief Reports1 October 1988Calcitonin Deficiency after Radioactive Iodine TreatmentJ. J. Body, MD, N. Demeester-Mirkine, MD, J. Corvilain, MDJ. J. Body, MDSearch for more papers by this author, N. Demeester-Mirkine, MDSearch for more papers by this author, J. Corvilain, MDSearch for more papers by this authorAuthor, Article, and Disclosure Informationhttps://doi.org/10.7326/0003-4819-109-7-590 SectionsAboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinkedInRedditEmail ExcerptBecause the long-feared carcinogenic and genetic hazards of radioactive iodine (131I) have been refuted (1), many authors now consider this therapy the treatment of choice for patients with toxic multinodular goiter and for most patients with Graves disease. Moreover, the use of ablative doses was recently recommended to correct hyperthyroidism rapidly and to cause hypothyroidism predictably, contrasting with the delayed and unpredictable occurrence of hypothyroidism after conventional131I treatment (2). Intrathyroidal C cells do not trap radioactive iodine but could be damaged indirectly due to their contiguity to follicular cells, as suggested by some reports (3) of an antitumoral effect...

Identification and management of shoulder dystocia

Shoulder dystocia is most often an unpredictable occurrence. Inappropriate management may lead to long term sequelae for both mother and infant. Correct management includes specific steps to follow when attempting to deliver the infant with shoulder dystocia. It is imperative that we as nurse-midwives be thoroughly familiar with the difficulties encountered with shoulder dystocia and commit the management steps to memory. This paper presents an overview of the problem as well as the steps included in clinical management.

Patterns in helminth communities in freshwater fish in Great Britain: alternative strategies for colonization.

Examples of the apparently stochastic nature of freshwater fish helminth communities illustrating the erratic and unpredictable occurrence and distribution of many species are provided for six species of fish from several localities throughout Britain. By focussing on parasite colonization strategies two categories of helminths are recognized: autogenic species which mature in fish and allogenic species which mature in vertebrates other than fish and have a greater colonization potential and ability. Three groups of fish are distinguished: salmonids, in which helminth communities are generally dominated by autogenic species which are also responsible for most of the similarity within and between localities; cyprinids, in which they are dominated by allogenic species which are also responsible for most of the similarity within and between localities; and anguillids, whose helminth communities exhibit intermediate features with neither category consistently dominating nor providing a clear pattern of similarity. Recognition and appreciation of the different colonization strategies of autogenic and allogenic helminths in respect of host vagility and ability to cross land or sea barriers and break down habitat isolation, and their period of residence in a locality, whether transient or permanent, provides an understanding of, and explanation for, the observed patchy spatial distribution of many helminths. Comparison with other parts of the world indicates that colonization is a major determinant of helminth community structure.

The risk-benefit ratio of anticonvulsant drugs.

The concepts underlying the notion of a risk-benefit ratio for anticonvulsant therapy have determined the development of the drug treatment of epilepsy over many years. The risk element in the ratio arises from the various possible physical and psychological adverse effects of anticonvulsant therapy; the benefit is derived from the capacity of therapy to prevent seizures and thus reduce the disadvantages which result from having epilepsy. The physical adverse effects of anticonvulsant therapy may involve many tissues and organs. The drugs tend to depress cerebral, cerebellar and brain stem function, and may slow peripheral nerve conduction. Prolonged intake may cause hypocalcaemia and osteoporosis, folate depletion, various haematological and immunological abnormalities, and overgrowth of subcutaneous and gingival tissues. Idiopathic reactions may involve the skin, lymph nodes, liver, pancreas, kidney and thyroid, and cause electrolyte disturbances, while maternal anticonvulsant intake during pregnancy may be associated with an increased incidence of fetal malformations. Local reactions may occur at drug administration sites, and anticonvulsants may interact pharmacokinetically and pharmacodynamically with co-administered drugs. The taking of anticonvulsants sometimes has undesirable psychological effects on both the patient and his or her family. Epilepsy itself often results in adverse psychological consequences which emanate from the uncertainty and insecurity that is imposed by the unpredictable occurrence of seizures, from the limitations epilepsy sets on the patient's lifestyle and employment prospects, and from unfavourable community attitudes towards the disorder. Contemporary anticonvulsant therapy is not fully effective in all patients, but to the extent that it can control seizures it may help alleviate these emotional burdens that are a result of epilepsy. The consensus of present day medical opinion is that, in the great majority of clinical situations, the benefits of anticonvulsant therapy outweigh the disadvantages. However, to provide optimal management for individual patients, the risk-benefit ratio of therapy must be repeatedly assessed at all stages of a patient's treatment, and therapeutic decisions taken in the light of the ratio as it applies to the individual.

