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Biomedical subjects

D Silverstein

Publications and source records attributed to D Silverstein.

At least 19 recordsLinked to original sources
PubMed1996

Characterization of a new Marburg virus isolated from a 1987 fatal case in Kenya.

In 1987, an isolated case of fatal Marburg disease was recognized during routine clinical haemorrhagic fever virus surveillance conducted in Kenya. This report describes the isolation and partial characterization of the new Marburg virus (strain Ravn) isolated from this case. The Ravn isolate was indistinguishable from reference Marburg virus strains by cross-neutralization testing. Virus particles and aggregates of Marburg nucleocapsid matrix in Ravn-infected vero cells, were visualized by immunoelectron microscopic techniques, and also in tissues obtained from the patient and from inoculated monkeys. The cell culture isolate produced a haemorrhagic disease typical of Marburg virus infection when inoculated into rhesus monkeys. Disease was characterized by the sudden appearance of fever and anorexia within 4 to 7 days, and death by day 11. Comparison of nucleotide sequences for portions of the glycoprotein genes of Marburg-Ravn were compared with Marburg reference strains Musoki (MUS) and Popp (POP). Nucleotide identity in this alignment between RAV and MUS is 72.3%, RAV and POP is 71%, and MUS and POP is 91.7%. Amino acid identity between RAV and MUS is 72%, RAV and POP is 67%, and MUS and POP is 93%. These data suggest that Ravn is another subtype of Marburg virus, analogous to the emerging picture of a spectrum of Ebola geographic isolates and subtypes.

Adolescent↗
PubMed1996

Mechanism of renal phosphate retention during growth.

We have previously demonstrated that the retention of phosphate required for growth is due to a a high Vmax of the Na(+)-Pi cotransport system located in the brush border membrane of the proximal tubule. Because of this and other similarities between adaptation of the kidney to a high Pi demand (growth) and that to low Pi supply, we measured the levels of NaPi-2 mRNA and cDNA present in kidney cortex of 3- and > 12-week-old rats. Like in Pi depletion, Western blots revealed that a 80 to 85 kDa protein recognized by a polyclonal antibody directed against the N-terminal region of the NaPi-2 protein was 2.3-fold more abundant in renal microvilli of the young than of adult animals. However, unlike in Pi depletion, Northern blot analysis failed to reveal a significant difference between mRNA levels at the two ages. Furthermore, suppression of NaPi-2 mRNA activity by annealing with antisense oligomers, or removal of the NaPi-2 transcripts by subtractive hybridization did not affect the rate of Na(+)-Pi cotransport induced in oocytes by polyA RNA of rapidly growing animals, while abolishing the ability of the renal cortical polyA RNA of adult rats to encode for Na(+)-Pi cotransport. RT-PCR of subtracted polyA RNA using primers specific for a region conserved in NaPi type II (Pi modulated) cotransporters yielded a product that was 98% homologous with that region, despite the absence of NaPi-2 cDNA. The results of these experiments demonstrate that the polyA RNA from kidneys of young animals contains unique mRNA transcripts able to encode for a NaPi protein homologous to, but distinct from NaPi-2.

Age Factors↗
PubMed1992

Inflammation on the cervical Papanicolaou smear: the predictive value for infection in asymptomatic women.

BACKGROUND: The clinical significance of inflammation on the cervical Papanicolaou (Pap) smear of asymptomatic women is unknown. This study assessed the possible association between inflammation on Pap smears with the presence of cervical/vaginal pathogens. METHODS: A questionnaire was given to 290 asymptomatic women seen for routine gynecologic examination, including Pap smear, in a primary care setting. The women were tested for the presence of Candida species, Trichomonas vaginalis, Gardnerella vaginalis, Neisseria gonnorrhoeae, and Chlamydia trachomatis. RESULTS: Recovery of Chlamydia and Trichomonas was more frequent in women with inflammation on Pap smear than in women without inflammation, but the positive predictive value of inflammation was only 7% for Chlamydia and 14% for Trichomonas. Seventy-one percent of the women with inflammation had no evidence of any of the organisms. After a 6-month follow-up period, women with inflammation on Pap smear were no more likely than their matched counterparts without inflammation to return for a clinic visit with symptoms of vaginitis. CONCLUSIONS: In this study, inflammation on Pap smear had a relatively low predictive value for the presence of vaginal pathogens in asymptomatic women.

Adult↗
PubMed1986

Effects of thioglucoses on sensitivity to insulin hypoglycemic convulsions.

Based on the effects of gold thioglucose (GTG), we have previously proposed a regulatory center in brain which adjusts the convulsive response to insulin hypoglycemia. The sensitivity to insulin hypoglycemic convulsions is decreased 24 hr and increased 1 week after a single i.p. injection of GTG. The differences are in the brain's convulsive response to equal hypoglycemia, as the blood glucose response to insulin is unchanged. The generalized convulsive threshold, reflected in the sensitivity to nonmetabolic pentylenetetrazol (Metrazol) convulsions, is not altered. Despite its systemic administration, GTG causes lesions focused in the ventromedial hypothalamus. In the present study, this regulatory center was explored further by the ability of two thioglucoses to substitute for GTG. beta-D-Thioglucose had no effect. 5-Thioglucose simulated the early (24 hr) action of GTG but had no effect at 1 week. However, unlike GTG, 5-thioglucose did not cause the ventromedial hypothalamus lesion. The early (24 hr) and late (1 week) components are thus dissociated. The early effect on insulin hypoglycemic convulsions does not require a ventromedial hypothalamus lesion. Structure-activity relationships and relationships to glucoregulatory systems are discussed.

Animals↗
PubMed1985

Micropuncture of the tympanic membrane after tympanoplasty.

Shortly after tympanoplasty the cause of conductive hearing loss may be difficult to ascertain. If the cause is related to poor eustachian tube function, early aeration of the middle ear should produce an immediate improvement in hearing. A procedure for aerating the middle ear consists of introducing 0.5 cc of air through the graft with a tuberculin syringe and an angled 1.25-inch, 27-gauge needle. Between 1978 and 1983, 75 patients, or 19% of those having tympanoplasties or mastoid tympanoplasties, underwent the micropuncture procedure. Forty-five patients had a hearing improvement after the procedure and there were no complications. It appears that micropuncture of the tympanic membrane is an easily performed, relatively painless, safe procedure after tympanoplasty. It is a useful diagnostic procedure that may also improve the ultimate results of tympanoplasty surgery.

Air↗
PubMed1984

Abnormal left ventricular filling: an early finding in mild to moderate systemic hypertension.

This study was undertaken to determine the prevalence and significance of diastolic left ventricular (LV) dysfunction in mild to moderate systemic hypertension. Rest and exercise equilibrium blood pool scintigraphy was performed in 39 hypertensive subjects (mean systolic blood pressure [BP] 156 +/- 14 mm Hg [+/- standard deviation]; mean diastolic BP 103 +/- 5 mm Hg) and 11 normal control subjects. These studies were analyzed for ejection fraction (EF), segmental wall motion, peak filling rate (PFR), time to PFR and filling fraction in the first third of diastole normalized for cycle length (first-third filling fraction). EF at rest was similar in the hypertensive patients and control subjects (0.63 +/- 0.09 versus 0.65 +/- 0.07); only 2 patients had a reduced EF. The EF response to exercise was normal in every hypertensive patient (increasing to a mean of 0.74 +/- 0.08); only 1 patient had asynergy. In contrast, even when the 2 patients with abnormal systolic function were excluded, each index of diastolic filling was significantly different from the control group. PFR was lower (2.29 +/- 0.49 vs 2.63 +/- 0.39 end-diastolic volumes per second [EDV/s], p less than 0.05), time to PFR was longer (199 +/- 47 versus 158 +/- 17 ms/s), p less than 0.01) and first-third filling fraction was smaller (0.38 +/- 0.11 vs 0.60 +/- 0.07, p less than 0.001). The latter index fell below the lowest normal value in 84% of the hypertensive patients. The degree of diastolic filling abnormality was not related to the patients' age, heart rate, BP, duration of systemic hypertension or systolic function.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Analysis of surgical procedures in patients with vertigo.

The majority of patients with vertigo secondary to inner ear problems can be cured by surgery (80%). The results after neurectomy procedures such as cochleovestibular neurectomy or vestibular neurectomy appear to be much better (85%) than after the endolymphatic subarachnoid shunt procedure (70%). If hearing is worth saving, a conservative procedure should be used first in an effort to preserve the patient's hearing. If this fails, a cochleovestibular neurectomy will usually resolve the problem. At present we are using the retrolabyrinthine vestibular neurectomy as a primary procedure for Meniere's disease, reserving the cochleovestibular neurectomy for those in whom the vestibular neurectomy failed. In elderly patients it appears the Schuknecht cochleosacculotomy may have promise as a first procedure for control of vertigo.

Aged↗
PubMed1984

Use of streptomycin sulfate in the treatment of Meniere's disease.

