Transanal endoscopic microsurgery technique: an acceptable approach for retrorectal tumors.

INTRODUCTION: Retrorectal lesions (RRLs) are rare lesions that originate from the tissue present in the retrorectal space. The gold standard of care is complete resection regardless of pathology. The traditional approaches (anterior, posterior, and combined) are relatively well described. Transanal Endoscopic Microsurgery (TEM) is a minimally invasive technique offered as an alternative approach for RRLs. AIM: To evaluate the outcomes of patients diagnosed with RRL and treated by the TEM approach, especially postoperative complications, and the recurrence rate. METHODS: Patients with RRLs treated with the TEM technique in one medical center between 2000 and 2020 were identified. Their postoperative outcomes were compared with historical controls. RESULTS: Thirty-nine patients diagnosed with RRL were operated on using the TEM platform. Thirty-seven RRLs were benign, and two were malignant. Their median size (IQR) was 20 mm (15, 32.5). The median distance (IQR) from the anal verge was 50 mm (50, 72.5). The median operative time (IQR) was 48.5 min (41.75, 60). All, except one lesion, were completely resected. The median length of stay (IQR) was one day (1, 1 day). Postoperative complications were diagnosed in three patients, two of which resolved following a second operation. CONCLUSIONS: The implementation of TEM for the resection of RRLs demonstrated excellent overall results with acceptable complication and recurrence rate and represented a viable alternative surgical approach.

Identification of the sex-determining region in flathead grey mullet (Mugil cephalus).

Elucidation of the sex-determination mechanism in flathead grey mullet (Mugil cephalus) is required to exploit its economic potential by production of genetically determined monosex populations and application of hormonal treatment to parents rather than to the marketed progeny. Our objective was to construct a first-generation linkage map of the M. cephalus in order to identify the sex-determining region and sex-determination system. Deep-sequencing data of a single male was assembled and aligned to the genome of Nile tilapia (Oreochromis niloticus). A total 245 M. cephalus microsatellite markers were designed, spanning the syntenic tilapia genome assembly at intervals of 10 Mb. In the mapping family of full-sib progeny, 156 segregating markers were used to construct a first-generation linkage map of 24 linkage groups (LGs), corresponding to the number of chromosomes. The linkage map spanned approximately 1200 cM with an average inter-marker distance of 10.6 cM. Markers segregating on LG9 in two independent mapping families showed nearly complete concordance with gender (R2  = 0.95). The sex determining locus was fine mapped within an interval of 8.6 cM on LG9. The sex of offspring was determined only by the alleles transmitted from the father, thus indicating an XY sex-determination system.

Effect of teleradiology upon pattern of transfer of head injured patients from a rural general hospital to a neurosurgical referral centre: follow-up study.

INTRODUCTION: The optimal management strategy for patients with head injury admitted to a non-specialist hospital is uncertain. The aim of this study was to evaluate the outcomes of victims of head injury requiring hospitalisation but initially admitted to a rural level II trauma centre without a neurosurgical facility but with a system for neurosurgical consultation via teleradiology. METHODS: Patients admitted for head injury during 2006-2011 were included. Late transfer of patients initially hospitalised in the level II trauma centre was evaluated for treatment failure, defined as clinical or radiological deterioration. RESULTS: Five hundred and sixty-two patients were initially hospitalised in the level II trauma centre. Evaluation of late transfers showed that only 23 (4.1%) represented real treatment failures due to clinical or radiological deterioration. The clinical course was altered by primary intent to hospitalise patients in the level II trauma centre in only one patient. CONCLUSIONS: Selected patients with head trauma who have a pathological CT scan may be safely managed in level II trauma centres following neurosurgical consultation using teleradiology. Review of treatment failures is necessary to ensure proper ongoing management of a system in which neurosurgical patients are selectively transferred to trauma centres with neurosurgical capacity.

