Terminal nerve sprouting at the frog neuromuscular junction induced by prolonged tetrodotoxin blockade of nerve conduction

The effects of a prolonged blockade of nerve conduction by tetrodotoxin on frog motor innervation were studied in the cutaneous pectoris muscle of Rana esculenta. Prolonged nerve blockade (up to 22 days) was obtained by repeated subperineural injections of tetrodotoxin. Changes in morphological parameters of neuromuscular junctions were investigated in muscles after staining with a combined cholinesterase-silver method. In addition, changes in the incidence of polyneuronal innervation were investigated conjointly by electrophysiology and morphology. Morphometric analysis of singly innervated muscle fibres of 60 microns diameter revealed insignificant changes during the first week of tetrodotoxin-nerve blockade. After 15 days of paralysis, the mean length of synaptic contacts and the mean length of terminal arborization per synapse were significantly increased as compared to controls (contralateral muscles and citrate buffer-injected controls). After 20-22 days, differences in synaptic and aborization mean lengths were accentuated and reached 44 and 43%, respectively. At that time, the mean number of terminal branching points and of continuous synaptic contacts were also significantly increased (around 20 and 50%, respectively). No changes in the length of abandoned gutters were observed. The incidence of focal polyaxonal innervation (detected morphologically) and of polyneuronal innervation (determined electrophysiologically) was unchanged. The results show that prolonged tetrodotoxin blockade induces sprouting of the terminal arborization which results in an extension of pre-existing nerve terminals and an increase in the complexity of terminal arborization by addition of new branches. Nodal (collateral) sprouting was not changed.

Sprouting of frog motor nerve terminals after long-term paralysis by botulinum type A toxin

A single sublethal injection of botulinum type A toxin (BoTx-A) to winter frogs induced a general and complete paralysis of skeletal muscles, which lasted several months. Quantitative analysis of 483 end-plates from 8 BoTx-A poisoned muscles and 495 endplates from 8 control muscles revealed a higher and significant incidence of terminal and ultraterminal sprouts in poisoned junctions when taking into account the normal remodelling of motor innervation. We conclude that prolonged neuromuscular blockade by BoTx-A results in the extension of the nerve terminal arborization.

Measurement of parathyrin in blood from thyroid veins: two radioimmunoassays compared in patients with primary hyperparathyroidism

We measured parathyrin (PTH) in peripheral venous blood samples and in thyroid veins (both homolateral and contralateral to the lesion) in 13 patients with surgically confirmed parathyroid adenomas. Two different RIAs were used, one specific to the mid-region of the molecule (44-68, M-PTH), the other specific to the carboxy-terminal region (65-84, C-PTH). With the M-PTH assay we established a statistically significant multiple correlation (P less than 0.05) between the PTH concentrations in blood from the peripheral and thyroid veins; no significant correlation was found when we used the C-PTH assay. Our results confirm the superiority of the M-PTH RIA over the C-PTH RIA for study of hormonal secretion in primary hyperparathyroidism.

Measurement of parathyrin in blood from thyroid veins: two radioimmunoassays compared in patients with primary hyperparathyroidism

We measured parathyrin (PTH) in peripheral venous blood samples and in thyroid veins (both homolateral and contralateral to the lesion) in 13 patients with surgically confirmed parathyroid adenomas. Two different RIAs were used, one specific to the mid-region of the molecule (44-68, M-PTH), the other specific to the carboxy-terminal region (65-84, C-PTH). With the M-PTH assay we established a statistically significant multiple correlation (P less than 0.05) between the PTH concentrations in blood from the peripheral and thyroid veins; no significant correlation was found when we used the C-PTH assay. Our results confirm the superiority of the M-PTH RIA over the C-PTH RIA for study of hormonal secretion in primary hyperparathyroidism.

Electrophysiological and morphological study of polyneuronal innervation in the cutaneous pectoris muscle of adult frog (Rana esculenta)

The incidence of polyneuronal innervation in the cutaneous pectoris muscle of the adult frog, Rana esculenta, was determined quantitatively using electrophysiological and morphological techniques. The mean percentages of multiple innervated endplates obtained with both techniques from a series of 19 muscles examined at all times of the year were in very good correlation: 30.7% (196/639 endplates) by electrophysiology and 30.5% (478/1569 endplates) by morphology. In nine muscles examined during the period from December to March the mean percentages, 36.8% (110/299) by electrophysiology and 38.6% (281/727) by morphology, were significantly higher than those obtained for 10 muscles investigated during the period from May to November, 25.3% (86/340) and 23.4% (197/842) with both techniques respectively. The higher incidence of collateral sprouted branches detected at polyinnervated endplate sites in muscles of winter frogs might be related to these seasonal variations. Most of the 1688 fibres from 26 muscles examined throughout the year exhibited one centrally located endplate. However, around 11% of them were found to be innervated at two separate endplate sites. Muscle fibres exhibiting this type of innervation were invariably the largest fibres in each muscle tested, having an apparent diameter greater than 48 micron. The distance between the endplates of these fibres represented between 10 and 30% of their total length. No significant seasonal variations were observed in the incidence of these dually innervated fibres. In conclusion, both electrophysiological and morphological results show that the normal incidence of polyneuronal innervation in the cutaneous pectoris muscle of adult Rana esculenta is affected by seasonal related factors which influence the nodal sprouting activity. Moreover, they show that a dual pattern of innervation is a common feature in large fibres of this muscle.

Ontogeny of susceptibility to experimental febrile seizures in rats

Two experiments were conducted using microwave hyperthermia (MHT) to induce seizures among limited numbers of Long-Evans rat pups. The MHT model of febrile seizures eliminates several methodological complications inherent in previous animal models of the disorder. In Experiment 1, rat pups were rendered hyperthermic with MHT or were sham-irradiated on Days 11, 13, 15 or 17 postpartum. The results indicate a statistically significant decline in seizure susceptibility with age. In Experiment 2, rats were subjected to either single or multiple hyperthermic episodes on Days 11, 13, 15, or 17 postpartum. The results indicate an increase in susceptibility to seizures attributable to prior seizure history. In both experiments, seizures were induced with increases in rectal temperature of 1 to 3 degrees C. The results parallel many clinical features of febrile seizures and argue the efficacy of the MHT model.

The effect of phenytoin on the magnitude and duration of neuromuscular block following atracurium or vecuronium

Patients chronically receiving anticonvulsants have been reported to be resistant to the long-acting competitive neuromuscular blockers. This study examines the effects of atracurium and vecuronium on 100 neurosurgical patients; 50 receiving chronic phenytoin therapy (group I) and 50 controls (group II). During O2/N2O/halothane anesthesia, five patients in each group were given a bolus of vecuronium 0.1 mg/kg, and a different five patients in each group were given atracurium 0.5 mg/kg, to produce neuromuscular blockade in excess of 95%. The time to maximum blockade and the recovery from atracurium was unaffected by phenytoin therapy. Recovery from vecuronium was enhanced in the phenytoin group, as demonstrated by the recovery index, defined as the time required for recovery from 25-75% of the control neuromuscular response (7.9 +/- 2.2 min compared with 17.8 +/- 5.1 min in controls, P less than 0.005). Similarly, the total duration of neuromuscular blockade, defined as recovery to 90% of control response, was significantly shorter in the phenytoin group (31.9 +/- 6.0 min compared with 69.7 +/- 12.9 min in controls, P less than 0.001). The remaining 40 patients from each group were given a preselected dose of either vecuronium (0.02-0.06 mg/kg) or atracurium (0.10-0.25 mg/kg) during anesthesia with O2/N2O/fentanyl, to generate dose-response curves for the relaxants. Using analysis of covariance, the slopes and elevations for atracurium were found to be essentially identical in the two groups; as were the calculated ED50 and ED95. Patients receiving chronic phenytoin therapy were resistant to vecuronium-induced neuromuscular blockade. With vecuronium, the dose-response curves for the two groups were parallel; the curve for phenytoin patients was shifted to the right.(ABSTRACT TRUNCATED AT 250 WORDS)

Structural responsiveness of filamentous bacteriophage Pf1: comparison of virion structure in fibers and solution. The effect of temperature and ionic strength

X-ray diffraction from fibers and magnetically oriented solutions has been used to study the effect of changes in environment on the helical symmetry and radial structure of the Pf1 virus particle. Detailed analysis of equatorial scattering to a spacing of 8-10 A was used to identify small radial motions of structural elements in the virus particle. R-factor ratios were used to determine the statistical significance of observed changes. Comparison of the structure of virus particles in fibers with those in solution indicated that the helical symmetry of the virions remains unchanged during fiber formation. In most fibers the virions appear to be slightly distorted by the tight packing of virus particles. This distortion results in an apparent increase in the radius of the virus particle of approximately 0.6 A. A change in the radius of the DNA is also observed. Increase in the concentration of solvent molecules during fiber formation results in penetration of the virus interior by some solvent components. NaCl is also able to enter the virus interior. The change in the helical symmetry of the virions at approximately 8 degrees C appears to be the same whether observed by diffraction from fibers or from solutions. Only subtle changes in radial structure are associated with the temperature transition.

Long-term effects on adiposity after preweaning nutritional manipulations in the gastrostomy-reared rat

Male Long-Evans rat pups were either fed by continuous intragastric infusion of a milk formula to match the growth rate of their normally reared siblings, or overfed by continuous infusion of a fat-supplemented formula from d 4 through d 18 postpartum. The early overfeeding accelerated growth and the overfed rats remained significantly heavier than normally reared siblings as adults. Early overfeeding with this procedure led to an adult obesity at 14 mo characterized by significantly larger epididymal and retroperitoneal fat depots resulting from an increase of both fat cell size and number, and by an increase in adipose tissue lipoprotein lipase activity. Gastrostomy rearing per se, without overfeeding, resulted in adult rats that weighed the same as normally reared siblings but had significantly larger retroperitoneal fat depots because of more adipocytes. These findings suggest that the quantity of food consumed during early growth and development, and the quality of early nutrition and/or the early rearing environment affect adipose tissue development and have long-term consequences that persist in the rat.

