Differential regulation of preovulatory luteinizing hormone and follicle-stimulating hormone release by opioids in the proestrous rat

We have investigated the role of mu- and kappa-opioid receptors in the central control of preovulatory LH and FSH release in the proestrous rat. Animals were anesthetized with chloral hydrate at 14:00 h on proestrus day. Following femoral artery cannulation, they were mounted in a stereotaxic apparatus. Morphine and U-50488H (benzene-acetamide methane sulphonate) were infused intracerebroventricularly either alone or in combination with naloxone and MR1452, respectively. Controls received sterile saline alone. Blood samples were obtained at hourly intervals between 15:00 h and 17:00 h. Plasma LH and FSH levels were measured by radioimmunoassay. Morphine did not significantly change plasma LH levels at 15:00 h and 16:00 h sampling intervals. A significant increase was observed at 17:00 h compared to the controls (p<0.05). U-50488H significantly increased LH levels at 16:00 h and 17:00 h (p<0.05). The co-administration of naloxone and MR1452 with mu- and kappa-agonist had no significant effect on LH levels at any sampling interval. In all groups, LH levels showed a linear rise over the sampling period between 15:00 h and 17:00 h. None of the treatments significantly altered plasma FSH levels which however, declined towards the end of the afternoon surge. In conclusion, we suggest that the secretion of LH and FSH is differentially regulated by mu- and kappa-opioid receptors. It is thought that in all groups chloral hydrate interfered with the LH surge secretory systems.

The role of heart rate in myocardial ischemia from restricted coronary perfusion

Despite many years of study, certain aspects of myocardial ischemia remain incompletely understood. One observation that motivated this study is that acute, complete occlusion produces elevations but never depression of the ST-segment potentials in electrocardiographic leads over the ischemic zone. Limited flow, on the other hand, leads to ST-segment depression, both in in situ experiments and during clinical stress tests. The prevailing biophysical theory of ischemia suggests that complete occlusion should produce at least transient ST-segment depression, a finding we have neither observed in our own studies nor uncovered in the literature. Our goal with these experiments was to understand the difference between complete occlusion and reduced coronary flow, specifically the behavior at the transition between the two. We have performed experiments by using isolated dog hearts with a cannulated left anterior descending artery suspended in a human shaped electrolytic tank. To create a range of ischemic conditions, we changed coronary flow rates both suddenly and in controlled sequences and varied the heart rate of the isolated heart. The main finding was that in the isolated heart preparation, epicardial ST-segment depression over the ischemic zone arose only under conditions of combined restricted flow and elevated heart rate. Reduced coronary flow alone never produced ST-segment depression. These findings suggest that heart rate and probably metabolic work create the conditions necessary for subendocardial ischemia that reduced flow alone cannot provoke. They furthermore suggest that the degree of ST-segment depression for a given restriction in coronary flow may depend on heart rate, which supports the notion of rate correction for clinical stress electrocardiogram testing.

Effects of pinealectomy and exogenous melatonin on serum leptin levels in male rat

The effects of pinealectomy and exogenous melatonin (N-acetyl-5-methoxytryptamine) on serum leptin levels were investigated in rats. Exogenous administration of melatonin to intact rats resulted in significant decreases in serum leptin levels (P < 0.05) compared to those of the intact control group. Serum leptin levels were significantly elevated in the pinealectomised rats in comparison to the sham-pinealectomised animals (P < 0.001) and were significantly suppressed by exogenous administration of melatonin compared to those of non-treated pinealectomised rats (P < 0.001). Hormone concentrations in the melatonin-treated pinealectomised group were found to be similar to those seen in the sham-pinealectomised group. These results suggest that pineal gland has an effect on leptin release.

Melatonin inhibits spontaneous and oxytocin-induced contractions of rat myometrium in vitro

OBJECTIVE

The aim of this study was to investigate the effects of melatonin on spontaneous and oxytocin-induced contractility of pregnant and non-pregnant rat myometrium in vitro.

DESIGN

Myometrial strips were removed from virgin or late pregnant (21 days gestation) Wistar rats following decapitation and placed in an organ bath containing Krebs' solution at 37 degrees C and pH 7.4, constantly bubbled with 95% oxygen-5% carbon dioxide and isometric contractions were recorded. Effects of cumulative concentrations of melatonin (0.1 to 10 microM) on spontaneous and oxytocin-induced contractions were studied. Possible involvement of Ca(2+)-activated K (+) channels in inhibitory actions of melatonin was investigated by using apamin (100 nM).

