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Biomedical subjects

M Rush

Publications and source records attributed to M Rush.

At least 37 records · Page 2Linked to original sources
PubMed1987

Isolated gonadotropin-releasing hormone neurons harvested from adult male rats secrete biologically active neuropeptide in a regular repetitive manner.

Immunochemical treatments for the recovery of viable GnRH neurons from adult male rats have previously been described by this laboratory. In the present report, efforts were made to limit cellular adhesion, as well as the proteolytic and mechanical damage which occurred during isolation of the neurons, in order to determine if such damage may account for failure of the isolated cells to exhibit spontaneous neuropeptide release. These modifications prevented the loss of assayable GnRH during the isolation process, and neurons recovered from individual rats in this study contained 10.7 +/- 2.5 ng GnRH. Further, all isolated neuronal preparations exhibited spontaneous peptide release which continued in a regular repetitive manner. When maintained in closed chambers, these preparations released 105 +/- 42 pg/ml biologically active GnRH at 18.9 +/- 0.4-min intervals. In contrast, GnRH release from heterologous preparations was characterized by erratic low level pulses. The results from this work suggest that independent neuroendocrine properties of GnRH neurons may be responsible for tonic gonadotropin secretion in castrated adult male rats and that the erratic patterns of gonadotropin release in gonadally intact males may be related, in part, to coupling between GnRH neurons and unidentified neuronal factors.

Animals↗
PubMed1986

Osteoblastic insufficiency is responsible for maintenance of osteopenia after loss of ovarian function in experimental beagle dogs.

Bone loss developing after cessation of ovarian function in humans represents a major health problem. To establish the value of ovariohysterectomy in female beagle dogs as a model for bone loss and to study static and dynamic parameters of bone associated with the negative bone balance occurring after cessation of ovarian function, we performed iliac crest bone biopsies before and 4 months after ovariohysterectomy in eight beagle dogs and in five sham-operated controls. Cessation of ovarian function was documented by an increase in serum levels of LH 4 weeks after ovariohysterectomy. There was no change in serum calcium, phosphorus, and creatinine during the 4 months of the study. Cancellous bone mass and trabecular mean wall thickness decreased significantly after ovariohysterectomy (P less than 0.01). In addition, the number of osteoblasts was increased and the bone formation rate per osteoblast, that is, the activity of bone-forming cells, was decreased (P less than 0.01). Parameters of bone resorption were not significantly altered in the animals with ovariohysterectomy. No changes in histomorphometric parameters of bone structure, formation or resorption were observed in the sham-operated controls. These data indicate that ovariohysterectomy in beagle dogs may serve as a useful model for bone loss associated with cessation of ovarian function. Osteoblastic insufficiency appears to play a major role in the maintenance of bone loss occurring after ovariohysterectomy in beagle dogs.

Amenorrhea↗
PubMed1985

Duplex scanning with continuous wave Doppler for carotid disease.

Duplex scanning with the use of continuous wave Doppler instrumentation was used for the evaluation of carotid disease and compared to angiography. In twenty such patients 100% accuracy for diagnosis of total occlusion by Duplex scanning with continuous wave Doppler, was obtained. The sensitivity for those patients with 50%-99% stenosis was 92% and for those patients with 20%-49% stenosis was 75%. The overall accuracy for this diagnostic test for all groups of stenosis was 85%. This compares favorably with other noninvasive vascular techniques and is felt to be an accurate and useful technique for the detection of carotid stenosis. Several advantages of this technique are pointed out.

Angiography↗
PubMed1984

Recurrent carotid artery stenosis following endarterectomy.

Spectral analysis was used to examine 257 carotid arteries in 227 patients who had undergone carotid endarterectomy at 1, 3, 6, and 12 months after surgery and annually thereafter. Routine intraoperative completion angiography ensured that the operations were technically satisfactory. Postoperative restenoses were identified in 38 patients (15%). In 23 arteries (9%), the restenosis exceeded a 50% diameter reduction while in 15 arteries (6%) the stenosis was less than 50% of the diameter. Restenosis developed in 24/96 women (25%) and 14/161 men (9%). Twenty-nine (70%) stenotic lesions occurred within 12 months. In three patients early lesions regressed. Reoperation with patch angio-plasty was required in six patients. When the 219 carotid arteries that remained widely patent were compared to the 38 that restenosed , no differences were noted for age, diabetes mellitus, hypertension, smoking, or degree of preoperative stenosis. Early stenotic lesions appear to be due to myointimal hyperplasia, which is probably platelet mediated. The predominant female sex distribution may be explained by differences in platelet responsiveness in men and women.

Arterial Occlusive Diseases↗
PubMed1984

A calcified adenocarcinoma of the lung with very high CT numbers.

A case is reported of a man with a solitary pulmonary nodule that had an average CT number of 366 HU. Biopsy of the lesion demonstrated a primary adenocarcinoma of the lung with diffuse calcification. It is concluded that high CT numbers of solitary nodules do not ensure a benign lesion.

Adenocarcinoma↗
PubMed1984

Carotid steal syndrome following carotid subclavian bypass.

Subclavian steal syndrome may result from stenosis or occlusion of the subclavian artery proximal to the origin of the vertebral artery. The diagnosis can be confirmed by noninvasive vascular studies with the use of a directional Doppler probe or by time-sequence aortic arch angiography, both of which can detect retrograde flow in the vertebral artery. A variety of surgical approaches to this condition have been used in the past, but the simpler and much safer carotid-to-subclavian bypass has become a more acceptable surgical procedure. There remains, however, a theoretical possibility that blood may be siphoned from the intracranial arteries perfused by the carotid. This phenomenon, which may be called the carotid steal syndrome, has been discussed, but no clinical cases have been reported. We present a patient who developed such a carotid steal syndrome 2 years after left carotid-subclavian bypass. This occurrence reemphasizes the importance of determining a normal carotid bifurcation prior to performing carotid-subclavian bypass.

Arterial Occlusive Diseases↗
PubMed1981

Lightning risk.

Since 1969, ninety-four persons were reportedly killed annually by lightning in the United States. Reported injuries were almost three times the fatalities. These casualties were not evenly distributed across the country. The purpose of this paper was to examine the expected distribution of these occurrences using known ecologic risk factors. Lightning fatalities and injuries were related to thunderstorm days, population characteristics, and land area. The resulting predicted casualties were mapped and indicate where preventive measures are needed. This same technique could be employed to examine most natural hazard risks using existing data.

Humans↗
PubMed1975

Detection and quantitation of Staphylococcus aureus penicillinase plasmid deoxyribonucleic acid by reassociation kinetics.

The quantity of penicillinase plasmid deoxyribonucleic acid (DNA) in various strains of Staphylococcus aureus has been determined by DNA-DNA reassociation kinetics. Specifically, 32P- or 125I-labeled denatured probes of purified plasmid DNA were reassociated in the presence of denatured DNAs isolated from the bacterial strains in question. The number of plasmid copies per cell was calculated from the effect of the latter nucleic acid samples on the reassociation rate of the radiolabeled probe. Among the S. aureus strains examined were monoplasmid, diplasmid and replication-defective representatives, and the effect of temperature on wild-type plasmid content was also investigated.

Base Sequence↗
PubMed1975

Nucleic acid hybridization analysis of an integrated plasmid in Staphylococcus aureus.

A series of studies were performed on a Staphylococcus aureus strain thought to contain a pencillinase plasmid integrated into the host chromosome. Reassociation kinetics analysis of whole-cell deoxyribonucleic acid (DNA) in the presence of pure radioactive plasmid DNA revealed that plasmid-specific sequences were present at about 1 copy per chromosome equivalent as compared to 3.6 copies for the same plasmid in its autonomous state. Consistent with this observation was the finding that penicillinase activity was lower for the former strain than for the latter. It was shown further that the plasmid-specific sequences cosedimented on neutral sucrose gradients with fragments of whole-cell DNA many times larger than the plasmid. These two findings were taken as strongly confirmatory of the integrated state. Analysis of whole-cell ribonucleic acid for the presence of plasmid-specific messengers revealed that these were present in approximately the amounts expected on the basis of the DNA study.

Base Sequence↗