Cycle In Man Research Articles

Factors influencing the outcome of in-vitro fertilization with percutaneous aspirated epididymal spermatozoa and intracytoplasmic sperm injection in azoospermic men.

In-vitro fertilization (IVF) by intracytoplasmic sperm injection (ICSI) with spermatozoa retrieved by percutaneous epididymal sperm aspiration (PESA) is a novel, simple and effective treatment for azoospermic men. In all, 38 azoospermic men had an IVF/PESA/ICSI cycle. A total of 42 cycles were performed. The aetiology of azoospermia was classified as failed vasectomy reversal (12 patients/16 cycles), inflammatory obstruction (five patients/five cycles), partial testicular failure (five patients/five cycles) and bilateral congenital absence of vas (16 patients/16 cycles). Adequate sperm preparations for ICSI were obtained from 38 of the 42 treatment cycles (90%). The mean fertilization rate was 32.7%, and fertilization occurred in 35 cycles (92.0%). Embryo transfer was performed in 13 out of 14 cycles (93%) in men with a failed vasectomy reversal, four out of five cycles in men with an inflammatory obstruction (80%), four out of four cycles in men with a partial testicular failure (100%), and 14 out of 15 cycles in men with a bilateral congenital absence of vas (93%). The overall pregnancy rate per two or three embryos transferred was 28.6 and 26.3% per treatment cycle respectively. The sperm parameters of the final pooled sperm aspirate preparations varied widely among the four aetiological groups. These parameters were of no value in predicting the fertilization or pregnancy rates (P > 0.05), and neither was the embryo cleavage rate.

Peak oxygen deficit during one- and two- legged cycling in men and women

The objectives of this study were to determine the relationships of estimated active muscle mass and gender to anaerobic capacity, as measured by the peak oxygen deficit, and to compare these relationships with those for peak oxygen uptake (VO2peak). Fat-free leg volumes (FFLV), and one- and two-legged cycling peak oxygen deficit and VO2peak were determined in young, physically active men (N = 11) and women (N = 9). For men and women, mean (+/- SD) peak oxygen deficit for one-legged cycling (2.27 +/- 0.30 and 1.18 +/- 0.18 l) was 52% of that for two-legged cycling (4.40 +/- 0.62 and 2.25 +/- 0.28 l). For all subjects and both modes of exercise, there was a strong linear relation between peak oxygen deficit (1) and estimated active muscle mass (FFLV) (r = 0.94). This relation was the same in one- and two-legged cycling, but was different for men and women. For a given FFLV, the peak oxygen deficit was significantly higher (P < 0.05) in men than women by an average of 0.44 l. The relation of peak oxygen deficit to FFLV was significantly stronger than the relation of VO2peak to FFLV (r = 0.80). We conclude: (a) that the peak oxygen deficit is strongly related to the estimated active muscle mass during cycling; (b) that for a given estimated active muscle mass (FFLV), the peak oxygen deficit is higher in men than women; and (c) that the peak oxygen deficit is more strongly related than VO2peak to the estimated quantity of active muscle.

Dimensional analysis of the sleep-waking cycle in man and monkey

Dimensional analysis of the sleep-waking cycle in man and monkey

Atrial natriuretic peptide, renin activity, aldosterone, urine volume and electrolytes during a 24‐h sleep‐wake cycle in man

To investigate the diurnal variation in the plasma atrial natriuretic peptide (ANP) concentrations and its relation to renin activity, aldosterone, urine volume and electrolytes, blood samples from six healthy male subjects were collected and blood pressure and heart rate recorded every 4 h during a 24-h sleep-wake period. Systolic blood pressure and heart rate were at the lowest during sleep. Plasma ANP, extracted on Sep-Pak cartridges and measured by radioimmunoassay, had the highest concentration at midnight and lowest at 04.00 h (27 +/- 18 vs 16 +/- 18 ng l-1, mean +/- SD, P less than 0.05 after normalization of the original values). Plasma renin activity and aldosterone were at the highest at 08.00 and 12.00 h, whereafter they both began to decrease (P less than 0.001, also normalized). Urinary volume, sodium, potassium and chloride showed highest values (P less than 0.05) between 08.00 and 16.00 h. Plasma ANP levels did not correlate with systolic blood pressure, heart rate, serum or urinary Na or plasma renin or aldosterone (r = 0.1-0.3, P greater than 0.05). Plasma renin activity correlated with aldosterone and aldosterone with urinary K (r = 0.66 and 0.58 respectively, P less than 0.001). These results suggest that the low plasma ANP levels found in our subjects at 04.00 h may be associated to diminished atrial distension accompanied by the inactivity of the sleep period. In addition, ANP does not appear to affect the secretion of renin and aldosterone in a normal sleep-wake cycle.