RESULTS

Melatonin inhibited spontaneous and oxytocin-induced contractions of myometrium from both virgin and late pregnant rats in a dose-dependent manner. After inhibition of oxytocin-induced contractions by melatonin, application of prostaglandin F (2alpha) (1 microM) but not high KCl (30 mM) containing solution initiated contractile activity. Inhibitory response induced by melatonin (13 microM) was not affected by apamin (100 nM).

CONCLUSIONS

Data from this study demonstrates that melatonin inhibits spontaneous and oxytocin-induced contractions of myometrium from pregnant and non-pregnant rats. Although the exact mechanism is not clear, melatonin-induced inhibition of myometrial contractions may results from its interactions with Ca(2+) channels.

Effects of heart position on the body-surface electrocardiogram

Previous studies have examined the influence of body position, respiration, and habitus on body surface potentials. However, the authors could only estimate the sources of the effects they documented. Among the proposed origin of changes in body surface potentials from those studies were the position of the heart, alterations in autonomic tone, differences in ventricular blood volume, and variations in torso resistivity. The goal of this study was to investigate specifically the role of geometric factors in altering body surface potentials and the electrocardiogram. For this, we used experiments with an isolated, perfused dog heart suspended in a realistically shaped electrolytic torso tank. The experimental preparation allowed us to measure epicardial and tank surface potentials simultaneously, and then reconstruct the geometry of both surfaces. Our results mimicked some of the features described by previous investigators. However, our results also showed differences that included considerably larger changes in the peak QRS and T-wave amplitudes with heart movement than those reported in human studies. We detected smaller values of root-mean-squared variability from heart movements than those reported in a human study comparing body surface potentials during change in inspiration and body position. There was better agreement with relative variability, which in these studies ranged from 0.11 to 0.42, agreeing well with an estimate from human studies of 0.40. Our results suggest that the isolated heart/torso tank preparation is a valuable tool for investigating the effects of geometric variation. Furthermore, the geometric position of the heart appears to be a large source of variation in body surface potentials. The size of these variations easily exceeded thresholds used to distinguish pathologic conditions and thus such variations could have important implications on the interpretation of the standard electrocardiogram.

Effects of paint thinner exposure on serum LH, FSH and testosterone levels and hypothalamic catecholamine contents in the male rat

We have investigated the effects of thinner inhalation on serum LH, FSH and testosterone levels together with changes in hypothalamic catecholaminergic system in the male rat. A control group inhaled normal air ventilation. The remaining animals were divided into two groups and exposed to paint thinner in a glassy cage for 15 or 30 d. Toluene concentration (the largest constituent in thinner, 66%) was set at 3000 ppm in the inhalation air. At the end, all animals were decapitated and blood samples obtained. Serum LH and FSH levels were measured by RIA and testosterone by enzyme immunoassay. Following removal of brains on dry ice, medial preoptic area, suprachiasmatic nucleus, median eminence and arcuate nucleus were isolated by micropunch technique. Noradrenaline, 3,4-dihydroxyphenylglycol (DHPG) and dopamine concentrations of these hypothalamic areas were determined by HPLC-ECD. Fifteen-day thinner inhalation significantly suppressed serum LH and testosterone levels in parallel (p<0.001) compared to control group values (LH: 0.77+/-0.07; testosterone: 2.67+/-0.39). Thirty-day exposure markedly decreased LH levels (p<0.001), but surprisingly had no significant effect on testosterone. Serum FSH levels were not significantly altered in either group. Thinner inhalation for 15 or 30 d did not cause any significant change in noradrenaline, DHPG or dopamine concentrations in the hypothalamic regions examined (except in the arcuate nucleus). These results suggest that paint thinner has an anti-gonadotropic effect and may cause long-term endocrine disturbances in the male. It is thought that the hypothalamic catecholaminergic system is not involved in thinner inhibition of LH and testosterone secretion.