In vitro effect of cortisol and urotensin I on arginine vasotocin and isotocin secretion from pituitary cells of gilthead sea bream Sparus aurata.

This study aimed at determining whether in vitro secretion of two neuropeptides, arginine vasotocin (AVT) and isotocin (IT), from pituitary cells of gilthead sea bream Sparus aurata was affected by cortisol and urotensin (UI). Pituitary cells were exposed to 1·4 × 10(-8) , 1·4 × 10(-7) and 0·4 × 10(-6) M cortisol and 10(-12) , 10(-10) and 10(-8) M UI for 6, 24 and 48 h, respectively. AVT and IT contents were determined in the culture media by high-performance liquid chromatography (HPLC). An increase in AVT secretion and a decrease in IT secretion were observed at all cortisol doses. UI increased AVT secretion after 6 h of incubation at all doses. After 24 h, however, only the highest dose of UI still displayed an effect. IT secretion was not influenced by UI. It was thus demonstrated that cortisol does influence AVT and IT secretion from S. aurata pituitary cells, while UI regulates AVT secretion, as a component of hypothalamic-pituitary-interrenal (HPI) axis in this species.

GnRHa-mediated stimulation of the reproductive endocrine axis in captive Atlantic bluefin tuna, Thunnus thynnus.

A controlled-release implant loaded with GnRH agonist (GnRHa) was used to induce spawning in Atlantic bluefin tuna (Thunnus thynnus) during two consecutive reproductive seasons. The fish were implanted underwater and sampled between days 2 and 8 after treatment. At the time of GnRHa treatment, females were in full vitellogenesis and males in spermiation. There was a rapid burst of pituitary luteinizing hormone (LH) release at day 2 after treatment in GnRHa-treated fish, and circulating LH remained elevated up to day 8 after treatment. In contrast, control fish had significantly lower levels in the plasma, but higher LH content in the pituitary, as observed in many other cultured fishes that fail to undergo oocyte maturation, ovulation and spawning unless induced by an exogenous GnRHa. Plasma testosterone (T) and 17ß-estradiol (E(2)) were elevated in response to the GnRHa treatment in females, while 11-ketotestosterone (11-KT) but not T was elevated in males. Even though oocyte maturation and ovulation did occur in GnRHa-induced fish, no significant elevations in 17,20ß-dihydroxy-4-pregnen-3-one (17,20ß-P) or 17,20ß,21-trihydroxy-4-pregnen-3-one (20ß-S), in either the free, conjugated or 5ß-reduced,3α-hydroxylated forms was observed in fish sampled within 6 days after treatment. Interestingly, a significant peak in plasma free 17,20ß-P levels occurred in both males and females at day 8 after treatment. Histological sections of the ovaries in these females contained oocytes at the migrating germinal vesicle stage, suggesting the role of this hormone as a maturation-inducing steroid in Atlantic bluefin tuna. In conclusion, the GnRHa implants activated effectively the reproductive endocrine axis in captive Atlantic bluefin tuna broodstocks, through stimulation of sustained elevations in plasma LH, which in turn evoked the synthesis and secretion of the relevant sex steroids leading to gamete maturation and release.

Value of EUS-FNA cytological preparations compared with cell block sections in the diagnosis of pancreatic solid tumours.