Percutaneous transluminal coronary angioplasty: state of the art and future directions.

Current developments in the practice of percutaneous transluminal coronary angioplasty concern increasing the safety of the procedure and reducing the incidence of lesion recurrence. Technical improvements and increased operator experience have greatly expanded the indications for the procedure. With experience, success in dilating proximal discrete lesions is now almost absolute. Old, calcified lesions and chronic total occlusions remain the barriers to total success. Careful case selection and expert anaesthesiology and surgical support are paramount in maintaining low complication rates. The largely unpredictable occurrence of acute vessel reclosure in approximately 2% of patients remains the major problem. This complication is usually the result of uncontrolled intimal dissection. These risks are considerably increased in patients with multivessel and diffuse disease and long lesions. Randomized trials are required to determine if such patients are best managed with bypass graft surgery. Early detection of less advanced coronary disease will ultimately lead to the most effective application of PTCA. Lesion recurrence may be reduced, in part, by careful attention to achieving an optimal, initial arteriographic and haemodynamic result. Otherwise, the solution to restenosis will depend on the development of pharmacological agents which prevent the rapid regrowth of atheromatous plaque.

The spontaneous occurrence of paroxysmal supraventricular tachycardia.

The seemingly unpredictable occurrence of paroxysmal supraventricular tachycardia has impeded understanding of its clinical course. We documented recurring tachycardia by telephone transmission of the electrocardiogram in 14 patients and measured the "tachycardia-free periods" between the start of therapy and the first recurrence of tachycardia and between successive recurrences. We showed that attacks of tachycardia were clinically independent by calculating the autocorrelation function for 12 to 14 consecutive tachycardia-free periods. We also found that the periods between attacks closely fit an exponential probability distribution, indicating that the occurrence of tachycardia in time was a type of random event called a Poisson process. Furthermore, occurrence of tachycardia was uniformly distributed throughout a dosing interval; there was no predilection for tachycardia to occur late in a dosing interval when plasma drug levels were presumed to be lowest. Measuring the tachycardia-free period is a simple and useful method for objectively studying paroxysmal supraventricular tachycardia and may be applied to the study of other paroxysmal arrhythmias.

The Psychology of Lineup Identifications1

A review is made of issues and data on eyewitness identifications, and a relative‐judgment conceptualization is proposed. It is argued that eyewitnesses are prone to choose the lineup member who most resembles the perpetrator relative to other lineup members as evidenced by studies that manipulated similarity of lineup members. The relative‐judgment strategy is fallacious because of the unpredictable occurrence of target‐absent lineups and is not corrected fully by instructions to eyewitnesses. An extension of the relative‐judgment conceptualization proposes an inverse relationship between the goodness of witnesses' memories (quality and quantity of relevant information available in memory) and witnesses' tendencies to rely on relative judgments. This extended conceptualization was used to derive expectations regarding an experiment (N= 192 eyewitnesses) that used a blank lineup prior to presenting eyewitnesses with the actual lineup. The data indicated that a blank lineup can yield a diagnostic split of eyewitnesses; those who made no identification when presented with a blank lineup were less likely to make false identifications on the actual lineup than either the witnesses who identified someone from the blank lineup or the witnesses who were not presented with a blank lineup. The blank lineup did not produce a significant loss in accurate identifications. The practical implications of using blank lineups and the theoretical utility of the relative‐judgment conceptualization are discussed.