Investigation of platelet aggregation by impedance and optic methods in children with iron deficiency anaemia

Although it is known that platelet count is altered in iron deficiency anaemia (IDA), the qualitative extent of this interference is not well documented. In the present study we investigated platelet aggregation (PA) by impedance and optic methods in IDA. Forty-seven patients (plasma group: 16 boys, 9 girls and whole blood group: 11 boys, 11 girls) with IDA and thirty-one healthy children (plasma group: 6 boys, 10 girls and whole blood group: 6 boys, 9 girls) were enrolled into the study. Template bleeding times were measured by the Ivy method in all children. In the control group whole blood count, serum iron levels, bleeding time and PA were determined. After basal PA was determined in the patients and controls, ferrous sulphate was orally administered to the patients at a dose of 6 mg/kg/24 h for three months. Then, PA tests were performed again in the IDA (test group) patients. Ristocetin-induced PA was suppressed in both plasma and whole blood groups. Inhibition by both collagen (p < 0.05) and ristocetin (p < 0.001)-induced PA was determined by the optic method. Similarly in PA measured by the impedance method a suppression to adenosine diphosphate (p < 0.001) and to ristocetin (p < 0.01) was found. However, no significant alteration was observed in the bleeding time. All defective responses were reversed by the iron supplementation therapy. In addition, a significant correlation was found between some parameters of PA and several haematological values. In conclusion, although defective PA responses cannot be clinically demonstrated in patients with IDA, this suppression of PA may be detected by laboratory examination. Therefore, it is advised that care should be taken when using anti-aggregant agents in IDA.

Ultrastructural interrelationship between the pineal gland and the testis in the male rat

The ultrastructural interrelationship between the pineal gland and testis was evaluated in the rat. Wistar rats were divided into 6 groups. Groups I and II were sham-orchidectomized and orchidectomized rats, respectively. Rats in group III were orchidectomized and daily injected with testosterone propionate (TP) for 1 month. Groups IV and V were sham-pinealectomized and pinealectomized, respectively. Group VI was pinealectomized and daily injected with melatonin for 2 months. All animals were anesthetized with ketamine for fixation by vascular perfusion. Pineal glands of groups I, II, and III and the testes of groups IV, V, and VI were removed and weighed. All specimens were examined by electron microscopy. Orchidectomy caused an increase of lipid droplets, cytoplasmic dense bodies, and lysosomes. Rough endoplasmic reticulum, Golgi apparatus, and mitochondria were extensive in the cytoplasm. TP administration to orchidectomized rats resulted in formation of less extensive lipid droplets and mitochondria. In pinealectomized rats, golgi complex, mitochondria, and enlarged smooth endoplasmic reticulum were extensive in the cytoplasm of Leydig cells. Formation of cytoplasmic secretory granules and osmiophilic bodies was observed. Testicular weight increased compared to group IV. Melatonin decreased testicular weight in comparison to group V and prevented ultrastructural changes. Pinealectomy and orchidectomy caused hyperactivity in Leydig cells and pinealocytes, respectively, which suggests a mutual relationship between the pineal gland and testis in the rat.

Influence of chronic morphine exposure on serum LH, FSH, testosterone levels, and body and testicular weights in the developing male rat

Opiate abuse has been a matter of serious concern in male adolescents. This study investigates the effects of chronic morphine administration on serum luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone levels, testicular histology, and body and testes weight in developing male rats. Animals were subcutaneously injected with morphine (5 mg/kg) or saline (1 mL/kg) twice daily for 30 days. Body weight determinations and injections were carried out under light ether anesthesia. At the end of the experiments, the rats were decapitated and blood samples were collected. Serum levels of LH and FSH were measured. Chronic morphine administration significantly decreased decreased serum testosterone (p < .02) and LH (p < .01) levels, but not FSH release compared to controls. Morphine exposure reduced body weight (p < .01), but had no significant effect on the testicular weight. When the testicular tissue was histologically examined, structural features of the seminiferous tubules and Leydig cells were similar in both saline and morphine-treated animals. The results suggest that opiates affect testosterone release through the hypothalamo-hypophyseal-gonadal axis rather than by a local testicular mechanism. Chronic morphine exposure during sexual maturation may have long-term endocrine disturbances in male rats.