OBJECTIVE: Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) is performed in order to achieve a definite tissue diagnosis of pancreatic lesions. This in turn is a guide to the appropriate treatment for the patient. Tissue samples collected by the same needle for cytological preparations and cell block histological sections (often referred to as FNA-cytology and FNA-biopsy, respectively) are handled differently. The specific contribution of each of these tests was evaluated. METHODS: One hundred and two consecutive patients underwent EUS-FNA while being investigated for pancreatic solid lesions. Diagnosis was made by cytology, cell block sections or both. The diagnosis was confirmed by clinical outcome. RESULTS: Male/female ratio was 61/41. Mean age was 65±12 years (range, 22-94). Mean lesion size was 3.1±1.8 cm (range, 0.6-10 cm); 68% were >2 cm and 75% were located in the pancreatic head. The average number of needle passes was two (range, 1-4 passes). Final tissue diagnosis was malignant in 66 (65%) patients. Sensitivity, specificity and accuracy were 73%, 94% and 81%, respectively, for cytology alone, and 63%, 100% and 78%, for cell blocks alone. Eighty-two patients (80%) had cytology and cell blocks, which matched in 64 (78%) patients. EUS-FNA results that relied on both techniques had 84% sensitivity, 94% specificity and 88% accuracy. Cytology revealed 13 malignancies not diagnosed on cell blocks, while cell blocks revealed five malignancies not diagnosed by cytology. Malignant lesions were more common in men; they were larger in size and located in the pancreatic head. CONCLUSION: EUS-FNA cytology was more sensitive than cell blocks but less specific for the diagnosis of solid pancreatic lesions. The two methods are complementary and implementing both improves the diagnostic value of EUS-FNA.

Should the management approach to the anterior abdominal stab wound be different in patients with self-inflicted abdominal injury?

BACKGROUND: Self-inflicted injury is a leading cause of death worldwide. It is hypothesized that due to instincts for self-preservation, the severity of abdominal injury would be decreased following suicidal self-stabbing in comparison to stab wounds from assault, and therefore a more conservative management might be considered. METHODS: All patients with isolated abdominal stab wound (SW) admitted to 19 Trauma Centers in Israel between the years 1997 and 2018 were included in the study. Patients with self-inflicted abdominal SW (Group I) were compared to victims with abdominal SW following assault (Group II). RESULTS: Group I included 9.4% (314/3324) of patients eligible for this study. Compared to Group II, Group I patients were older (median: 39 years, IQR 28,52 vs. 24 years, IQR 19,33; p<0.001), had more females (28.7% vs 4.9%, p <0.001), had longer length of hospitalization (median: 3 days vs. 2 days; p<0.001), underwent surgery more frequently (55.4% vs. 37.4%; p<0.001), and had higher mortality (2.9% vs. 0.7%; p=0.003). Possible covariates for mortality were examined and following logistic regression, self-inflicted injury remained associated with higher death rates compared to assault (OR 4.027, CI95% 1.380, 11.749; p=0.011). CONCLUSION: In this study, patients with isolated self-inflicted abdominal injuries had higher mortality and more frequently underwent abdominal surgery.

Early postoperative dressing removal in hand surgery: Novel concepts for individualized surgical dressing management.

Postoperative dressing protocols after clean surgery without implant vary widely. The purpose of this study was to elucidate whether early postoperative dressing removal is a valid option, as compared to untouched dressing or twice-weekly dressing change approach. A prospective randomized study was conducted on patients who underwent carpal tunnel release (CTR) or trigger finger release (TFR) between January and November 2020. Patients were randomly distributed into 3 groups: surgical dressing untouched until first follow up (SDU); surgical dressing changed twice a week in a health maintenance organization (HMO); and surgical dressing removed at first postoperative day (SDR). Data collected included patient characteristics, pre-and post-operative functional (QuickDASH) and autonomy (Instrumental Activities of Daily Living performance (IADL)) scores, Vancouver scar scale (VSS) and potential complications. Eighty-four patients were included: 28 (33.3%), 29 (34.5%) and 27 (32.1%) in the SDU, HMO and SDR groups, respectively. Deterioration in mean IADL score at 2-week follow-up was statistically significant in the HMO group (mean delta 3.35, p = 0.008). Quick DASH score improved significantly between preoperative and 2-week follow-up values only in the SDU group (mean delta 9.12, p = 0.012). Other parameters, including wound complications, did not differ significantly between groups. Early removal of postoperative dressing and immediate wound exposure was a safe option after CTR and TFR. An untouched bulky dressing correlated with early functional improvement. Finally, iterative dressing change in HMO showed no benefit and led to significant deterioration in early postoperative autonomy. IRB APPROVAL: 0548-18-TLV. LEVEL OF EVIDENCE: I.

