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Biomedical subjects

J Stern

Publications and source records attributed to J Stern.

At least 19 recordsLinked to original sources
PubMed1992

Black lipid membranes of tetraether lipids from Thermoplasma acidophilum.

Black lipid membranes were formed of tetraether lipids from Thermoplasma acidophilum and compared to the bilayer forming lipids diphytanoylphosphatidylcholine and diphythanylglucosylglycerol. Bilayer-forming lipids varied in thickness of black lipid membranes due to the organic solvent used. Measurements of the specific membrane capacitance (Cm = 0.744 microF/cm2) showed that the membrane-spanning tetraether lipids from Thermoplasma acidophilum form a monolayer of a constant thickness of 2.5-3.0 nm no matter from which solvent. This finding corresponds to the results of Gliozzi et al. for the lipids of another archaebacterium, Sulfolobus solfataricus. Black lipid membranes were formed at room temperature with a torus from bilayer-forming lipids, however, the torus could also be formed by the tetraether-lipid itself at room temperature and at defined concentration. In these stable black lipid membranes, conductance was measured in the presence of valinomycin, nonactin, and gramicidin. At 10(-7) M concentration, valinomycin mediated higher conductance in membranes from tetraether lipids (200-1200 microS/cm2) than from bilayer-forming lipids (125-480 microS/cm2). Nonactin, at 10(-6) M concentration, mediated a 6-fold higher conductance in a tetraether lipid membrane than in a bilayer, whereas conductance, in the presence of 5 x 10(-11) M gramicidin could reach higher values in bilayers than in tetraether lipid monolayers of comparable thickness. Monensin did not increase the conductance of black lipid membranes from tetraether lipids under all conditions applied in our experiments. Poly(L-lysine) destroyed black lipid membranes. Lipopolysaccharides from Thermoplasma acidophilum were not able to form stable black lipid membranes by themselves. The lipopolysaccharide complexes from Thermoplasma acidophilum and from Escherichia coli decreased the valinomycin-mediated conductance of monolayer and bilayer membranes. This influence was stronger than that of the polysaccharide dextran.

Electric Conductivity↗
PubMed1992

Rates and outcomes of planned pregnancy after use of Norplant capsules, Norplant II rods, or levonorgestrel-releasing or copper TCu 380Ag intrauterine contraceptive devices.

OBJECTIVES: The objectives were to measure rates of planned pregnancy and factors affecting these rates after use of very-long-acting contraceptive methods (Norplant or Norplant II implants, a levonorgestrel-releasing intrauterine contraceptive device, or the copper T (model TCu 380Ag) intrauterine contraceptive device. STUDY DESIGN: The design was a concurrent, multicenter prospective study of 372 women who stopped contraception for planned pregnancy. Analysis was by life-table, log-rank, and standard chi 2 methods. RESULTS: Pregnancy rates 12 and 24 months after cessation of contraceptive use were 82 and 89 per 100, respectively. Age at removal and family planning intentions at initiation of contraception were both significantly correlated with pregnancy rates (p less than 0.05), but former contraceptive regimen and duration of contraceptive use were not. Pregnancy outcomes did not deviate from normal limits and did not differ by contraceptive formerly used. CONCLUSION: Contraceptive implants releasing 30 micrograms/day of levonorgestrel or intrauterine contraceptive devices releasing 20 micrograms/day of levonorgestrel or having copper surface areas of 380 mm2 are associated with normal fertility after use for women seeking pregnancy at termination. Durations of use do not affect pregnancy rates.

Adult↗
PubMed1992

Color Doppler ultrasonography assessment of tubal patency: a comparison study with traditional techniques.

OBJECTIVE: To compare the results of color Doppler ultrasonic hysterosalpingography (color US-HSG) and x-ray-HSG with chromoperturbation at the time of laparoscopy. DESIGN: Open, uncontrolled study of women seeking evaluation for infertility from August 1989 to July 1991. SETTING: Clinical environment. PATIENTS: Two hundred thirty-eight infertile women. INTERVENTION: Saline was administered transcervically during transvaginal color Doppler sonography in 238 women. Traditional x-ray-HSG was performed in 89 women. Laparoscopy with chromoperturbation was done in 121 women. Forty-nine women had all three procedures performed. MAIN OUTCOME MEASURES: The frequency of diagnosis of bilateral tubal patency, bilateral tubal occlusion, and unilateral tubal patency after color US-HSG and x-ray-HSG was compared with chromoperturbation. The diagnostic efficacy of color US-HSG and x-ray-HSG was compared with chromoperturbation. RESULTS: Correlation between color US-HSG and x-ray findings with chromoperturbation occurred in 81% versus 60% (P = 0.0008) of all women studied. In 49 women who had all three procedures performed, color US-HSG results correlated with chromoperturbation more often than x-ray-HSG (82% versus 57%, P = 0.0152). CONCLUSION: Color US-HSG is an alternative technique to x-ray-HSG in diagnosing tubal occlusion as a cause of infertility.