Transient diabetes insipidus following Escherichia coli meningitis complicated by ventriculoperitoneal shunt

Although disorders of ADH secretion associated with meningitis are usually consistent with the Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH), central diabetes insipidus (DI) is an exceptional complication of meningitis. Transient DI as a complication of Escherichia coli (E. coli) meningitis due to ventriculoperitoneal shunt in an 18-month-old boy is presented. Blood and spinal fluid cultures yielded E. coli, sensitive to cefotaxime. The DI arose on the day 3 after admission and continued to the day 20. Treatment comprised cefotaxime, dexamethasone, fluid adjustment and vasopressin. The course of our case supports that in cases of bacterial meningitis, initial fluid restriction may occasionally result in dangerous conditions. Therefore, all children with bacterial meningitis should be followed closely not only in terms of SIADH but also DI. To our knowledge this is the first transient DI associated with E. coli-caused meningitis case reported.

The comparison of intraocular pressure reductions after isometric and isokinetic exercises in normal individuals

The lowering effect of physical exercise on intraocular pressure (IOP) has been reported both in healthy people and those with glaucoma, but a comparison of the lowering effect of isometric and isokinetic exercises on IOP has not been conducted in any study. Our aims were to investigate the relationship between intensity of exercise and IOP, and whether a significant difference in IOP lowering effect existed between isometric and isokinetic exercises. Sixty-seven patients with an age range of 23-40 who had no ocular disease were randomly divided into two groups. While 31 patients in the first group, group A, performed isokinetic exercise with the Cybex 6000 dynamometer, 32 patients in the second group, group B, had isometric exercises with the same machine. IOP was measured in the right eye of patients with Shiotz tonometer just before and 10 min following exercise. Exercise intensity and total energy consumption were determined by the machine for each patient. While IOP values measured before exercise, the degree of exercise applied, and total energy consumption did not differ significantly between groups, both isometric and isotonic exercises lowered IOP significantly. As a result, isometric and isokinetic exercises lowered IOP in ophthalmologically normal subjects with direct relationship to exercise intensity and total energy consumption. Since the pressure lowering effect of isokinetic exercise was more significant, it might prove useful to glaucomatous patients.

Effect of antibiotics and anti-inflammatory agents on the purified protein derivative response in the rat

We investigated the effects of several antibiotics and anti-inflammatory agents on the purified protein derivative (PPD) response in the rat. Animals were immunized with Mycobacterium bovis vaccine BCG. Antibiotics and anti-inflammatory drugs were administered at therapeutic doses for 10 d. Chloramphenicol, erythromycin, aspirin and ibuprofen suppressed the PPD response, but penicillin and acetaminophen had no significant effects.

A retrospective comparison of allogeneic peripheral blood stem cell and bone marrow transplantation results from a single center: a focus on the incidence of graft-vs.-host disease and relapse

To detect the effect of the stem cell source, allogeneic peripheral blood stem cell transplantations (alloPBSCTs) performed between 1995 and 1997 from human leukocyte antigen (HLA)-identical siblings in 40 patients with acute and chronic hematological disorders were compared with a historical group of 40 patients with similar variables who had received allogeneic bone marrow transplants (alloBMTs) between 1993 and 1995. Patients in both groups were identical except that both the recipient and the donor ages were, on average, higher in the alloPBSCT group (26 vs. 36 [p = 0.005] and 27 vs. 32 [p = 0.024], respectively). Patients received similar therapy excluding posttransplant granulocyte colony-stimulating factor administration (97% in alloBMT vs. 12.5% in alloPBSCT). The median time to reach neutrophil counts >0.5 x 10(9)/L and platelet counts >20 x 10(9)/L was 13 and 14 days, respectively, in patients receiving alloPBSCTs compared with 19 and 27 days in patients receiving alloBMTs (p = 0.0014 and p = 0.0002). The alloPBSCT group required similar transfusions of red blood cells or platelets. The incidence of grade II-IV acute graft-vs.-host disease (aGVHD) was similar in both groups. However, chronic GVHD (cGVHD) of all grades developed in 78.1% of patients in the alloPBSCT group after a median follow-up period of 12.5 (range 0.5-34) months. In alloBMT recipients, cGVHD of all grades developed in 21.4% after a median follow-up period of 38 (range 0.5-62) months (p = 0.00001). Day 100 transplant-related mortality was also similar: 20% (8 of 40) in the alloBMT patients and 17.5% (7 of 40) in the alloPBSCT group. Although not statistically significant, a relatively higher relapse rate occurred in the alloBMT group (21.4 vs. 10.7%). The estimated disease-free survival in month 24 was 51.3% for alloBMT and 54.6% for alloPBSCT, and the estimated overall survival in month 24 was 56.1% for alloBMT and 64.6% for alloPBSCT. In conclusion, this retrospective comparison suggests that alloPBSCT from HLA-identical donors is associated with faster engraftment, fewer transfusions, and no greater incidence of aGVHD, but a high incidence of cGVHD.

Effects of mu, kappa, and delta opioid receptor agonists and antagonists on rat hypothalamic noradrenergic neurotransmission

We have investigated the effects of specific mu-, kappa-and delta-opioid receptor agonists and antagonists on the hypothalamic noradrenergic neurotransmission and on luteinising hormone (LH) release in the ovariectomised and steroid-primed rat. The opioid agents were infused intracerebroventricularly under ketamine anaesthesia and blood samples collected at hourly intervals on the afternoon of the anticipated LH surge. At the end of the experiment, the rats were decapitated and the medial preoptic area, suprachiasmatic nucleus, median eminence and arcuate nucleus surgically isolated by micropunch. The concentrations of noradrenaline (NA) and its metabolite (3,4-dihydroxyphenylglycol; DHPG) in these samples was determined by high performance liquid chromatography with electrochemical detection. Plasma LH levels were measured by radioimmunassay. The three opioid agonists reduced concentrations of NA and DHPG in all four hypothalamic areas. These inhibitory effects of the opioid agonists were mostly prevented following coadministration with their respective antagonists. However, naloxone had no significant effect on DHPG levels in any of the hypothalamic regions examined. Plasma LH levels were found to be either low or undetectable in all groups. These results suggest that mu-, kappa- and delta-opioid receptors have inhibitory influence on the hypothalamic noradrenergic neurotransmission around the time of the LH surge. It is thought that the ketamine anaesthesia interfered with LH release.

Effects of DPDPE (a specific delta-opioid receptor agonist) and naloxone on hypothalamic monoamine concentrations during the pre-ovulatory LH surge in the rat

We have investigated the inter-relationship between the opioid and aminergic systems in the control of secretion of the pro-oestrous LH surge and the involvement of delta-opioid receptor subtypes in this process. Conscious female rats bearing a cannula in the femoral artery were injected i.p. with a selective delta-opioid receptor agonist (DPDPE) either alone or with the opioid antagonist (naloxone) at 1300 h on the day of pro-oestrus. Blood samples were collected hourly between 1500 h and 1900 h, and plasma LH levels were measured by RIA. At the end of this period (1900 h), the animals were autopsied and the concentrations of the amines (noradrenaline (NA), dopamine (DA), 5-hydroxytryptamine (5HT)) and their metabolites (dihydroxyphenolglycol (DHPG) and 5-hydroxyindoleacetic acid (5HIAA), metabolites of NA and 5HT respectively) were determined by HPLC with electrochemical detection in the medial preoptic area, suprachiasmatic nucleus, median eminence and arcuate nucleus. DPDPE abolished the LH surge and concomitantly decreased hypothalamic NA and DHPG concentrations in all the areas examined. The levels of DA, 5HT and 5HIAA were also reduced in all hypothalamic regions studied, except DA and 5HIAA in the suprachiasmatic nucleus. Naloxone reversed these inhibitory effects of the delta-agonist. We conclude that activation of delta-opioid receptors may exert an inhibitory effect on LH release. The effect is probably an indirect one mediated by the monoaminergic systems, as they are suppressed by DPDPE in nearly all the hypothalamic regions studied.