Survival Value of An Opportunistic Life-stage Transition in Capelin (Mallotus villosus)

We examined the biological basis of the synchrony between the onset of a pelagic existence in beach-spawned capelin (Mallotus villosus) larvae and the unpredictable occurrence of favorable predator–prey conditions caused by onshore winds. Larvae isolated from the in situ beach sediments, but subject to those changes in water mass characteristics as might remain when such water is introduced into an experimental constant-level tank, emerged in synchrony with larvae in situ. This supports the hypothesis that the larval response to wind-induced water-mass exchange is an active one; it represents an adaptation maximizing feeding success and minimizing mortality due to predation. This "opportunistic" life-stage transition has direct parallels in seed dormancy and diapause in insects.

Reactions to intravenous contrast media. Part I: Severe and fatal cardiovascular reactions in a canine dehydration model.

Investigations into the nature of severe and fatal reactions to contrast media have been severely limited by their unpredictable occurrence in the clinical setting and the absence of suitable laboratory models. The authors report their experience with a canine dehydration model. Intravenous administration of 2 ml/kg of 76% sodium methylglucamine diatrizoate resulted in vomiting, shock, inappropriate slowing of the heart rate, and death. ECG findings indicated suppression of sinoatrial node automaticity, a decrease in the rate of atrioventricular conduction, and depression of myocardial contractility. These results suggest two possible mechanisms: (a) enhanced vagal tone as the result of stimulation of the vasomotor center of the medulla or (b) accentuation of direct contrast-induced myocardial toxicity.

Towards safer colonoscopy: a report on the complications of 5000 diagnostic or therapeutic colonoscopies.

The diagnostic and therapeutic benefits of colonoscopy are well known but most large-scale surveys, especially those involving multiple centres, may underestimate the range and incidence of complications. The detailed records of 5000 colonoscopies in a specialist unit have been analysed and conclusions drawn which may help to make the procedure safer. The incidence of haemorrhage was 1% and bowel perforation 0.1%. All the major haemorrhages occurred during polypectomies over 2 cm in size. Secondary haemorrhage was an unpredictable occurrence, one to 14 days later. Three deaths followed colonoscopy: one cardiorespiratory death was related to oversedation; a second was due to mismanaged ischaemic colitis developing two days after traumatic instrumentation, and the third was due to peritonitis. Minor complications included thrombophlebitis, abdominal distension, and vasovagal episodes. Because of experience during the first half of the series and also due to improvements in instrumentation, the complication rate of the later part of the series was halved. Recommendations include the avoidance of oversedation, review of previous barium enema films so as to be aware of large polyps which are more likely to bleed, and the recognition of situations where perforation or septicaemia is likely to occur.

Rh-D factor in trophoblastic tumors: A possible cause of the high incidence in Asia

thickening previously referred to as unsoftened segments in 71% of 881 pregnancies between 14 and 30 weeks’ gestation. They observed a significant change in the configuration of these segments within a 30-minute period and concluded that uterine contractions were the cause. Because the majority of amniocenteses considered difficult (more than one attempt necessary or fluid initially blood tinged) occurred in patients with a prominent uterine contraction, these authors modified their procedure by waiting for an observed contraction to relax before selecting a needle path. This case report is presented as a representative example of a phenomenon seen repeatedly in our laboratory and to indicate an approach to dealing with this problem. If the initial aspiration returns either blood or no fluid, the ultrasound sector scanner is used to assess the situation before the needle is advanced or withdrawn, the trajectory is changed, or a second amniocentesis site is selected. The unpredictable occurrence of a myometrical contraction in response to an inserted needle with a consequent shift of amniotic fluid spaces is a strong reason for performing amniocentesis in the ultrasound suite and in particular with real-time monitoring equipment available.

The pharmacokinetics of metoclopramide in man with observations in the dog.

1 The pharmacokinetics of metoclopramide have been studied in eight normal male volunteers. 2 The mean plasma beta half-life was 156.7 min after i.v. administration of 10 mg metoclopramide. 3 After oral dosing of 10 mg the mean half-life was 196.6 min and after 20 mg 317.5 min (P less than 0.05). 4 Bioavailability of a 10 mg oral dose of metoclopramide varied between 32 and 97%. 5 A major urinary metabolite was metoclopramide-N-4-sulphate and the amounts of conjugates appearing in urine to 24 h correlated significantly with the bioavailability. 6 In the dog the metabolic fate of metoclopramide is different to man with conjugation being a minor metabolic pathway. The half-life in the dog does not appear to be dose dependent. 7 The wide differences in bioavailability of metoclopramide in man may contribute to the unpredictable occurrence of side effects.

Observations on thecate swarmers of Pyrocystis species in laboratory culture: Pyrocystis fusiformis Wyville Thomson ex Murray and Pyrocystis pseudonoctiluca Wyville Thomson ex Murray (Dinococcales)

Abstract Thecate swarmers of Pyrocystis fusiformis and P. pseudonoctiluca have been observed in laboratory cultures. At the time when inspections were made, during daylight hours, thecal development appeared to have been essentially complete. Release from the enclosing wall of the parent cell occurred in the early evening. The free-swimming phase was of short duration and was succeeded by ecdysis and rapid development of the extruded protoplast into the bladder-like vegetative form. A complete tabulation is presented here for P. fusiformis. Details of the thecal structure of this organism serve to clarify discrepancies in the literature concerning the armoured stages of both species. While the presence of thecate states remains a rare and, at present, unpredictable occurrence in the cultures of P. fusiformis and P. pseudonoctiluca maintained in this laboratory, their role in asexual reproduction appears to be similar to that of the more commonly observed athecate aplanospores.

Selection for Seedling Cold Tolerance in Safflower with Modified Controlled Environment Chambers1

The unpredictable occurrence of cold stress in the southwestern U. S. makes selection in the field for seedling cold tolerance in safflower (Carthamus sp.) a sporadic effort. Use of a conventional cold chamber has not been practical for us because temperatures within it differed by as much as 3 C among positions only 30 cm apart, and they changed among subsequent tests. Installation of a turntable made it possible to subject seedlings growing in pots placed within the same radius (circle) to a similar cold stress. We were then able to differentiate known genotypes for degree of seedling cold tolerance with as few as 10 plants of each. This degree of precision, along with controlled hardening temperatures for as little as 1 week before the cold stress, gave considerable flexibility in selection for seedling cold tolerance. In a fourway cross in which one parent was a cold tolerant selection out of the wild species, Carthamus flavescens Spreng, it was possible to program a cold stress (_16 C for hours) in which none of the most cold tolerant domestic parent, about 50% of the wild parent, and 0.5% of the seedlings in the segregating population survived. With controlled hardening temperatures and programmed cold stresses, time involved in breeding and genetic studies of seedling cold tolerance in safflower need be limited only to the time required for growing the filial generations.

An event-recording system for monitoring small earthquakes

abstract To monitor small earthquakes on the ocean bottom or in remote areas on land, a seismic recording system should operate at low power for extended periods of time, should reproduce three components of ground motion with a large dynamic range, and should preferably be small and inexpensive. We describe such a system based on an event detector, which continuously surveys the background noise, sets a threshold, and triggers an inexpensive digital tape recorder when a seismic signal exceeds that threshold. Event recording offers the advantages over conventional continuous recording of more efficient use of storage capacity and easier later interpretation. A key element of the system is a continuously updated semiconductor buffer memory, which assures that first arrivals are included. Average power consumption is about a watt. The system design is easily adaptable to monitoring other types of rare events of unpredictable occurrence.

The homologous blood syndrome: IV. Effects of autologous and homologous plasma, saline and heartworm-free homologous blood

1. 1. The homologous blood syndrome occurs in the absence of heartworms, having been demonstrated in 11 of 15 dogs undergoing constant volume exchange of homologous blood (100 ml./kg.) devoid of D. immitis microfilariae and adult worms. 2. 2. Neither buffering nor high carbon dioxide tension prevented the development of severe hypotension and metabolic acidosis during exchange of saline (100 ml./kg.) in ten experiments. 3. 3. Constant volume exchange (100 ml./kg.) of stored dialyzed autologous plasma caused no severe hypotension, acidosis, nor demonstrable allergic reactions. Homologous plasma resulted in an unpredictable occurrence of severe hypotension and intense urticaria during the exchange infusions. 4. 4. The data suggest that continuing studies with autologous plasma may provide insight into the development of a better perfusate for extracorporeal circulation. The significance of the hypotensive and allergic reactions with homologous plasma requires further investigation.

The Influence of Daylength on Reproductive Timing in the Red Crossbill

Early studies of reproductive timing in birds led to generalizations overemphasizing the importance of daylength as a regulating factor. Daylength is certainly important in stimulating gonadal development in many insectivorous passerines of temperate latitudes, but other factors, such as rainfall or its consequences, appear to control time of breeding in some birds of desert and tropical regions (Keast and Marshall, 1954; Miller, 1959, 1961; Immelmann, 1963; Oksche et al., 1963). Moreover, the unpredictable occurrence of reproduction in the Red Crossbill (Loxia curvirostra) suggests the influence of nonphotoperiodic factors on this largely boreal species. The Red Crossbill probably has the most erratic breeding schedule of any North American bird. At various localities in its range, it has been found over a period of time breeding in every month of the year. The nomadic tendencies of this species make the situation even more unusual. A locality inhabited by breeding birds in one year may not be used for several years thereafter. These irregularities in timing and location of breeding suggest that reproduction in this species is not primarily dependent on daylength. The extent of this dependence is analyzed in this paper.

Central and peripheral factors in epileptic discharge. Clinical studies.

All electroencephalographers are familiar with the apparently spontaneous and unpredictable occurrence of epileptiform activity during recording of the routine electroencephalogram (EEG). In addition, all are well acquainted with certain maneuvers which increase the likelihood that such activity will appear: e.g., eye closure, hyperventilation, darkness, quiet, light sleep. Means for arresting subconvulsive spike or spike-wave (S-W) discharges are also readily demonstrable in many patients: e.g., eye opening, loud sounds, tactile stimuli, and concentrated attention, to name but a few. In a much smaller number of subjects, specific stimuli more or less regularly elicit abnormal discharge, among them: flickered light, 10,24 music, 7 clicks and tones, 3,20 reading, 4 tactile stimuli, 1,9 and emotional and psychological stimuli. 12,21 In the course of our attempts to condition epileptiform discharges of patients with light-sensitive epilepsy to follow a neutral stimulus, 22 the relationship of a variety of peripheral stimuli to the occurrence of paroxysmal

Adrenal medullary secretion of epinephrine and norepinephrine in dogs subjected to hemorrhagic hypotension.

The response of the adrenal medulla in anesthetized dogs to hemorrhagic hypotension of a varied level and duration was observed to be primarily accompanied by a highly significant increase in adrenal plasma epinephrine. On the other hand, the secretion of norepinephrine had an unpredictable occurrence in adrenal blood samples collected in periods of hypotension. The essential determinant of adrenal blood flow was observed to be the level of mean blood pressure. While this relationship was not in strict proportion, changes in mean blood pressure were invariably followed by changes in adrenal blood flow in the same direction. The adrenal medulla of dogs in hemorrhagic irreversible shock was observed to continue to secrete epinephrine at very low levels of mean blood pressure, characteristic of terminal shock. Reports by other groups of investigators on elevated peripheral blood levels of epinephrine in hemorrhagic shock have been found to result mainly from an actively secreting adrenal medulla.

External Electric Stimulation of the Heart in Cardiac Arrest

Stokes-Adams disease consists of attacks of cerebral ischemia in patients with atrioventricular heart block. The attacks are due to inadequate circulation resulting from very slow idioventricular rhythm, ventricular standstill, ventricular tachycardia, or ventricular fibrillation. 1 Their manifestations include dizziness, syncope, prolonged unconsciousness, and convulsions, and they may end in death. At times the attacks may be frequent and severe. If the patient can survive such periods, however, he may live for many years without further episodes. 2 Stokes-Adams attacks often require emergency resuscitation, and desperate measures may be necessary. Therapy is complicated by the unpredictable occurrence, frequency, and duration of the seizures. Drugs and cardiac puncture, the only therapy heretofore available, are dangerous and often ineffective. We have developed a new therapeutic approach to this serious disease: an externally-applied cardiac pacemaker which stimulates the heart electrically, terminates ventricular standstill, and maintains an externally-paced ventricular rhythm for long periods. This approach