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Biomedical subjects

H Stern

Publications and source records attributed to H Stern.

At least 145 records · Page 8Linked to original sources
PubMed1980

Catamenial pneumothorax.

Five patients with catamenial pneumothorax are reported, four of whom had proven diaphragmatic defects. Two had microscopic diaphragmatic endometrial implants in the area of the defects. No specimen was obtained in two others. A fifth patient with the condition, as well as with extensive pelvic endometriosis, was treated successfully by closed thoracostomy followed by hysterectomy and salpingo-oophorectomy. Patients with recurrent catamenial pneumothorax should be assumed to have diaphragmatic defects and be considered for treatment by thoracotomy and closure of these defects if the severity of the condition warrants it.

Adult↗
PubMed1979

The effect of dephosphorylation on the properties of a helix-destabilizing protein from meiotic cells and its partial reversal by a protein kinase.

Properties of the helix-destabilizing protein from Lilium meiotic cells, 'R-protein', have been examined after treating it either with alkaline phosphatase or with two types of protein kinase. Dephosphorylation with the phosphatase increases binding capacity for single-strand DNA, but abolishes specificity of binding. Dephosphorylated R-protein binds equally to single and double-strand DNA. The capacity to facilitate denaturation or renaturation of DNA is also abolished by the treatment, but cooperativity characteristics are unaffected. The consequences of protein kinase treatment of native or dephosphorylated R-protein depend upon the origin of the kinase. Heterologous cyclic-AMP-dependent protein kinase cannot reverse the effects of dephosphorylation. However, it abolishes the binding affinity of either native or dephosphorylated R-protein for DNA. A protein kinase isolated from meiotic cells has no effect on the native protein, but it does restore all native properties tested to the dephosphorylated form after phosphorylating approximately two residues/molecule of protein.

Alkaline Phosphatase↗
PubMed1979

Isolation of mumps virus from the inner ear after sudden deafness.

A 26-year-old woman with bilateral otosclerosis underwent right stapedectomy with an excellent result. One year later, however, she developed symptoms of mumps and within two days was completely deaf in the right ear. Prompt surgical exploration excluded a complication of the otosclerosis and a perilymph fistula, but culture of a sample of perilymph grew mumps virus. The case provides direct evidence of a relation between mumps virus infection and inner-ear damage.

Adult↗
PubMed1979

A disruption of pachytene DNA metabolism in male mice with chromosomally-derived sterility.

DNA metabolism was analyzed in spermatocytes of mice that were sterile either because of X-autosome or autosome-autosome translocations, or because of trisomy. In the strains analyzed, spermatogenic development is arrested by metaphase I or soon thereafter. In all such strains a disruption of the normal pattern of pachytene DNA metabolism occurred. Prepachytene metabolism appeared normal. Disruption was manifest in both the level of endogenously generated nicks during pachytene and in the distribution of nicks among the different DNA sequence classes. Nicking was more intense in the steriles and tended to be randomized in distribution. Satellite DNA underwent pachytene nick-repair in the steriles but not in fertile controls. The repair capacity of spermatocytes from steriles was equal to that of the fertiles; the higher frequency of nicks in the steriles was due to a persistence of nicking activity.

Animals↗
PubMed1979

The mode of action alginic acid compound in the reduction of gastroesophageal reflux.

This study was designed to evaluate quantitatively the mode of action of alginic acid compound (AAC) in the treatment of patients with symptomatic gastroesophageal reflux. Gastroesophageal scintigraphy using an orall administered Tc-99m sulfur colloid solution was used to demonstrate that AAC decreased significantly the gastroesophageal reflux index from (9.9 +/- 1.3) % to (6.5 +/- 0.8) % (p less than 0.05). No alteration of lower esophageal sphincter pressure was observed. After ACC was suitably labeled with Sr-87m, a dual-nuclide scintigraphic technique was used to show that most (greater than 75%) of the AAC was located in the upper half of the stomach in both normal subjects and patients with gastroesophageal reflux. In those subjects in whom reflux did occur after treatment with AAC, the Sr-87m-AAC refluxed into the esophagus preferentially compared with the liquid containing Tc-99m sulfur colloid. These findings suggest that AAC dimishes gastroesophageal reflux by means of its foaming, floating, and viscous properties.

