Effect of maternal age on autosomal trisomies

The effect of maternal age on the genesis of trisomy was studied by comparing data from 362 trisomic and 790 chromosomally normal spontaneous abortions. As a group the trisomies were associated with a substantial increase in maternal age but there were considerable differences in the magnitude of the effect for different trisomies. The effect of increasing maternal age was most pronounced for trisomies involving the small chromosomes, both acrocentric and non-acrocentric. However, trisomy 16 was conspicuously different from trisomies for all the other small chromosomes, both in the reduced importance of increased maternal age and in the high frequency with which it occurred. The effect of increasing maternal age on trisomies for chromosomes in groups A, B and C was less clear than that for the small chromosomes. However, the evidence suggested that trisomy for these chromosomes was associated with a moderate increase in maternal age.
It was suggested that the maternal age-dependent trisomies might result from precocious disjunction of the bivalents and random segregation of the resulting univalents, a process which would affect chromosomes with the fewest number of chiasmata and which might be more prevalent in oocytes of older women. It was further suggested that true non-disjunction, that is, the failure of bivalents to separate at anaphase, might also result in the production of trisomies. This process might be independent of, or only slightly influenced by, increasing maternal age but be affected by the presence of large blocks of heterochromatin.     

Acute, Pharmacokinetic, and Subchronic Toxicological Sudies of 2,4-Dichlorophenoxyacetic Acid

The single-dose oral LD₅₀ values in Fischer 344 rats for technical-grade2,4-dichlorophenoxyacetic acid (2,4-D), es ters, and salts rangedfrom 553 mg/kg (isobutyl ester in females) to 1090 mg/kg (dimethylaminesalt in males). The LDH values for the acid, esters, or salts,when expressed as acid equivalents, were consistent which suggeststhat the acute toxicity was due to 2,4-D per se. Acute dermalLD₅₀ values in rabbits for the acid, esters, and salts weregreater than 2000 mg/kg. Overall, these results indicate thatthe acute oral and dermal toxicity of 2,4-D are low. Pharmacokineticswere evaluated in male Fischer 344 rats given single oral dosesof 10, 25, 50, 100, or ISO mg 2,4- [¹⁴CJD/kg The amount of 2,4-Din the plasma, kidney, and urine 6 hr postdosing indicated thatthe urinary elimination of 2,4-D was saturated in male ratsgiven oral doses in excess of 50 mg/ kg. Subchronic dietarystudies in male and female Fischer 344 rats used dose levelsof 0, 15, 60, 100, or 150 mg/kg/thy of purified or technical-grade2,4-D acid for 13 weeks. Body weight gains were decreased forboth sexes at the higher dose levels of purified and technical-grade2,4-D acid. Kidney weights were increased in all treated malerats and in females given the higher three dose levels of purified2,4-D. Treatment-related cytoplasmic alterations were presentin the renal proximal tubules of most rats given 60mg/kg/thyand higher of purified or technical-grade 2,4- D; a few femalesgiven 15 mg/kg/thy also had slight alterations in the cytoplasmof the proximal tubules. A dose-related degenerative changewas identified in the descending proximal renal tubules of allmale rats given the highest three dose levels of either testmaterial and some given 15 mg/kg/thy. Dose levels of 100 or150 mg/kg/thy of either compound for both sexes produced minimalswelling and increased staining homogeneity in the liver cellsand were associated with a slight elevation of liver weightand serum glutamic pyruvic transaminase activity. Higher doselevels of technical-grade and purified 2,4-D decreased totalserum tetraiodothyronine levels in female rats, however, themorphology of the thyroid gland was normal. The no-observed-effectlevel (NOEL) was less than 15 mg/kg/day for both purified andtechnical-grade 2,4-D acid.     

Glucagon releasing activity of a cyclic peptide related to somatostatin

A possible benefit of creating smaller and more rigid active analogs of somatostatin is the discovery of compounds which selectively inhibit the secretion of insulin, glucagon or growth hormone. A series of cyclic tetrapeptide analogs related to somatostatin was synthesized, and one member of this series was found to cause an unexpected stimulation of glucagon secretion while having little if any effect on either insulin or growth hormone secretion. A sustained increase in plasma glucose levels was also observed. Two possible modes of action are proposed.     

Clinical Features of Multiple Glomus Tumors

BACKGROUND While glomus tumors are usually solitary, multiple glomus tumors do occur. The purpose of this study was to review the clinical characteristics and outcomes in a series of patients with multiple glomus tumors presenting to our institution.
METHODS A retrospective review of patients with multiple glomus tumors seen at our institution over the past 25 years was performed.
RESULTS Twenty-two patients with multiple glomus tumors were identified. Initial diagnosis was blue rubber nevus syndrome and hemangioma in 10 and 7 patients, respectively. The mean duration from onset of symptoms until correct diagnosis was 14.6 years. Involvement of an extremity was noted in 90.9% of the patients. An autosomal dominant pattern of inheritance was noted in 13 of 22 patients. The classic triad of symptoms in solitary glomus tumors—pain, pinpoint tenderness, and cold hypersensitivity—was noted in only 1 of the 22 patients; pain and pinpoint tenderness were simultaneously identified in 14 patients, 8 with visible lesions but no symptoms. Symptoms were relieved by surgical excision in most patients.
CONCLUSION Patients with multiple glomus tumors are frequently misdiagnosed. Proper recognition and diagnosis would lead to improved management.     

The Implantable Neurocybernetic Prosthesis System

The neurocybernetic prosthesis system (NCP) is an implantable, multiprogrammable pulse generator that delivers constant current electrical signals to the vagus nerve for the purpose of reducing the frequency and severity of epileptic seizures. The signals are delivered on a predetermined schedule, or may be initiated by the patient with an external magnet. The device is implanted in a subcutaneous pocket in the chest just below the clavicle, similar to pacemaker placement. The stimulation signal is transmitted from the prosthesis to the vagus nerve through a lead connected to an electrode which is a multi-turn silicone helix, with a platinum band on the inner turn of one helix. The prosthesis can be programmed with any IBM- compatible personal computer using NCP software and a programming wand.