An improved combined cholinesterase stain and silver impregnation method for quantitative analysis of innervation patterns in frog muscle

The original method combining Karnovsky's cholinesterase stain and Bodian silver impregnation has been modified to stain both myelinated and unmyelinated axons and to reduce background staining. The improvements were obtained by adding nitric acid to a paraformaldehyde-acetone fixative and by carrying out the silver impregnation of axons in an alcoholic solution. The method is especially suitable for quantitative estimation of the different kinds of nerve sprouting as well as for study of the remodeling of neuromuscular junctions in normal and experimental frog muscles.

Two years of intrauterine contraception with levonorgestrel and with copper: a randomized comparison of the TCu 380Ag and levonorgestrel 20 mcg/day devices

IUDs releasing 20 mcg/day of levonorgestrel (LNg20) were in randomized trial together with the Copper T, model TCu 380Ag, in seven centers involving 2244 women. Two-year (25 months) gross cumulative pregnancy rates were 0.2 +/- 0.2 and 0.9 +/- 0.3 for the levonorgestrel and copper releasing devices, respectively (P greater than 0.05). There were no ectopic pregnancies in more than 1600 woman-years of use of each device. Removal rates for bleeding and/or pain or for medical reasons other than menstrual problems did not differ significantly between devices. Oligomenorrhea or amenorrhea prompted 10.7 per hundred (gross rate, 8.4 net rate) women using the LNg 20 IUD to request removal in the two-year period, significantly above the 0.2 per hundred rate among women with the Copper IUD (P less than 0.001). At the end of two years an estimated 59.4 per 100 women were continuing use of the LNg 20 IUD, and 67.5 per 100 (P less than 0.001) with the TCu 380Ag. This difference is almost wholly ascribable to a marked reduction in bleeding episodes and days among women using the LNg 20 device with concomitant removal of device. Hemoglobin rose an average of 0.5 g/dl (P less than 0.001) for this group whereas women using the TCu 380Ag experienced a decline of 0.2 g/dl compared with baseline values (P less than 0.001).

Characteristics of growth hormone response to the administration of growth hormone-releasing hormone (GRF) in the lamb

Human growth hormone releasing hormone (GRF 1-44 or GRF 1-29) was administered to lambs at two different physiological stages (suckling: 5-6 week-old and weaned: 14-15 week-old) when growth hormone (GH) secretory patterns were different: suckling lambs exhibited flat basal GH profiles (5-10 ng/ml) while the weaned lambs had frequent spontaneous episodes of GH release (15-65 ng/ml). The iv injection of GRF evoked an immediate release of GH. In each case, plasma GH levels reached a maximum 1-4 min after the injection. The secretory spike was multiphasic and lasted 30-60 min. Administration of GRF (0.1 microgram/kg) in weaned lambs induced GH pulses with an amplitude comparable to that of endogenous peaks. The induction of a GH peak occurred even when a spontaneous peak immediately preceded the GRF injection. Also, spontaneous peaks were observed during the hour following a GRF-induced GH peak. In suckling lambs, GRF injected intravenously as a single bolus in a range of 0.01 to 0.5 microgram/kg (2 to 100 pmoles/kg) stimulated GH release in a dose-dependent manner. Chronic administration of GRF (0.75 nmole GRF 1-44 or GRF 1-29 per kg twice daily for 21 days) in newborn lambs increased significantly (p less than 0.001) the acute response to GRF during the course of the treatment. GH response to GRF 1-44 and GRF 1-29 was the same. These data show that lambs are highly responsive to GRF action during both suckling and weaning and suggest that there is no in vivo desensitization of the pituitary gland after acute or chronic GRF administration.

Results of in vitro fertilization attempts in women 40 years of age and older: the Norfolk experience

Twenty-nine patients 40 years of age or older were stimulated with gonadotropins, starting on day 3 of the cycle, in a total of 64 cycles (January 1983 to June 1985) for multiple follicular development for in vitro fertilization. Most patients' infertility was due to tubal disease (n = 8) or pelvic endometriosis (n = 14). The mean number of preovulatory and immature oocytes recovered per laparoscopy was 2.53 +/- 1.73 and 1.57 +/- 1.58, respectively. There were no statistically significant differences between the number of preovulatory and immature oocytes harvested, fertilized, or transferred in this group and the number in patients younger than 40 years of age. No statistically significant differences were observed between peripheral estradiol and progesterone levels in patients 40 years of age or older and levels in patients 39 years of age or younger. There were 15 pregnancies in this group of patients, for a pregnancy rate of 23.4% per stimulated cycle, 27.7% per laparoscopy, and 29.4% per transfer. The ongoing pregnancy rate (12%) was lower, and the total abortion rate (60%) was higher, in patients 40 years of age or older in comparison with patients 39 years of age or younger. Patients 40 years of age or older should be counseled regarding the high abortion rate in this group.