Adult↗
PubMed1978

Absence of satellite DNA synthesis during meiotic prophase in mouse and human spermatocytes.

Mouse spermatocytes were labelled in situ with 3H-thymidine at successive stages of meiosis. Isolated mouse as well as human spermatocytes were similarly labelled under in vitro conditions. DNA synthesis was followed either by tracking radioactivities in Cs2SO4 gradients or by measuring reassociation kinetics. Mouse satellite DNA and the 3 satellites of human DNA are labelled during S-phase but not during pachytene. In the mouse genome, there is a preferential labelling of regions containing foldbacks (human spermatocytes were not analyzed in this respect). The absence of detectable pachytene synthesis in satellite DNA is consistent with genetic evidence on the absence of crossing-over in constitutive heterochromatin.

Animals↗
PubMed1978

DNA unwinding protein from meiotic cells of Lilium.

An ATP-dependent DNA unwinding protein is present at a high level of activity in meiotic cells of lilies. The protein also acts as a DNA-dependent ATPase, the single strand form being the preferred cofactor. It binds in the absence of ATP to single-strand DNA and to ends or nicks in duplex DNA. A 3'-OH terminus is required for binding at duplex ends; such binding is highly stable. Unwinding occurs in the presence of ATP, and it is limited to about 50 base pairs per end or 400-500 base pairs per nick. The ATP hydrolyzed during unwinding is distinguishable from ATP hydrolysis in the presence of single-strand DNA.

Adenosine Triphosphatases↗
PubMed1978

Syncytium formation caused by human cytomegalovirus in human embryonic lung fibroblasts.

Large syncytia were regularly produced after prolonged infection in vitro of human embryonic fibroblasts by AD169 and other strains of human CMV. The syncytia showed typical CMV intranuclear inclusion bodies and herpesvirus particles in the nuclei and cytoplasm. It is proposed that syncytium formation follows abortive infection of the fibroblasts with defective virus.

Capsid↗
PubMed1977

Biochemical analysis of meiosis in the male mouse. I. Separation of DNA labelling of specific spermatogenic stages.

Spermatogenic cells of the mouse have been separated by gravity sedimentation using a modification of a previously published method. Details are given for the collection of purified samples of specific meiotic stages and for the collection of labelled cell fractions following injection of 3H-thymidine. Suppression of semi-conservative meiotic DNA synthesis, essential to the biochemical analysis of pachytene DNA metabolism, has been achieved by in vivo administration of 1 M hydroxyurea.

Animals↗
PubMed1977

Biochemical analysis of meiosis in the male mouse. II. DNA metabolism at pachytene.

The DNA metabolism of mouse spermatogenic cells was investigated by intravenous administration of isotope and Staput fractionation of the cells. The pattern of metabolism is virtually identical with that observed in Lilium microsporocytes. A programmed single strand nicking of DNA occure at pachytene such that at least 50% of the DNA is in the form of 62S fragments. Repair replication of endogenously nicked sites is fully achieved during pachytene. The sites of nicking and repair are preferentially located in sequences that are repeated about 400 times. These results are considered as strong evidence for a universal pattern of meiotic prophase DNA metabolism which is associated with crossing-over.

Animals↗
PubMed1977

Biochemistry of meiosis.

The process of meiosis in Lilium falls into four physiological stages - prezygotene, zygotene, pachytene, and post-pachytene. Each of these stages has distinctive metabolic characteristics. Commitment to meiosis occurs during the prezygotene interval at about the time when S-phase replication is completed. The activities following commitment are essential to synapsis inasmuch as perturbations of cells during that interval have subsequent effects on synapsis and crossing over. Just before the initiation of synapsis, a distinctive lipoprotein complex appears in the nucleus. The complex most probably functions in the process of pairing. Zygotene is marked by the delayed replication of specific intercalary segments of chromosomal DNA (Z-DNA), the replication being a necessary condition for ongoing synapsis. The replication occurs in the lipoprotein complex in the presence of a reassociation protein (r-protein). