Dynamic change in plasma leptin level during the perioperative period

OBJECTIVE: To examine the association of plasma leptin level with insulin, which is known as a metabolic regulator of leptin, and various stress-related factors during the perioperative period. METHODS: Thirty-one patients undergoing gastrectomy were enrolled and blood samples were obtained preoperatively, intraoperatively, immediately after operation, and on the first and second postoperative days. RESULTS: The plasma leptin level showed a triphasic response. Immediately after operation, the leptin level was the lowest, while the serum cortisol and interleukin-6 (IL-6) levels had their peak (PHASE 1). On the first postoperative day, the leptin level had its peak with the serum cortisol and IL-6 level remaining elevated (PHASE 2). On the second postoperative day, while the serum cortisol and IL-6 levels still remained elevated, the plasma leptin level fell to the preoperative value (PHASE 3). The plasma leptin level correlated well with the insulin level at all time points during the study period. CONCLUSION: Our results suggest a possible role of leptin in harmonizing neuroendocrine and immune responses with energy balance.     

Time-dependent variations of transcutaneous PCO2 level in normal subjects

Transcutaneous PCO2 (PtcCO2), which is linearly related to arterial PCO2, was continuously recorded in healthy, adult, normal volunteers for 8-h periods. Recording this variable with the apparatus employed permits measurement of changes in the level of ventilation while subjects are freely ambulant and unencumbered by invasive and flow-resistive respiratory apparatus. The time series obtained exhibited marked periodicities. The frequencies and amplitudes varied between subjects. Peak-to-peak variation was 10-20% of mean values. There was no apparent association between fluctuations in PCO2 and activity other than formal exercise. Visual inspection of the time series and preliminary statistical analysis of digitally converted data suggested that the time-dependent changes of PtcCO2 were normally distributed. However, more rigorous statistical examination revealed that in no case was PtcCO2 actually normally distributed.     

Diurnal rhythm of plasma immunoreactive corticotropin-releasing factor in normal subjects

Plasma corticotropin-releasing factor (CRF), corticotropin (ACTH) and cortisol levels were simultaneously determined by radioimmunoassays at 0600 h, 1200 h, 1800 h and 2200 h in six normal subjects, in order to examine whether the diurnal rhythm in plasma CRF exists and how it correlates to the diurnal rhythm in plasma ACTH and cortisol concentration. The highest CRF level was observed at 0600 h (7.0 +/- 1.2 pg/ml) and significantly lower levels (p less than 0.01) at 1800 h (1.7 +/- 0.2 pg/ml) and 2200 h (1.9 +/- 0.4 pg/ml). A clear diurnal rhythm was demonstrated in plasma ACTH and cortisol levels, with the highest values at 0600 h (44.6 +/- 8.1 pg/ml and 15.9 +/- 2.0 micrograms/dl, respectively) and the lowest at 2200 h (12.3 +/- 2.8 pg/ml and 4.6 +/- 1.0 micrograms/ml, respectively). These results suggest that the diurnal rhythm in ACTH and cortisol is under the regulation, at least in part, of the diurnal rhythm in CRF secretion.     

Simultaneous administration of TRH and sulpiride caused additive but not synergistic PRL responses in normal subjects.

In order to study the mode of action of TRH and sulpiride in man, we administered TRH (500 micrograms, iv) and sulpiride (DA D2 receptor antagonist, 100 mg, im) simultaneously to 6 normal females (20-21 yr). Normal females showed significantly greater PRL increments and AUC in response to the combined administration compared to a single administration of each agent (P < 0.05-0.01), while the increment and AUC in response to the combination did not exceed the sum of those responses to a single administration. In contrast, the combined administration of TRH and sulpiride did not elicit an enhanced response of plasma TSH. These results indicate that the sites of action of TRH and sulpiride might be different from each other, and these agents work additively with no interaction in human lactotrophs.     

Evaluation of the circadian profile of peripheral plasma galanin concentrations in normal subjects

Galanin administration can influence pituitary function principally resulting in an increase in GH secretion. However, the role of circulating GAL levels in human endocrine function is still unknown. In the present study we simultaneously measured the circadian profiles of GAL, ACTH and GH in peripheral blood of ten adult subjects. Plasma samples were collected through an intravenous catheter at 0800, 1200, 1600, 2000, 2200, 2400, 0200, 0400 hours. The results were statistically evaluated by the cosinor analysis technique. A significant circadian rhythm of both plasma ACTH (p < 0.001) and GH levels (p < 0.03) was found with acrophases occurring at 0753 hrs and 0131 hrs for ACTH and GH, respectively. On the contrary, no significant rhythm was found in plasma GAL levels, indicating that no correlations exist between GAL and either GH or ACTH circadian profiles. Furthermore, the simultaneous assay of both GAL and GH plasma levels during a nocturnal frequent sampling performed in four volunteers showed the presence of peaks in GAL levels which, however, were not concomitant to the peaks in GH levels. These data demonstrate the lack of rhythmicity in the circadian profile of plasma GAL levels in healthy human subjects. The role of GAL in human endocrine function remains unknown and these results suggest that, in spite of the well documented increase in plasma GH concentrations following the intravenous administration of GAL, physiologically circulating levels of GAL are likely not involved in the regulation of GH secretion.     