Tympanic membrane perforation impact on severity of injury and resource use in victims of explosion.

PURPOSE: Though tympanic membrane perforation (TMP) is a marker of barotrauma, relation to severity of injury has been contested based on previous observations that following an explosion many victims with significant injuries do not suffer from TMP while many victims with TMP do not suffer from significant injuries. The objective of this study was to reassess the relationship of TMP to severity of injury and resource demand in patients treated in multiple casualty incidents following terrorist bombings treated in one medical center. METHODS: Retrospective review. RESULTS: Most of the patients with TMP were mildly injured. Nevertheless, TMP was more prevalent in patients with moderate and severe injuries, 53.3 % compared to 13.6 % in mildly injured patients (p = 0.0009). Patients with TMP suffered from more body areas injured (p < 0.0001). They more often needed surgery (30.6 vs. 5.5 %; p < 0.0001), ICU hospitalization (16.1 vs. 1.3 %; p < 0.0001) and secondary transfer to a level I trauma center (12.9 vs. 1.0 %; p < 0.0001). They were hospitalized longer (p < 0.0001). Fifty-three (12.6 %) patients included in this study were not examined by the ENT service. Most of those not examined were either moderately or severely injured. CONCLUSIONS: Patients with TMP were more severely injured and more often needed surgery, ICU hospitalization and need for transfer to a level I trauma center. The observation that all those who died in hospital and most of those who were unstable were not examined by the ENT services suggests that impact of TMP as an indicator of severity may be underestimated.

Prolactin rhythms-oscillators' response to photoperiodic cues is age and circadian time dependent.

In vivo prolactin release patterns exhibit a compound rhythm with circadian (24 h), semicircadian (12 h) and ultradian (6-8 h) periods. Changes in these rhythmic patterns were observed at different photoperiodic conditions, and in elderly. Since in vitro prolactin release was related to the photoperiodic history of the animal, we studied the effect of varying photoperioda upon the in vitro rhythmic output of prolactin release from young and old male rat pituitaries, isolated at different circadian times from animals housed at LD 12:12, 18:6 for 10 days or 6 weeks. The results indicate that, both, mean levels and rhythmic prolactin release in vitro are determined by the age of the animal, the circadian time of pituitary isolation, the photoperiodic conditions in which the animal was housed, and the duration of housing in the long day conditions. The change of the rhythmic output pattern is gradual, reflecting a process by which the oscillators respond to the external cues to fit prolactin release pattern to the environmental conditions. Each of the oscillators (e.g. circadian, semicircadian, ultradian) shows different sensitivity to the changing photoperiodic signal and is regulated at the level of phase and amplitude but not the period. In old rats the response of the oscillators to the change in photoperioda is attenuated and not sufficient to induce a change in the output of prolactin release suggesting a loss in adaptation ability.

Time dependent protection of amifostine from renal and hematopoietic cisplatin induced toxicity.

Efficacy of chemotherapy may be maximized and its toxicity can be minimized if drugs would be administered at specified daily times. The present study was aimed to examine if the protection of amifostine against cisplatin toxicity is time dependent. Amifostine is an organic thiophosphate that protects selectively normal tissues, but not tumors, against the cytotoxicity of DNA binding chemotherapeutic agents such as cisplatin. ICR male mice which were entrained to Light:Dark (L:D) 14:10 were injected (intrapritoneal bolus) for 5 consecutive days with either: cisplatin, cisplatin plus amifostine (administered 30 minutes prior to cisplatin). Injections were given at either 08:00, 13:00, 20:00 or 01:00. Five days later, on day 10, each set of mice was sacrificed (at the same hour corresponds to the injection hour), blood count, blood creatinine and blood urea nitrogen (BUN) were assayed. Cisplatin treated mice exhibited nephrotoxicity, as indicated by increased blood urea nitrogen values and by high blood urea nitrogen to creatinine ratios, as well as myelotoxicity that was indicated by low levels of hemoglobin and platelets. Co-administration of amifostine-cisplatin reversed both, the nephrotoxicity of cisplatin, and its myelosuppressive effects. For BUN, hemoglobin and platelets, maximal protections were observed at 08:00, (p <0.05, p <0.01 and p <0.01 respectively). For BUN/Cr ratio (p <0.05), maximal protections was observed at 13:00. These findings show that amifostine exhibits time dependent protection against cisplatin toxicity and thus it is recommended to use the protector when treatments are given during morning hours. The results also further validate the notion that chronochemotherapy is advantageous at least in reducing drug toxicity and thus should be integrated in the design of clinical protocols.

Time-dependent variations of the skin barrier function in humans: transepidermal water loss, stratum corneum hydration, skin surface pH, and skin temperature.

Although circadian rhythms have been described for many human functions, there are minimal data on circadian rhythms related to skin physiology. This study investigated the circadian rhythmicity of skin variables related to skin barrier function in humans. We measured transepidermal water loss, stratum corneum moisture, skin surface pH, and skin temperature in 16 healthy volunteers (nine men and seven women, aged 23-53 y). Subjects were sampled every 2 h in two sessions over a 24 h span. Twelve samples were obtained for each variable in the following sites: forehead, forearm, upper back, and shin. We used cosinor analysis and ANOVA to validate observed differences. Time-dependent rhythms were detected in most skin variables except in stratum corneum hydration. We found a statistically significant circadian rhythmicity characterized by cosinor analysis in transepidermal water loss, skin surface pH, and skin temperature on the forearm, forehead, and shin. Peak-trough differences occurred in all locations. The values of the same variables measured at different sites correlated positively, whereas the values of the different variables did not. These results suggest that skin permeability is higher in the evening and night than in the morning. These data may be clinically relevant in several aspects applied to skin physiology and topical drug application.

Diurnal rhythm of prostanoid secretion from bone/marrow organ in the rat.

The secretion of prostanoids from an adult diaphysial rat bone organ was assessed throughout a 24 h period at 4 h intervals as well as the 24 h activities of bone alkaline phosphatase isoenzyme and serum corticosterone levels. Femurs were removed from 16 rats at each interval and incubated in the absence or presence of indomethacin (100 micrograms). The levels of prostaglandin E2 (PGE2) prostaglandin F2 alpha (PGF2 alpha), and the stable metabolites of thromboxane and prostacyclin, thromboxane B2 (TxB2), and 6-keto prostaglandin F1 alpha (6-keto PGF1 alpha) were measured by radioimmunoassay (RIA). The patterns for each of the variables was subjected to cosinor analysis for predetermined various periods. The chronograms obtained indicated that PGF2 alpha, PGE2, and TxB2 showed 24 h rhythms with computed peak hour acrophases at 1700, 1800, and 2200 h, respectively, and prostacyclin demonstrated a 19 h rhythm with a peak secretion at 1100 h. Corticosterone levels and bone alkaline phosphatase isoenzyme activity in the serum were at peak at 1630 and 2200 h, and at nadir at 0500 and 1000 h, respectively, both exhibiting 24 h rhythms similar to those of PGF2 alpha, PGE2, and TxB2. Bone alkaline phosphatase isoenzyme activity in the femurs' incubation media showed a 12 h diurnal rhythm with peaks at 1230 and 2330 h and nadirs at 0600 and 2330 h (p < 0.01). In summary, this study demonstrated for the first time a 24 h rhythm of prostanoid secretion from diaphysial bone.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of continuous strenuous exercise on intraocular pressure.

The effect of a continuous 110-km march with a 20-kg backpack load on intraocular pressure (IOP), plasma osmolarity, blood lactate, pH, and other related laboratory parameters was studied in 22 healthy young volunteers. Intraocular pressure decreased significantly at all marching intervals and returned to baseline level 3 hr after the completion of marching. The maximal average reduction during marching was 4.1 mmHg, 26.5% below the baseline level. The IOP decreased again 48 hr after the march and returned to baseline level 48 hr later. There were two peaks of increased plasma osmolarity (one during the march and the other 48 hr after the march). There was no correlation between IOP changes and levels of pH, blood lactate, serum proteins, and electrolytes or hematologic parameters. These findings suggest that IOP reduction is related inversely to plasma osmolarity during and after strenuous exercise.

Gonadotropin releasing hormone (GnRH) and estradiol (E(2)) regulation of cell cycle in gonadotrophs.

The number of pituitary cells, their size, hormonal content and release and response to external cues varies between day and night and during the estrus cycle. Previous studies have demonstrated that pituitary cells proliferate rhythmically and that estradiol (E(2)) is a mitogen of alpha T3 cells. We, therefore, studied the effect of gonadotropin releasing hormone (GnRH) and E(2), on the cell cycle in primary cultures of mouse pituitary cells and in the gonadotroph cell line L beta T2. We found that GnRH and E(2) modulate the cell cycle in a time dependent manner and induce proliferation in cultures of mouse pituitary and L beta T2 cells. GnRH induces proliferation in cells isolated in the morning of the estrus day and increases the number of cells in G2 stage when isolated in noon and evening. However, the transition into the G1 stage is enabled only by co-addition of E(2) and GnRH. GnRH stimulates LH release from L beta T2 cells after 2 days via exocytosis while after 4 days in culture, the increase in LH release may be accounted for by the increase in cell number. E(2) enhanced the GnRH response after 2 days, and abolished it after 4 days in culture. Furthermore, E(2) has no effect on LH release and cell number after 2 days in culture, however, after 4 days in culture, E(2) had no effect on the total amount of LH released but inhibited LH release per cell due to increase in cell number. Our results show that GnRH and E(2) function to shorten the cell cycle and regulate the cell number of each stage of the cell cycle. The effect of GnRH and E(2) on the cell cycle is dependent on the circadian time. This mechanism may serve to modulate the size and function of the pituitary cell population and consequently the function of pituitary gonadotrophs regulating the surge of LH release before ovulation.

Rhythmicity of luteinizing hormone secretion expressed in vitro.

In the present study we explored the possibility that the pituitary functions as an autonomous clock and is capable of generating rhythms of luteinizing hormone (LH) release independently of hypothalamic control. Pituitaries from estrous or diestrous day 1 female mice were perifused separately with Medium-199. Effluent samples were collected at 10-min intervals and assayed for LH levels. Fourier analysis and curve-fit analysis served to elucidate the presence of prominent periods whose significance was then determined by best-fit cosinor. The latter method was used to determine additional parameters for the significant rhythm. All perifused pituitaries exhibited LH release patterns that were composed of significantly long ultradian rhythms (approximately 16 and 8 h, p < 0.001). Continuous stimulation with gonadotropin-releasing hormone (GnRH) or estradiol did not alter the periods of the observed rhythms but affected other rhythm parameters. Gonadotropin-releasing hormone increased the mesor of the rhythm and estradiol increased the amplitude. The results indicate that pituitary gonadotropes are capable of producing rhythms of LH release for a long duration in vitro, in the absence of hypothalamic control. Both GnRH and estradiol affect different rhythm parameters but do not change the periods of these rhythms.

Helicobacter pylori infection and subsequent peptic duodenal disease among young adults.