Fallopian Tube Patency Tests↗
PubMed1991

Role of the mesopontine area in the circling behavior induced by apomorphine in rats bearing unilateral lesion of the entopeduncular nucleus.

The role of the mesopontine area and superior colliculus in turning behavior induced by systemic administration of apomorphine was studied in rats bearing a unilateral entopeduncular lesion. Bilateral electrolytic damage of the superior colliculus resulted in an enhancement of the ipsilateral circling response to apomorphine, perhaps as a consequence of an increased locomotor drive in such animals. Bilateral electrolytic lesions of the mesopontine area decreased apomorphine-induced turning in entopeduncular rats, while a bilateral kainic acid lesion of the same region was ineffective. It was concluded that the pedunculopontine nucleus and adjacent reticular formation are not an essential link for the striopallidal complex output mediating circling in this model. Fibers running through this region could be implicated in the expression of the behavior under study. Since a unilateral electrolytic lesion of the mesopontine area contralateral to the damaged entopeduncular nucleus reduced drug-induced turning, we propose that an uncrossed pathway from the intact striopallidal complex mediates circling in our rats.

Animals↗
PubMed1991

Effect of cyclosporine on ornithine decarboxylase activity in rat submaxillary lymph nodes: modulation by sympathetic nerves.

In order to examine whether cyclosporine activity in submaxillary lymph nodes is dependent on sympathetic modulation, rats received a unilateral superior cervical ganglionectomy together with a contralateral sham-operation. Two weeks later, cyclosporine (5 or 20 mg/kg per day s.c.) was injected for five days. Freund's complete adjuvant was injected 1 h before the third injection of cyclosporine and the rats were killed 2 h after the last injection of cyclosporine. A significant increase in ornithine decarboxylase activity in submaxillary lymph nodes was observed two weeks after sympathetic denervation. Cyclosporine decreased enzyme activity in submaxillary lymph nodes on the sham-operated side by 67-77% and by 21-41% on the denervated side (P less than 0.01). The incorporation of [35S]methionine into proteins in ipsilateral submaxillary lymph nodes was increased by unilateral superior cervical ganglionectomy and decreased by cyclosporine to a similar extent in denervated and innervated lymph nodes. Superior cervical ganglionectomy decreased by about 93-95% the norepinephrine content of submaxillary lymph nodes regardless of cyclosporine treatment. The results indicate that an appropriate sympathetic neural environment is needed for cyclosporine to have an effect on ornithine decarboxylase activity in lymphoid tissue.

Animals↗
PubMed1991

Hypothyroidism following combined treatment for hypopharyngeal and laryngeal carcinoma.

The development of hypothyroidism following combined treatment for pharyngeal and laryngeal cancer has received little attention in the literature. We prospectively studied 32 patients over 4 years to determine the incidence of such hypothyroidism and to examine the effect of hemithyroidectomy associated with a combined treatment modality. All patients were men with pharyngeal or laryngeal squamous cell carcinomas and no prior history of thyroid disease. Treatment consisted of radical surgery (30 of 32 patients), followed by postoperative radiotherapy (31 patients). The results of thyroid function tests (free triiodothyronine, free thyroxine, and thyroid-stimulating hormone [TSH]) were all normal preoperatively; tests were repeated every 3 months after treatment. Elevation of TSH values in two successive blood samples was required to make a diagnosis of hypothyroidism. Of 12 patients who underwent hemithyroidectomy as part of total pharyngolaryngectomy and postoperative radiotherapy, 7 became hypothyroid a mean of 6 months after treatment. Twenty patients had similar combined treatment but without thyroid resection. Hypothyroidism developed a mean of 10 months after treatment in only four patients in this group (p less than 0.05). We conclude that hypothyroidism frequently develops following combined treatment for pharyngeal and laryngeal cancer even when thyroid resection has not been performed. Patients should be evaluated postoperatively and carefully monitored by means of serial thyroid function tests.

Carcinoma, Squamous Cell↗
PubMed1991

Prolonged intrauterine contraception: a seven-year randomized study of the levonorgestrel 20 mcg/day (LNg 20) and the Copper T380 Ag IUDS.