Preliminary experiment with computerized anamnesis in gynecology and reproductive health

The Hospital of the Faculty of Medical Sciences of the State University of Campinas is implementing an Integrated Health Care Programme, whose objectives are early detection of risk factors of several diseases and the evaluation of the patient's reproductive health at the moment of the first visit to the Hospital. The initial results of this program encouraged us to try to apply it all to our own clientele. The present lack of material resources and qualified manpower leads us to concentrate all our attention on the patient's immediate complaints. This situation indicated to us that the only way to implement the program should be by means of a computerized questionnaire able to detect diseases and risk factors early. This paper presents the preliminary results of the application of computerized questionnaires to evaluate health risks. The authors conclude: The application of a computerized questionnaire met with very favorable reception by the clientele; In some segments of the population, the questionnaire can be answered by the patients in direct interaction with the computer; Programmes which evaluate risk factors need to be carefully revised before being put to use; The system operates on a relatively low cost basis, which could bring undeniable benefits to primary health care.

Ontogenetic changes in vasopressin binding site distribution in rat brain: an autoradiographic study

Binding sites for [3H]vasopressin were identified in brains of neonatal (days 0-23) and adult (90 day) Long-Evans and Brattleboro rats, using a technique of in vitro receptor autoradiography. Results indicate that the regional distribution of binding sites for [3H]vasopressin in the brain changes markedly during postnatal development. Binding sites in the septum proliferated slowly to attain adult distribution in the dorsal and lateral septum, while in other regions, such as the caudate, hippocampus and cingulate gyrus, intense labeling appeared early in development but disappeared by adulthood. In the amygdala, binding did not change during postnatal development. Binding sites in the septum appeared before vasopressinergic fibers are present. Also, binding was present for vasopressin in regions which have not yet been reported to receive vasopressinergic innervation. Therefore, it is proposed that the presence of binding sites for vasopressin is independent of the presence of vasopressin itself. This hypothesis is supported by labeling in the Brattleboro rat which was comparable to that in the Long-Evans.

Pepstatin analogues as novel renin inhibitors

Pepstatin analogues corresponding to the general formula A-X-Y-Sta-Ala-Sta-R were synthesized in solution phase. Various changes in the nature of the A, X, and Y groups were made to improve the inhibitory potency against human plasma renin activity. The results were interpreted by use of the active-site model based on the sequence of human angiotensinogen. The tert-butyloxycarbonyl group and the isovaleryl group were found to be the most effective acyl groups (A). The analogues having a Phe residue in place of Val1 (X) and His or amino acid with an aliphatic side chain such as norleucine or norvaline in the Y position showed the highest inhibition of human plasma renin activity with IC50 values of about 10(-8)M. Esterification or amidification of the carboxyl group of the C-terminal statine did not change the inhibitory potency. The selectivity for rat, dog, pig, and monkey plasma renin of the most interesting compounds was studied.

Influence of taste stimulation during the suckling period on adult taste preference in rats

Effects of taste deprivation and selective taste exposure during the suckling period on adult preference for flavored solutions was examined. Taste deprivation was achieved by rearing rat pups "artificially," in individual cups with intragastric feeding from Postnatal Days 4 through 17 or 18. In the first study the effects of artificial rearing on male Long-Evans rats were examined. In the second study female Wistar rats were exposed to a single tastant, sucrose, which was introduced on a background of taste deprivation. Results of both studies were similar. No differences in taste sensitivity or preference were detected between animals subjected to taste deprivation or selective taste exposure and their normally reared littermates. These results suggest that suckling stimulation is not necessary for normal taste development and that the taste system of the rat is not particularly susceptible to the influence of early experience. Other interpretations of these results are also discussed.

Bronchodilator effect of the association ipratropium bromide plus fenoterol (low doses) versus terbutaline and salbutamol in bronchitic patients

In 12 chronic bronchitic out-patients, during 3 successive days, the variations of FEV1 and Vmax25 were studied at 15, 30, 45, 60, 120, and 180 min after inhalation of: [0.1 mg fenoterol (F) associated with 0.04 mg ipratropium bromide (IB)]; [0.2 mg salbutamol (S)], and [0.5 mg terbutaline (T)]. There were no secondary effects resulting from any treatment. Maximum effectiveness appeared on FEV1 at 60 min with F + IB, and at 45 min with S and T. On Vmax25, it was produced after 30 min with F + IB and no modifications in this parameter were observed either with S or with T. After 15 min, there were changes on FEV1 with the three products: P less than 0.001 for F + IB and S; p less than 0.01 for T. The variation persisted for up to 120 min with F + IB (p less than 0.001) and with S (p less than 0.05), and for up to 60 min with T (p less than 0.01). With F + IB, Vmax25 increased since after 15 min (p less than 0.001) and up to 60 min (p less than 0.01). In conclusion, the association of a small dose of F to IB provides as positive results as S, and better than T, in a group of chronic bronchitic out-patients.