BACKGROUND: Evidence for a causal relationship between presence of Helicobacter pylori (H. pylori) in gastric mucosa and development of peptic disease is based largely on intervention studies in which eradication of H. pylori led to healing of the lesion. The aim of this study was to assess the importance of H. pylori seropositivity for subsequent development of peptic disease in a prospective study design in young Israelis. METHODS: A nested case-control serum bank study based on a systematic sample of male and female inductees to the Israel Defense Force. Twenty-nine cases of duodenal ulcer or duodenitis of moderate or higher severity, diagnosed between 1986 and 1995, were individually matched for age, sex, ethnicity, education and year of induction, with five healthy controls each. Presence of anti-H. pylori antibodies in the frozen stored sera was determined by ELISA. RESULTS: The geometric mean titre of anti-H. pylori antibodies at baseline was significantly higher in cases (18. 3 U/ml) than controls (6.9 U/ml; P = 0.009). The matched odds ratio for peptic ulcer disease by seropositivity was 3.8 (95% CI : 1.4-10. 2). A stronger association was evident for subjects diagnosed > or =2 years after induction than those diagnosed earlier. The population attributable fraction was 56.6% (95% CI : 15.7-81.1). CONCLUSIONS: Pre-existing infection with H. pylori, as determined by seropositivity, is an important determinant of development of duodenal ulcer or duodenitis in young Israelis, supporting the generalizability of an apparent causal association to diverse populations.

Differences between left- and right-hand reaction time rhythms: indications of shifts in strategies of human brain activity.

Reaction time (RT) measurements serve as quantitative indices for pilots' cognitive processes of the brain. To examine if laterality exists in the brain hemispheres we measured, by the use of a Pilot Evaluation System (PES), right- and left-hand performance rhythms as indicative of RT to audible and visual stimuli. The tests included sets of simple tasks and complex ones to which a secondary task composed of audio signals was added. The accuracy of recorded reaction time was 27 ms. Seven right-handed males, 27-42 years of age, experienced with the PES flight simulator, were tested every 2 h, nine times daily (starting at 08:00 h) during 3 consecutive days. The results indicated that for simple tasks, the 24 h period of RT rhythm is either exclusive or prominent for both hands. For complex tasks the prominent period of RT is 24 h for the right (dominant) hand and 8 h for the left (non-dominant) hand (right-hand 24 h period Fstat = 140, r2 = 0.62 and 8 h period Fstat = 25, r2 = 0.22; left-hand 24 h period Fstat = 44, r2 = 0.34 and 8 h period Fstat = 100, r2 = 0.54). The findings suggest that a laterality exists in the brain hemispheres with regard to differences in rhythm periodicities. The expression of this laterality is dependent on the task-load level and points to a strategy of linkage and integrity in brain activity.

Circadian rhythm period in reaction time to light signals: difference between right- and left-hand side.

The study was designed to test the hypothesis that the prominent rhythm period tau of simple reaction time (SRT) and three-choice reaction time (CRT) to light signals may vary between the dominant (DH) and non-dominant (NDH) hand. Eleven healthy subjects, 8 males (16-74 years, including two left-handed) and 3 females (18-43 years), synchronized with a diurnal activity (approximately 07.00 h to approximately 23.00 h) and a nocturnal rest, volunteered for the study. A battery-powered ambulatory device was used to self-record SRT to a yellow light signal and CRT to yellow, green and red signals. Tests were performed 4-7 times/24 h during a 12- to 15-day span. Power spectra, ANOVA, cosinor, chi2 and correlation tests were used to individually analyze time series. Tau = 24 h in SRT rhythms of DH (8/11 cases) and NDH (6/11 cases) with chi2 = 3.5 and p > 0.05. In CRT rhythms, tau = 24 h for DH (8/11 cases) while tau = 8 h for NDH (7/11 cases), a difference which was statistically significant (chi2 = 9.4 with p < 0.02). Concordant results were obtained with other statistical tests leading to the conclusion that the rather complex cognitive task (CRT) and, to a certain extent, SRT of certain individuals, were associated with tau = 24 h for DH and tau = 8 h for NDH. These findings are in favor of the hypothesis that functional clocks are present in the human brain cortex, associated with the possible expression of rhythms with a prominent period differing from the right- and left-hand side.