A levonorgestrel-releasing IUD and the Copper T 380Ag IUD were in randomized comparison for seven years in five clinics. In two other clinics the randomized study was truncated at five years, but use of the Copper T continued. No pregnancies occurred to users of either device in years 6 and 7. Cumulative pregnancy rates were 1.1 per 100 at seven years for the steroid-releasing and 1.4 per 100 for the copper-releasing IUDs. Cumulative rates of PID did not differ between devices. Infection rates appeared to be lowest during the sixth and seventh years of the study. Termination attributable to amenorrhea was the principal contributor to differences in cumulative continuation rates between devices. At the five clinics that carried the comparative study to seven years, cumulative continuation rates were 24.9 per 100 for LNg20 IUD users and 29.4 per 100 for TCu 380Ag users. Women who used either method for periods of five to seven years experienced, on average, marked to mild increases in hemoglobin as compared with levels at admission. The Copper T380 family and the LNg20 IUDs represent the most effective reversible contraceptive methods yet studied in long-term randomized trials.

Adolescent↗
PubMed1991

Two-year comparative trial of the Gyne T* 380 Slimline and Gyne T* 380 intrauterine copper devices.

In a randomized trial of the Gyne T* 380 Slimline, the-two year pregnancy rate was 0.3 per 100 and the continuation rate was 65 per 100. These rates did not differ statistically from those of the standard Gyne T* 380, nor did other performance parameters differ between devices by the log-rank test. Women under age 30 had lower continuation rates using either device than did women age 30 or older at admission because of removals for planned pregnancy. Conception rates among those who desired pregnancy were 35 per 100 at one month and 86 per 100 at one year.

Adult↗
PubMed1991

Lung scintigraphy in pulmonary capillary hemangiomatosis. A rare disorder causing primary pulmonary hypertension.

The authors report the results of lung scintigraphy in two patients with primary pulmonary hypertension caused by pulmonary capillary hemangiomatosis, a rare disorder resulting from the proliferation of histologically normal capillaries in the lung. Perfusion studies revealed a nonhomogeneous pattern with some focal defects, similar to that seen with some other histologic types of primary pulmonary hypertension. The mechanisms underlying this perfusion pattern are unknown.

Adult↗
PubMed1991

Transcriptional role of a conserved GATA-1 site in the human epsilon-globin gene promoter.

The epsilon-globin gene is the first of the human beta-like globin genes to be expressed during development. We have analyzed protein-DNA interactions in the epsilon-globin promoter region by DNase I footprinting and electrophoretic mobility shift experiments using nuclear extracts from K562 human erythroid cells and from nonerythroid HeLa cells. A restricted set of ubiquitous proteins, including Sp1, bound to regions of the promoter including the CACCC and CCAAT sites. Three interactions, at positions -213, -165, and +3 relative to the transcription start site, were erythroid specific and corresponded to binding of GATA-1, a transcription factor highly restricted to the erythroid lineage. Interestingly, the GATA-1 site at -165 has been conserved in the promoters of 10 mammalian embryonic globin genes. Point mutations demonstrate that GATA-1 binding to this site is necessary for interaction with an erythroid-specific enhancer but that in the absence of an enhancer, GATA-1 does not increase transcription.

Animals↗
PubMed1991

Chronic tophaceous gout. A case report.

A review of gout is presented, followed by a discussion of the current medical literature on diagnosis, differential diagnosis, staging, and treatment. Chronic tophaceous gout is not as prevalent as it once was because of early diagnosis and treatment, but it is still encountered in the podiatric practice. A severe case of chronic tophaceous gout is presented. The patient was successfully treated by surgical intervention. Although surgery may be avoided in most cases, it is indicated when intractable pain, loss of motion, and massive joint destruction are present.

Chronic Disease↗
PubMed1991

Child's pain.

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Child↗
PubMed1991

Reversible lactose malabsorption and intolerance in Graves' disease.

Ten patients with untreated Graves' disease underwent tests to determine lactose absorption, liquid gastric emptying, and oral cecal transit time. To determine the influence of thyroid hormone status on lactose absorption, eight of these same patients had repeat studies when rendered euthyroid. Two of these eight patients also underwent studies while transiently hypothyroid. Motility studies were also evaluated in a group of 11 control subjects. Lactose malabsorption occurred in nine patients with Graves' disease. In seven patients who repeated these studies, lactose malabsorption normalized in three, symptoms induced by lactose improved in two and were unchanged in two. However, these latter two patients appeared to have improved symptoms in the transient hypothyroid state. Liquid gastric emptying was significantly faster in untreated patients than controls and treated self-same patients. Transit time was significantly faster in untreated patients than when they were rendered euthyroid. There may be a relationship between altered lactose absorption states and changes in intestinal motility in patients with Graves' disease.

Adult↗