Resistance to metocurine-induced neuromuscular blockade in patients receiving phenytoin

Recent reports have described resistance to pancuronium-induced neuromuscular blockade in patients chronically receiving anticonvulsants. This study examines the pharmacokinetics and pharmacodynamics of metocurine (MTC) in 12 patients undergoing craniotomy--six on chronic phenytoin therapy and six comparable controls. Each patient received MTC 0.2 mg/kg during the induction of general anesthesia. Quantification of plasma MTC concentration was performed by radioimmunoassay, while the response to MTC was evaluated by evoked compound electromyography (ECEMG). Patients in the phenytoin group were resistant to this dosage of MTC, as demonstrated by their response (83 +/- 16% compared with 98 +/- 2% depression of ECEMG in control patients, P less than 0.05) and by recovery index, defined as the time required for recovery from 25 to 75% of the control ECEMG (53 +/- 22 min compared with 125 +/- 54 min in control patients, P less than 0.01). Similarly, the total duration of neuromuscular blockade, measured to recovery to 90% of control ECEMG, was significantly shorter in the phenytoin group (122 +/- 25 min compared with 269 +/- 64 min in the control group, P less than 0.01). Plasma concentration-time curves were fit to biexponential equations for both groups. These were used to generate two-compartment models. Neither the model parameters nor the plasma concentrations of MTC at any time in the study were significantly different for the two groups. The pharmacodynamic analysis, however, showed that patients on phenytoin require a higher plasma concentration of MTC (0.415 +/- 0.095 microgram/ml compared with 0.249 +/- 0.066 microgram/ml in control patients at 50% ECEMG, P less than 0.01) to effect a given level of neuromuscular blockade.(ABSTRACT TRUNCATED AT 250 WORDS)

Somatostatin analogs: correlation of receptor affinity with inhibition of cyclic AMP formation in pancreatic acinar cells

Somatostatin inhibited secretin-stimulated cyclic AMP formation in pancreatic acinar cells. The inhibition was only partial. Maximal inhibition reached about 50%. Somatostatin analogs tested inhibited secretin-stimulated cyclic AMP formation with a lower potency than somatostatin. Cys-Aza Ala-Phe-Phe-DTrp-Lys-Thr-Phe-Phe-Cys was found to be an antagonist of somatostatin in inhibiting secretin-stimulated cyclic AMP. Analogs inhibited the binding of 125I-[Tyr11] somatostatin to pancreatic acini. There was a good correlation (r = 0.97) between concentration for inhibiting 50% secretin-stimulated cyclic AMP and receptor binding affinities.

Pharmacokinetics and pharmacodynamics of d-tubocurarine and metocurine in the elderly

The effects of age (older than 70 yr) on the pharmacokinetics and pharmacodynamics of d-tubocurarine (dTc) and metocurine (MTc) were evaluated in studies of 21 patients aged 70-87 and 21 patients aged 29-59. There was a significant difference in the pharmacokinetic parameters of all elderly patients compared with younger controls. With both dTc and MTc, the elderly exhibited a decreased plasma clearance, decreased initial volume of distribution, decreased volume of distribution, and a prolonged elimination half-life. After 0.3 mg/kg of dTc, the times for 50% return of twitch and recovery index (25-75% return of twitch response) in the elderly were significantly longer than in the young (P less than 0.02). A similar observation was made for the elderly patients receiving 0.15 mg/kg of MTc. No significant difference was seen in the log plasma concentration-twitch response relationship between 20-80% paralysis in young and in elderly patients receiving dTc. There was a similar lack of significant difference between the log plasma concentration-twitch response lines for elderly and young patients receiving MTc. Because there was no difference between the plasma concentration-response relationships in the elderly and young, altered sensitivity to dTc or MTc cannot explain the longer duration of action seen in the elderly. The most likely explanation for this difference is the altered pharmacokinetics of these two drugs in the elderly.

Intrauterine contraception with copper and with levonorgestrel: a randomized study of the TCu 380Ag and levonorgestrel 20 mcg/day devices

First year results of a randomized study of 1509 users of the Copper T380Ag with a silver core or of an IUD releasing 20 mcg day of levonorgestrel are reported. The cumulative gross pregnancy rate for each device was 0.3 per 100 at one year, with more than 490 women having one year of use with each device. The levonorgestrel-releasing device was associated with significantly fewer bleeding days and significantly increased hemoglobin levels when compared with pre-admission values or the one year values observed among users of the TCu380Ag. Terminations attributable to amenorrhea were significantly more frequent among users of the levonorgestrel-releasing device. The TCu 380Ag was associated with increased frequency and severity of dysmenorrhea compared with pre-admission levels or with the steroid-releasing device. Hemoglobin levels were somewhat reduced among users of the TCu 380Ag device. Terminations attributable to pain were, however, not significantly different by device. Continuation rates at the end of the first year were not significantly different by device.

Distribution, elimination, and action of d-tubocurarine in neonates, infants, children, and adults

The relation of plasma concentration of d-tubocurarine (dTc) to neuromuscular blockade, and the distribution and urinary excretion of dTc was determined in neonates (n = 4), infants (n = 6), children (n = 8), and adults (n = 8). The plasma concentration-time course curves to 24 hr are best described for all groups by three-compartment models. Both neonates and infants exhibit decreased plasma clearance (CLP), 1.1 +/- 0.08 and 1.0 +/- 0.06 ml X kg-1 X min-1, and in addition a prolonged t1/2 terminal phase, 311 +/- 44 and 306 +/- 35 (mean +/- SEM, min). The neonates' 24-hr urinary excretion, 27 +/- 2 (mean +/- SEM, % total dose) is significantly less than the adult value, 45 +/- 4% total dose. There was no significant difference seen in the log plasma concentration-evoked compound electromyogram (ECEMG) response between 20-80% paralysis for adults, children, infants, and five of the seven neonates studied. Two of the neonates had a significant shift of their log concentration-response curve to the right. There was also no significant difference between any of the groups in the time for 50% return of ECEMG stimulus height or the time required for recovery of the ECEMG from 25 to 75% of control value. for recovery of the ECEMG from 25 to 75% of control value.

Somatic and central nervous system growth in artificially reared rat pups

Rearing preweanling rat pups away from their mothers by feeding through chronic intragastric cannulas has been shown to result in alterations in the growth of specific organs. In the present study, artificially reared (AR) rats and their normally reared (NR) siblings were sacrificed at various ages during this procedure to determine the time course of these alterations. Brain growth deficits were detected within 24 hours, peaked after 8 days of artificial rearing and showed some recovery by the end of the study. By day 18, the livers, kidneys and spleens of the AR pups were significantly larger than those of their NR siblings. The spleens showed an initial decrease in weight compared to the spleens of the NR pups. However, by day 18, the spleens of the AR group were significantly larger than those of the NR group.

Disruption of the brain growth spurt in adolescent rats by chronic phenobarbital administration

Postweanling rats received daily injections of either 60 mg/kg phenobarbital, 15 mg/kg phenobarbital, or the drug vehicle from their postnatal days 25 through 39. Even though there were no differences among the groups in body weight, the group receiving 50 mg/kg phenobarbital had significantly smaller whole brain weights and larger liver weights than the other groups. These data suggest that, (i) brain growth may be vulnerable to disruption even in its late stages and (ii) barbiturates may constitute a threat to normal brain growth.

Two years' experience with two levonorgestrel-releasing intrauterine devices and one copper-releasing intrauterine device: a randomized comparative performance study

A randomized comparative performance study of two levonorgestrel intrauterine devices (IUDs) and a copper (Nova-T) IUD (Leiras, Turku, Finland) was performed at two clinics in Finland and one in Brazil. The 24-month cumulative event rates per 100 women are reported. Six thousand woman-months of use were recorded with the levonorgestrel IUD and 3000 with the Nova-T device. Pregnancy rates at 2 years of use were 0.6 and 0 with the two levonorgestrel IUDs and 3.3 with the Nova-T IUD. Removal rates because of bleeding and/or pain were low with all three IUDs: 7.5, 7.6, and 7.1, respectively, at 24 months. Recordings of the number of days of bleeding showed significantly fewer days of bleeding during use of the levonorgestrel IUDs than the Nova-T IUD from the second month of use onward, until the end of the second year. No infections were recorded in association with use of the levonorgestrel IUDs, and only one termination because of infection was recorded for the Nova-T IUD. The continuation rates of use at 24 months were 66.6, 60.7, and 71.9 for the two levonorgestrel IUDs and the Nova-T IUD, respectively; the differences were not statistically significant.

A microwave-hyperthermia model of febrile convulsions

While convulsions associated with fever represent a serious problem in pediatric medicine, conventional animal models of febrile convulsions suffer numerous technical limitations. A microwave-hyperthermia model that eliminates these problems was tested. Microwave energy was used to increase the core temperature of 13- and 17-day-old rats, resulting in convulsions similar to febrile convulsions in human infants. Rats were irradiated for 10 min in circularly polarized waveguides at 918 MHz, CW (average SAR = 9.4 W/kg at 13 days and 18.0 W/kg at 17 days as determined by twin-well calorimetry). Day 17 irradiated rats were less susceptible to convulsions that were day 13 irradiated rats, indicating an age-dependent decline in susceptibility. Contrary to findings of earlier models using infrared or hot-oven heating, convulsions induced with microwave hyperthermia impaired neither brain growth nor subsequent performance during behavioral testing. Simultaneous measurement of brain and rectal temperatures during microwave irradiation revealed differential heating rates that favor thermal homeostasis in brain tissue.

Infant gastrostomy and chronic formula infusion as a technique to overfeed and accelerate weight gain of neonatal rats

Female rat pups were overfed by continuous intragastric infusion of a milk formula from day 4 through day 128 postpartum. These rats dramatically accelerated weight gain after day 109. By day 18 the overfed pups weighted significantly more than both normally reared 18-day-old pups and pups reared artificially but maintained at the same growth rate as normally reared pups. On day 18 the catheters were removed from gastrostomized pups and normally reared pups were removed from their dams. Thereafter, all groups were maintained ad libitum on a standard diet. The body weights of overfed pups were still significantly greater than those of both other groups on day 120. The procedure provides an important new tool to examine the role of early nutrition in the etiology of obesity.

Artificial rearing of rat pups with a protein-enriched formula

Neonatal Long-Evans hooded rat pups were assigned to one of three groups: 1) pups normally reared, 2) pups implanted with intragastric cannulas and artificially reared with a common milk replacement formula, 3) pups implanted with intragastric cannulas and artificially reared with a protein-enriched milk formula. Daily body weights were recorded, as were the ontogeny of various reflexes. On day 18, the animals were behaviorally tested and then killed. There were no differences among the three groups in daily body weights, nor in the ontogeny of reflexive behavior. There were no differences in the wet weights of caudal brain sections, but the normally reared animals had significantly larger rostral brain sections than either artificially reared group. While cerebella of normally reared animals were significantly larger than those of the two artificially reared groups, there was a significant trend towards more normal cerebellar weights with the addition of protein in the formula of artificially reared animals. Behavioral tests indicated that the animals artificially reared have significantly different behavior than normally reared animals. However, compared to animals artificially reared using a common milk formula, animals artificially reared with additional protein in their formula behave more like normally reared animals.

Clinical performance of a new levonorgestrel-releasing intrauterine device. A randomized comparison with a nova-T-copper device

The clinical performance of two levonorgestrel-releasing intrauterine devices (IUDs) with different release rates was studied and compared with a copper-releasing Nova-T device in a randomized partly double-blind multiclinical trial. Special attention was given to patterns of bleeding, hormonal side-effects, blood pressure and body weight. The clinical acceptability of the levonorgestrel IUDs was as good as that of the copper-releasing IUD. A highly significant decrease in the amount of menstrual blood loss was seen with the levonorgestrel-IUDs, the users of which experienced fewer days of bleeding than prior to insertion. Patients suffering from dysmenorrhea experienced relief from this symptom after insertion of a levonorgestrel-IUD. Some side-effects, usually referred to as hormonal, increased during the levonorgestrel-IUD use, but did not result in higher termination rates than with the Nova-T device. No changes in body weight were recorded for the levonorgestrel-IUDs and a slight decrease in both systolic and diastolic blood pressure was found after one year of use. No infections were recorded.

Association of marital status and years of schooling with perinatal outcome: the influence of pre-natal care as an intermediate variable

The association between mother's education and perinatal mortality, and between marital status and proportion of preterm deliveries was analyzed using data from 20,000 women and newborns delivered at the Hospital Barros Luco-Trudeau in Santiago, Chile. A highly significant correlation was found, but after being controlled by pre-natal care, that association disappeared for those mothers with good pre-natal care, remaining only as a part of the association for women who did not attend the pre-natal clinics or did not follow minimal standards of care. The definition used for "good pre-natal care" was much less demanding than WHO recommendation. We required a minimum of only 5 visits, starting before the 5th month of the pregnancy and with blood pressure and body weight registered at each visit. Pre-natal assistance was provided mostly by registered midwives, with occasional consultation by physicians. The efficiency of a low cost health activity, such as pre-natal care, in improving infant health is held in contrast with the inefficiency of high cost technology when applied to developing countries' health problems.

Effects of dipropylacetate on brain development

Dipropylacetate (DPA: valproic acid) is a new anticonvulsant reported to be effective in many types of seizures including those that occur early in life. This study describes the effects of chronic administration of DPA upon a developing organism. Four-day-old rat pups were injected daily with either 75 mg/kg DPA, 200 mg/kg DPA, or vehicle until day 18. Administration of DPA resulted in decreased body and organ weights, with the greatest reductions in the 200 mg/kg group. To control caloric intake, and additional experiment was conducted. Animals were injected with either vehicle or 200 mg/kg DPA. Each animal was implanted with a chronic intragastric cannula and fed through the cannula. The results of this experiment indicated that body and organ weights were the same for both vehicle and drug groups, except for brain. The animals receiving DPA had significant deficits of 12% in total brain weight and 22% in weight of the cerebellum. The data suggest that chronic administration of DPA early in life may have adverse consequences on brain growth.

A multicenter study of levonorgestrel-estradiol contraceptive vaginal rings. II-Subjective and objective measures of effects. An international comparative trial

Comparative clinical trials of 2 sizes of contraceptive vaginal rings and of an oral contraceptive were undertaken at 8 investigational sites (9 clinics). More than 500 women enrolled on each of the 3 study regimens. Side effects of the rings and of Nordette, the oral contraceptive, were evaluated by noting spontaneous complaints, by recording medications taken and by physical examination. Inquiries about changes in the frequency of specific conditions were made at the end of the subjects participation in the first year of the study. The incidence of spontaneous complaints was similar among users of the 2 different-sized rings and of the pill.

A multicenter study of levonorgestrel-estradiol contraceptive vaginal rings. III-Menstrual patterns. An international comparative trial

Menstrual events among users of contraceptive vaginal rings (CVRs), releasing levonorgestrel and estradiol, were studied in comparison with a combined oral contraceptive, Nordette, in multicentered trials. CVRs were made with outside diameters of 50 and 58 mm and released about 250 micrograms and 290 microgram of levonorgestrel and 150 microgram and 180 microgram of estradiol per day, respectively. The CVRs were used continuously for 3 weeks and then removed for 1 week. Both the CVRs and Nordette were perceived to reduce menstrual flow and days of menstrual bleeding. Twenty to 25% of CVR users perceived increased intermenstrual bleeding or spotting. Diaries indicate, however, that on average, CVR users experienced about 1 day per month of bleeding or spotting with the ring in place. CVRs and Nordette produced approximately the same total number of bleeding and spotting days during 6 cycles of use, 27-29, but the small (50-mm OD) ring was associated with somewhat more spotting. This ring was also associated with somewhat more prolonged bleeding and spotting runs and with more prolonged nonbleeding intervals than reported by users of the larger (58-mm OD) ring or of Nordette. Differences among regimens, however, tended to be small even when statistically significant. Evidence from menstrual diaries indicates that these CVRs, and in particular 58-mm ring, provide control over the menstrual cycle comparable to the Nordette.

Altered development of brain by neonatal ethanol exposure: zinc levels during and after exposure

Neonatal rats, exposed to ethanol by use of an artificial rearing technique during the first postnatal week, have been shown to have a 20% reduction in brain weight compared to littermate controls. The mechanisms responsible for this deficit remain to be determined. One hypothesis, which has been suggested that could be responsible for the microcephaly observed in the Fetal Alcohol Syndrome is that human alcoholics have decreased serum zinc levels. It is well documented that zinc deficiency in rats results in microcephaly. Thus, ethanol administered in the diet could result in lowered zinc levels in serum and brain, and hence be the underlying factor for the brain growth deficiency reported. In these studies, serum and brain zinc levels were determined for animals exposed to ethanol using the artificial rearing procedure, and for their littermate controls, artificially reared on the same formula without ethanol. No differences at any time were found in either serum or brain zinc levels. This would suggest that zinc availability could not account for the effects found on brain growth.

Intrauterine contraception with levonorgestrel: a comparative randomised clinical performance study

Two levonorgestrel-releasing intrauterine devices (IUD) with different release rates of levonorgestrel and a 'Nova-T' copper-releasing device were compared in a randomised clinical performance study. 327 women had a levonorgestrel IUD and 156 women a nova-T device inserted postmenstrually. No statistically significant differences in the reasons for termination between the three devices were found in 12 months. The continuation rates for the two levonorgestrel IUDs were 84.1 and 81.4 and for the nova-T device 87.5. Duration of menstrual bleeding and spotting was highly significantly shorter with the levonorgestrel IUDs than with the nova-T device. There were no infections.

Impaired brain growth in neonatal rats exposed to ethanol

Infant rat pups, fed through intragastric cannulas from postnatal day 4 through day 18, showed a 19 percent reduction in total brain weight when ethanol was included in their diet on days 4 through 7. This reduction in brain weight occurred even though body growth in the experimental rats was equal to that of their littermate controls. The ethanol-exposed animals were markedly hypoactive during the period of drug administration, then displayed gross body tremors for 3 to 5 days. Throughout the study, the animals treated with ethanol had poor motor coordination and were hyperresponsive. These brain and behavioral effects appear similar to those seen in fetal alcohol syndrome.

Clinical trial with subdermal implants containing norgestrienone

Norgestrienone implants delivering approximately 225 microgram/ day were tested clinically for contraceptive effectiveness and acceptability in 145 women. Five pregnancies occurred in 2259 woman-months of use, one in the 11th month, one in the 15th and three in the 16th month of use. Continuation rate at 12 months was 86.7. The number of bleeding runs and bleeding days was increased in approximately 12% of the subjects. Ten percent of the patients had no bleeding in the first 90 days of treatment. Changes in bleeding pattern led to closures in four cases. Headache and signs of mild androgenicity were among the leading side effects. Blood and urine analysis throughout the study showed normal values of 17 different parameters, but a tendency to lower cholesterolemia not associated with changes in thyroid hormone levels, was observed in several patients. Cortisol was found slightly under the lower normal range in one subject without clinical manifestations of hypoadrenalism. It is concluded that norgestrienone implants should be replaced every twelve months for maximal contraceptive effect and because of their efficacy and good acceptability, evaluation of their long term use is warranted.