Characteristics of the early recovery period and the level of carbohydrate-lipid metabolic substrates after 24-hour immobilization hypothermia

The peculiarities of 24-hour hypothermia were studied in rats during immobilization and a 5-hour recovery period. The levels of glucose in blood and liver, glycogen in liver, skeletal muscles and heart, total lipids in liver and blood, nonesterified fatty acids in blood have shown that the speed of rewarming is limited both by the level of carbohydrate and lipid energy substrates.     

Circadian rhythm of the PRL response to TRH in healthy subjects

The PRL response to TRH constitutes an important clinical tool for diagnosing forms of hyperprolactinemic syndrome. Hence it is important to establish the characteristics of the circadian variation in the response of PRL to TRH to improve the diagnostic value of the test. Six male subjects, ranging in age from 23 to 24 years, participated in this study. All were considered healthy on the basis of clinical examination, biochemical and hormonal tests. Six TRH tests were performed on each subject, one test every other day during a total span of 12 days. Each test was performed at a different clock hour: 0000, 0400, 0800, 1200, 1600, 2000. For the test, subjects received 200 microgram TRH intravenously. Blood samples were drawn from a catheterized arm vein before the TRH injection (basal value) and 20, 30, 60 and 120 min after injection. At each timepoint 5 endpoints were determined for PRL on each subject. The population mean cosinor, according to Halberg, was used to investigate the circadian rhythm in each of the endpoints. All the 5 endpoints for PRL are consistent on showing p values near 0.5 and acrophase estimates before midnight (while basal value displays acrophase at 0400). Further investigations are necessary to clarify these circadian rhythms and the shift of the acrophases.     

LHRH increases plasma 7B2 concentration in normal human subjects

We studied the response of plasma 7B2 to LHRH and ovine corticotropin releasing hormone (o-CRH) in healthy young subjects. The plasma 7B2 concentration significantly increased from 78.3 +/- 7.5 (mean +/- SEM) to 102.0 +/- 6.0 ng/L (142.7 +/- 12.7% of the basal value; P less than 0.01) following iv administration of LHRH in seven young subjects. On the other hand, no increase in plasma 7B2 was found after iv administration of o-CRH in six young subjects. These results, together with our previous report of no increase in plasma 7B2 after administration of TRH and GHRH in young subjects, suggest that pituitary 7B2 may be present in gonadotrophs and be released only by LHRH in physiological conditions.     

Relationship between plasma renin activity and physical fitness in normal subjects

The relationship between plasma renin activity (PRA) at rest and physical fitness was studied in 40 normal young subjects on a liberal sodium intake. Plasma renin activity was measured in arterial blood withdrawn at the end of a 30-min period of rest in recumbency, while physical fitness was expressed by the highest oxygen uptake achieved during an uninterrupted graded exercise test performed in the sitting position on an electromagnetically braked ergometer bicycle (peak VO2). Log PRA correlated significantly and inversely with peak VO2 adjusted for body weight (r = -0.34; P less than 0.05) in single regression analysis. Using multiple regression and adjusted peak VO2, age, urinary sodium excretion and mean intra-arterial pressure as independent variables, no combination of two or more independent variables yielded significant partial correlation coefficients with log PRA. This correlation suggests that PRA at rest is inversely related to the subject's physical fitness.     

Posthypoxic changes in the cerebral cortex of dogs in the late recovery period after 4-hour hypovolemic hypotension]

On the 14th-21st day of the restorative period after four-hour hypovolemic hypotension the level of total RNA decreased in the tissue of the gray matter of the brain by 20.9%, and of DNA-by 13%. In the postmitochondrial supernatant the concentration of prealbumins was reduced by 26.5%, alpha-globulins--19.2%, gamma-globulins--by 59.8%; the concentration of albumins and beta-globulins was increased by 12.6% and 50.0%, respectively. The activity of acid cathepsins rose by 50%, and of acid phosphatase--by 44%. The activity of total lactic dehydrogenase (LDH) and glutamic dehydrogenase failed to differ essentially from the control level. However, LDH isoenzyme spectrum changes towards the reduction of LDH3+4+5 from 31.9 to 14.2%. Analysis of densitograms of electrophoresis in polyacrylamide gel showed physico-chemical changes in the protein molecules similar in nature to the denaturation phenomenon. The Purkinje's cell count decreased in the cerebellum by 41.3% in comparison with control.