Cerebral glucose utilization during sleep-wake cycle in man determined by positron emission tomography and [ 18F]2-fluoro-2-deoxy- d-glucose method

Using the [ 18F]fluorodeoxyglucose method and positron emission topography, we studied cerebral glucose utilization during sleep and wakefulness in 11 young normal subjects. Each of them was studied at least thrice: during wakefulness, slow wave sleep (SWS) and rapid eye movement sleep (REMS), at 1 week intervals. Four stage 3–4 SWS and 4 REMS fulfilled the steady state conditions of the model. The control population consisted of 9 normal age-matched subjects studied twice during wakefulness at, at least, 1 week intervals. Under these conditions, the average difference between the first and the second cerebral glucose metabolic rates (CMRGlu was: −7.91 ± 15.46%, which does not differ significantly from zero ( P=0.13). During SWS, a significant decrease in CMRGlu was observed as compared to wakefulness (mean difference: −43.80 ± 14.10%, P < 0.01). All brain regions were equally affected but thalamic nuclei had significantly lower glucose utilization than the average cortex. During REMS, the CMRGlu were as high as during wakefulness (mean difference: 4.30 ± 7.40%, P=0.35). The metabolic pattern during REMS appeared more heterogenous than at wake. An activation of left temporal and occipital areas is suggested. It is hypothetized that energy requirements for maintaining membrane polarity are reduced during SWS because of a decreased rate of synaptic events. During REMS, cerebral glucose utilization is similar to that of wakefulness, presumably because of reactivated neurotransmission and increased need for ion gradients maintenance.

Electromyographic evidence of selective fatigue during the eccentric phase of stretch/shortening cycles in man

Ten male subjects were tested to determine the effects of muscle fatigue upon the activation pattern of the two main ankle extensor muscles, the 'slow-twitch' soleus (SOL) and the relatively 'fast-twitch' medial gastrocnemius (MG), during a fatiguing 60-s trial of hopping to maximal height. The myoelectric signals from SOL and MG were recorded together with the vertical ground reaction force signal and analysed by means of a computer-aided electromyograph (EMG) contour analysis, i.e. two-dimensional frequency distributions were obtained relating the activation patterns of the two synergists. The EMGs were also full-wave rectified and integrated (IEMG) according to three phases of the hopping movement (PRE, pre-activation phase; ECC, eccentric phase; CON, concentric phase). Results indicated that there were significant decreases (P less than 0.01) in the peak ground reaction force, the height of hopping and the mechanical power per unit body weight at the end of the fatiguing contractions. These decreases in mechanical parameters were accompanied by significant (P less than 0.01) decreases in all three phases of MG IEMG while SOL IEMG showed no such significant declines, except in the CON phase. Thus, the decreased mechanical parameters could in large part be accounted for by the substantial and selective decline of the excitation level of the relatively fast-twitch MG muscle. Our data suggest that the centrally mediated pre-activation of the fatiguable MG muscle as well as the MG activation during the eccentric phase, which is largely controlled by supraspinal inputs and stretch-reflex modulation, are most affected by fatigue changes during repeated maximal stretch/shortening cycles of the ankle extensors.

Hereditary disorders of the urea cycle in man: biochemical and molecular approaches.

Since H.A. Krebs, many studies have been carried out on the urea cycle, its enzymes, and their deficiencies in man. This paper has reviewed biochemical and molecular research on this subject to date. By now, all of the urea cycle enzymes other than N-acetylglutamate synthetase have been purified to homogeneity from human liver and characterized in detail. Clones of cDNA for all the enzymes have been isolated. Primary amino acid sequences of OTC, ASS, and arginase have been deduced from their cDNA nucleotide sequences. RFLPs were found in the gene loci of CPS, OTC, and ASS. These results may enable us to clarify the pathogenesis of urea cycle enzyme deficiencies at the molecular level, and may offer new therapeutic procedures, including gene therapy. Research on the organ-specific enzyme defects seen in citrullinemia, argininosuccinic aciduria, and probably argininemia may give us some insights into organ-specific gene expression in general. On the other hand, the characterization of membrane transport proteins is still in the early stages. Purification of the membrane proteins may be necessary for further research.

Uterine activity during sleep.

REM-related increases in uterine activity were found in 10 healthy young adult volunteer subjects. Contraction baseline pressures were elevated compared with NREM sleep, stage 2 sleep, stages 3 and 4 slow wave sleep (SWS), and stage 0. Contraction amplitudes during REM sleep were greater than those during SWS and stage 0, while contraction rates differed only between REM sleep and SWS. The results strongly indicated a cycle of genital activity in women that parallels the penile erection cycle in men. The implications of this finding and suggestions for future research are discussed.

Masking of the Circadian Rhythms of Heart Rate and Core Temperature by the Rest-Activity Cycle in Man

Heart rate and core temperature are elevated by physical activity and reduced during rest and/or sleep. These masking effects may confound interpretation of rhythm waveforms, particularly in situations where the rest-activity rhythm has a different period from that of the core temperature rhythm. Such desynchronization often occurs temporarily as an individual adjusts to a new work shift or to a new time zone following rapid transmeridian travel, making it difficult to assess the impact of such schedule changes on the circadian system. The present experiments were designed to estimate the magnitude of these masking effects, by monitoring the heart rate, rectal temperature, and nondominant wrist activity (2-min samples) of 12 male subjects during 6 days of normal routine outside the lab and during 6 days of strict bedrest. Subjects also kept sleep, dietary, and exercise logs throughout the study. Average (20-min) waveforms were computed for each subject and each rhythm, at home and in bedrest. In addition, data were partitioned according to self-reported sleep and wake times and were analyzed separately for each state. Average waveform comparisons indicated that about 45% of the range of the circadian heart rate rhythm during normal routine was attributable to the masking effects of activity during wake, which also produced a 16% elevation in mean heart rate during wake and an 11% increase in mean heart rate overall. (Analysis of variance indicated that mean heart rate during sleep at home was not significantly different from the mean during sleep in bedrest.) On average, about 14% of the range of the circadian temperature rhythm during normal routine was attributable to the effects of activity masking. However, the change in range of the temperature rhythm, from home to bedrest, was very variable between subjects (-41% to +13%). This variability was not accounted for by age or by reported frequency of exercise at home. Normal activity during wake increased the mean temperature during wake by an average of 0.16 degrees C and the overall mean by about 0.12 degrees C. (Analysis of variance indicated that mean temperature during sleep at home was not significantly different from the mean during sleep in bedrest.) A 10-hr "night" (lights-off from 2200 to 0800 hr) was provided during bedrest, within which subjects could select their own sleep times. Times of sleep onset and wake onset were not significantly different between home and bedrest.(ABSTRACT TRUNCATED AT 400 WORDS)

Variations in the 5-hydroxyindoleacetic acid concentration in the cerebrospinal fluid during the sleep-wake cycle in man

A variation in the ventricular fluid 5-HIAA concentration has been observed during the phases of the sleep-wake cycle in man. This variation affects the NREM phase, during which 5-HIAA increases markedly, rather than the waking state and the REM phase. The results are discussed in relation to the possible relevance of serotonin to the sleep mechanism.

Human interdigestive and postprandial gastrointestinal motor and gastrointestinal hormone patterns.

Fasting gastrointestinal motor and hormone patterns were studied in 11 healthy volunteers. Cyclic motor activity was present in all subjects during fasting, but the duration and site of onset of each cycle were variable, even in the same subject. Fasting gastrin, GIP, and glucagon levels remained low and constant during the 8-hr study, while plasma motilin levels exhibited cyclic variation in 7 of the 11 subjects. Achlorhydria (induced with cimetidine in 5 of the 11 subjects) did not alter the pattern of fasting motor activity or plasma motilin. In the remaining six subjects, the effect of liquid nutrient meals was examined. Ingestion of a sodium chloride bolus failed to disrupt fasting cyclic activity, while all nutrient-containing solutions inhibited gastric phase-2 motor activity, the duration of inhibition being longest for the mixed and lipid meals. All nutrient meals released GIP, while only protein and mixed meals released gastrin, and the lipid meal released motilin. Our study confirms the rhythmicity of interdigestive motor cycles in man and demonstrates their lack of dependence on gastric acid secretion and some relationship to motilin cycles in certain individuals as determined by radioimmunoassay. Transition from fasting to fed pattern (after liquid meals) is characterized by the inhibition of phasic gastric pressure changes in the antrum and the development of irregular activity in the intestine, similar in pattern to fasting phase 2. Because the duration of interruption of the gastric interdigestive pattern by meals depends on their nutrient content, we conclude that dietary composition may be a major determinant of the fasting-fed motor balance in man.

Amino Acid Cycles in Man

Amino Acid Cycles in Man

Carotid baroreflex heart rate control during the active and the assisted breathing cycle in man

The interaction between the phase of the breathing cycle and the carotid baroreflex heart rate control was studied in fifteen healthy subjects with special reference to respiratory sinus arrhythmia (RSA). Carotid baroreceptors were stimulated by neck suction. With a standardized breathing pattern, two types of experiment were performed. (a) Neck suction applied in counter phase with the respiratory arterial pressure variations; this reduced the amplitude and shifted the phase of the transmural carotid arterial pressure oscillations but did not influence the RSA. (B) During active as well as ventilator assisted breathing, brief periods of neck suction were applied during either inspiration (insufflation) or expiration. Neck suction during active inspiration did not change the amplitude of the RSA but when applied during expiration, increased it by 6.8 beats X min-1 (P less than 0.001). In the ventilator experiments, neck suction during insufflation and expiration augmented the RSA equally, by 5.3 beats X min-1 (P less than 0.05). The results indicate a decreased sensitivity of the carotid arterial baroreflex during active inspiration, with no equivalent during assisted breathing, and suggest that the change in baroreflex sensibility is a prerequisite for the rise of the RSA.

The reproducibility of movement parameters of the empty open—close—clench cycle in man and their dependency on the frequency of movements

The reproducibility of the empty open-close-clench cycle has been investigated. Four subjects were asked three times to perform thirty empty open-close-clench movements at each frequency of 1/2, 1 and 2 cycles s-1. To describe such a series of thirty movements a set of nine parameters were selected. By reference to these parameters it was found that the subjects were not always able to exactly reproduce a series of thirty movements at a repeat test. The movement-parameters strongly depended on the frequency of the movements. On increasing the frequency the durations of time in which a movement cycle was divided decreased, while the maximum jaw speeds during opening and closing and the jaw speed just before tooth contact increased. The parameter values chosen to describe the smoothness of the movements performed, indicated that the smoother movements were executed at the higher frequencies.

Cachexia of malignancy.Potential role of insulin in nutritional management

Patients manifesting the syndrome of cachexia of malignancy exhibit an abnormal diabetic glucose tolerance. In our patients this has been correlated with a marked resistance to administered insulin, while insulin receptors on monocytes are normal. Lipolysis remains responsive to the effects of insulin. The oxidation of FFA, as a substrate for metabolism, has been reported to be increased, and the utilization of glucose as a metabolic fuel is reduced. Increased Cori cycle activity has been demonstrated, which produces an enhanced gluconeogenesis from lactate and amino acids; there is an expenditure of 6 ATP for the synthesis of each mole of glucose. An attempt to interrupt the Cori cycle in man, using hydrazine sulfate to inhibit the enzyme phosphoenolpyruvate carboxykinase, has not resulted in reproducible clinical benefit. However, successful treatment of the underlying tumor may produce a total reversal of the cachexia syndrome, suggesting that neoplasms have the potential to elaborate an, as yet, unidentified metabolic toxin. The use of insulin to counteract the reported abnormalities should be examined as a possible supportive measure in the total nutritional management of the cancer patient.

The relationship of the renin-angiotensin-aldosterone system to plasma gonadotropin, prolactin, and ovarian steroid patterns during the menstrual cycle

Fasting supine renin activity, renin substrate concentration and aldosterone concentration in plasma were measured every other day during a complete menstrual cycle in 14 healthy young women; the patterns of LH, FSH, estradiol-17β, progesterone, 17α-hydroxyprogesterone, 4-androstendione, and prolactin in plasma were also determined radioimmunologically. During the luteal phase, the activity of the renin-angiotensin-aldosterone system is increased, probably due to the natriuretic effect of progesterone; very low progesterone values are accompanied by an early decrease of renin activity and aldosterone concentration. In some subjects, there were also peaks of renin and aldosterone in the late follicular phase or at the time of the LH surge. The mechanism of these changes is not yet clearly understood; however, it seems reasonable to assume that fluctuations of renin substrate concentration, which were demonstrated for the first time during the menstrual cycle, are related to this observation. Alternatively there may be a transient natriuresis induced by the estradiol secretion from the riping follicle. There is no temporal relationship between the periovulatory variations in 17α-hydroxyprogesterone concentration and in the renin-angiotensin-aldosterone system. Unexpectedly, plasma renin substrate concentration and renin activity were higher in the follicular phase of women with luteal failure. Neither prolactin, which was slightly higher during the luteal phase and during menstruation, nor gonadotropins seem to be directly related to the behavior of plasma renin activity or aldosterone concentration during the menstrual cycle in man.

Patterns of tooth displacement in simulated chewing cycles in man

A method described previously for recording in two dimensions the displacement path of a point on the surface of a tooth under occlusal stress was applied to the upper left canine and upper left first molar in several subjects. The results confirmed the earlier findings that the displacement path of the canine was an almost straight line, that the return path was very close to the outward path and that separation of the teeth did not occur until the test tooth had recovered half or more of its displacement. The displacement path of the molar was considerably steeper than that of the canine and was sometimes curved. In these cases, the return path was still generally straight.

The nucleolar cycle in man.

Tissue cultures of human embryonal kidney and ovary were examined. In the nuclei of both tissues, one to ten nucleoli have been found. The maximum number of nucleoli is connected with the gene expression of rDNA of the 10 nucleolus organizers of chromosome pairs Nos. 13, 14, 15, 21 and 22, which have secondary constrictions and are the satellite chromosomes in man. The small percentage of cells with 10, 9 and 8 nucleoli is attributed to the rapid association of 3 of the homologous acrocentrics (perhaps of group D). Two of the satellite (SAT) pairs probably associate later after mitosis. The process of fusion is dynamic, resulting in one interphase nucleous--a manifestation of the association of all SAT chromosomes. Dissociation of the nucleolus occurs upon entering prophase, due to the condensation of the chromosomes and retreat of rDNA to the respective secondary constrictions. As a result, the nucleolar number increases again. The pattern of the nucleolar kinetics within the course of one mitotic division is described.

Anthelmintics

This article describes the drugs used in helminthic infections and their therapeutic indications, mode of action, toxicity and other details of each of the recommended drugs, and discusses the nature and treatment of infection by helminths important in human medicine. Infestation due to the roundworms Enterobius vermicularis, Ascaris lumbricoides and the hookworms, Ancylostoma duodenale and Necator americanus can all be treated effectively with pyrantel pamoate. For Enterobius vermicularis, however, a newer drug, mebendazole, is equally as effective. The advantage of these drugs in the indicated circumstances is that they can be administered in a single dose. Unfortunately, pyrantel pamoate is not a panacea and in the case of Necator it is not as effective as in the other roundworms. In that situation the use of tetrachlorethylene is preferable. For treatment of Strongyloides stercoralis, and important human parasite, because it can become disseminated and lead to fatal infections in immunoincompetent hosts, the only effective drug is thiabendazole. In treatment of Trichuris trichiura infection, mebendazole, administered over a period of 3 days, is the most effective available drug. For the roundworms inhabiting tissues--either as aberrant infections of man or as the normal part of their life cycle in man--therapy tends to be largely non-specific. For example, in visceral larva migrans, caused by the dog roundworm Toxocara canis, only palliative therapy with systemic anti-inflammatory agents and corticosteroids may be helpful. Cutaneous larva migrans, caused by the dog hookworms Ancylostoma brasiliensis and Ancylostoma caninum, is also treated primarily with symptomatic measures, but there is a suggestion that thiabendazole may kill the larvae and thus be effective. Trichinella spiralis may cause severe, even fatal infections in man, but only symptomatic therapy can be offered. Therapy for filarial infections is regrettably complicated and not completely effective. Diethylcarbamazine remains the best available drug, but in some of these infections local surgical excision may also be used. It is important to bear in mind that release of antigens from dying or dead worms may cause systemic inflammatory and allergic reactions that may require therapy with corticosteroids. Therapy for Cestodes is achieved most effectively with niclosamide, but the antimicrobial agent paromomycin has also been effective. For the aberrant cestode infections of man, such as echinococcal cysts or Taenia solium cycticerci, treatment is surgical if the affected areas are accessible. Treatment of schistosomal infections is quite toxic and, therefore, it is mandatory to determine viability of the worms before recommending therapy. If therapy is required, then Schistosoma mansoni infections are treated with stibophen and S. japonicum with antimony potassium tartrate, taking care in both of these instances to watch for the early signs of antimony toxicity; therapy of S. haematobium infections is based on administration of niridazole...

Colonization cycles in man and beast

Abstract Pre‐industrial man and other animal species are compared with respect to colonization cycles, i.e. the cycles of population expansion and contraction that provide the historical basis for instantaneous biological distribution patterns. Because every species is basically different from every other species, biogeography has developed a common framework for understanding such unlike distributions as those of giraffes, oak trees and man by seeking relations among key variables or processes relevant to any species. Like other species, man reproduces, dies, disperses, exploits environments of varying stability and productivity, adapts phenotypically and genetically, is subject to intraspecific competition and ‐ still like other species ‐ differs from other species in particular characteristics of each of these processes. These key ingredients for biogeographic analysis are discussed to inquire in what ways man is unique as a colonist.