Effects of hematoma on the short-term fate of experimental microvenous autografts

The early effects of hematoma on the healing pattern of interpositional vein grafts were studied in 60 rats. In all animals, vein grafts approximately 10-mm in length were used to bridge defects created in the femoral artery and vein on the same side, with a 1:1 graft-to-host diameter match. Grafted vessels were completely covered with hematoma and separated from the surrounding tissue in 30 animals, while the other 30 rats served as controls. Both groups were divided into six subgroups of five animals each, according to the age of the grafts: 1, 3, 5, 7, 14, and 21 days. Graft patency and healing were assessed both clinically and histologically 20/30 (66.6 percent) of the interarterial and 27/30 (90 percent) of the intervenous vein grafts in Group 1 (hematoma group), and 28/30 (93.3 percent) of the interarterial and 29/30 196.6 percent) of the intervenous vein grafts in Group 2 (controls) were found patent. The patency rate of the interarterial vein grafts in the hematoma group was statistically significantly lower than in the control group and than in the intervenous vein grafts of the same group (p<0.005). The majority of interarterial vein-graft failures occurred after postoperative day 7 in Group 1. Patent specimens were examined under scanning electron and light microscopy. The authors concluded that perivascular hematoma caused spasm and flow disturbance, prolonged vessel-wall ischemia, and severe vessel-wall injury in the arterial circulation of the microvenous grafts. It also delayed the healing process and subjected the grafts to the development of occlusive mural thrombus. In contrast, the healing pattern of the intervenous vein grafts was not markedly influenced by perivascular hematoma, and equilibrium between thrombogenic and antithrombogenic factors on the graft surface was restored over a short period of time.

Contraction of experimental skin flaps

Contraction of experimental skin flaps in loose-skinned animals is a well-known but underestimated phenomenon that in fact may vary in different circumstances and complicate the calculations of survived and necrosed areas. A standard abdominal island skin flap design in the rat was used in this study to investigate the difference between the contraction rates of necrotic and survived tissues, and to determine its significance in the experimental models. The abdominal island skin flap was based on the inferior epigastric neurovascular bundles, and it extended from the pubis to the xiphoid and between the both midaxillary lines. The study was conducted in two steps. In the first step, contraction rates of completely necrosed (both pedicles severed) and completely survived (vascular pedicles were intact on both sides either with or without a nerve supply) flaps were assessed in 45 animals. After 1 week, area loss was highly significant in both necrosed and survived flaps (p < 0.001). The rate of contraction was significantly higher in necrosed tissues than in survived tissues (p < 0.001), and it was also significantly higher in the neurovascular flaps than in the denervated flaps (p < 0.05). The contraction of all flaps occurred in the vertical dimension, whereas the horizontal dimension stayed almost the same. In the second step of the study, a unilateral, pedicled abdominal flap was used, which had a constant necrotic zone on the nonpedicled half, either with or without a nerve supply in 30 animals. After 1 week the pedicled halves of all flaps were significantly larger than the nonpedicled halves (p < 0.001). Although the total area loss was higher in the neurovascular flaps than the denervated flaps, the difference was not significant statistically (p > 0.05). There was no statistically significant difference between the areas of necrosis seen in both groups when it was expressed as a proportion of the total flap area (p > 0.05). However, this insignificant difference became significant when the amount of necrosis was expressed as a proportion of only the nonpedicled flap half, favoring the denervated flaps (p < 0.005). It appears in this study that ultimate proportions of surviving and necrosed tissues may be inconsistent owing to the variable contraction rates of these tissues, and misleading conclusions may appear during the assessment of given treatment modalities.

Nerve and tendon approximator

A practical and simple approximating device, made from a plastic syringe and 2 needles, is described. It allows a safe, tension-free approximation of severed ends of nerves or tendons.

An investigation on plasma progesterone levels during pregnancy and at parturition in the Ivesi sheep

In this study, plasma progesterone concentrations in a total of 45 Ivesi sheep were investigated during pregnancy and at parturition. Blood samples were collected from all the sheep studied every 20 days commencing on the 30th day of pregnancy. Plasma progesterone levels were determined by radioimmunoassay. During the second half of the pregnancy, progesterone concentrations in the sheep giving birth to one, two and three lambs were 2.02 +/- 0.08 ng/ml, 3.24 +/- 1.18 ng/ml and 4.90 +/- 0.85 ng/ml, respectively. There was no significant variation in progesterone levels between sheep with male and female offspring. At parturition, plasma progesterone concentrations did not differ significantly between the animals. The present results indicate that plasma progesterone levels could be used not only to determine the pregnancy status of the animal but also to predict the number of fetuses after the second half of the pregnancy.