Streptomycin sulfate has been known to be ototoxic since its use in the treatment of tuberculosis. This report describes 10 years of experience in the treatment of Meniere's disease with streptomycin. Streptomycin has been used in classical Schuknecht ablation of the vestibular system in bilateral Meniere's disease; classical Schuknecht ablation of the vestibular system in unilateral Meniere's disease in the only hearing ear; intratympanic streptomycin in the treatment of unilateral Meniere's disease; and low-dose intramuscular streptomycin as outpatient treatment in unilateral Meniere's disease. The results of bilateral vestibular ablation were similar to Schuknecht's and others. Patients developed profound ataxia with a wide-based gait and oscillopsia, which improved rapidly over a period of months. Approximately 30% experienced significant improvement in hearing, which usually deteriorated again after several months. All patients were relieved of vertigo. Patients with unilateral Meniere's disease in the only hearing ear responded as did the bilateral cases. Hearing in the only hearing ear was preserved in all cases. Low-dose subototoxic streptomycin as outpatient treatment offers promise in some cases for relieving attacks of Meniere's disease while improving hearing without producing the temporary disabling effects of ataxia and oscillopsia. Streptomycin and similar drugs that may reduce the production of endolymph may eventually be the treatment of choice in Meniere's disease.

Ataxia↗
PubMed1983

Right ventricular failure in a patient with diabetic neuropathy (myopathy) and central alveolar hypoventilation.

An unusual patient with hypoxemia, hypercapnia, and right ventricular failure is presented. Minimal skeletal muscle weakness, although present, cannot explain hypercapnia. Muscle biopsy revealed diabetic microangiopathy. Carbon dioxide stimulation demonstrated a diminished hypercapnic ventilatory response. The patient benefited from progesterone therapy. In this unusual patient, mild muscular weakness, caused by diabetes, and central alveolar hypoventilation have acted in synergism to cause abnormal ventilation and right ventricular failure.

Diabetic Neuropathies↗
PubMed1982

Acquired inflammatory superior oblique tendon sheath syndrome. A clinicopathologic study.

To our knowledge, this is the first reported clinicopathologic study of a patient with acquired inflammatory Brown's syndrome. The superior oblique tendon, trochlea, and anterior superior oblique muscle were surgically removed en bloc and studied by light microscopy. Surprisingly, the entire specimen was normal, without signs of inflammation or intrasheath scarring. The only abnormal finding was found during surgery, which consisted of perisheath adhesions anterior to the trochlea. These findings indicate that the cause of acquired inflammatory Brown's syndrome may, in many cases, be from scarring around the tendon sheath rather than an intrasheath pathologic condition, as proposed by recent literature.

Female↗
PubMed1979

Relationship of static respiratory muscle pressure and maximum voluntary ventilation in normal subjects.

40 normal subjects performed spirometry, maximum voluntary ventilation (MVV), and tests of static inspiratory (Pi max) and expiratory (Pe max) respiratory muscle pressure. Forced expiratory volumes in 0.5 (FEV0.5), in 0.75 (FEV0.75), and 1 sec (FEV1) correlated significantly with MVV (r = 0.805, 0.804, 0.779, respectively). When Pi max was considered as a second independent variable, the probability of predicting MVV from timed forced expiratory volumes was enhanced (r = 0.914, 0.900 and 0.872 for FEV0.5, FEV0.75, and FEV1, respectively). Statistical analysis indicated that multiple regression with Pi max was superior to regression with timed forced expiratory volume alone in the prediction of MVV. For any given FEV1, however, Pi max was widely dispersed (range: -60 to -200 cm H2O). MVV values, expressed as percentage difference between largest and smallest value, varied less than did Pi max. Pe max, vital capacity, height and age did not enhance the ability of timed forced expiratory volumes to predict MVV. These data indicate that while respiratory muscle strength is important for sustaining maximal ventilation, the MVV is not a sensitive indicator of respiratory muscle strength.

Adult↗
PubMed1975

Altered control of skin blood flow at high skin and core temperatures.

Five subjects were studied during periods of controlled increases and decreases in skin temperature (Ts) over the Ts range of 34-40 degrees C. One protocol was designed to observe changes in forearm blood flow (FBF) and heart rate (HR) with changes in core temperature (Tc; right atrial blood temperature and esophageal temperature were measured) with Ts held constant at two levels. FBF and HR changed linearly with Tc in the Tc range of 37-38 degrees C with Ts constant at 38 degrees C. A second protocol imposed Ts changes at two levels of Ts and Tc; this protocol also included a prolonged cooling period. The influence of Ts on FBF and HR was reduced when Ts changes occurred at an elevated Ts and Tc, and FBF showed considerable hysteresis during cooling. We conclude that a linear model for the control of FBF or HR is inadequate as a tool for predicting the control of these variables.

Adult↗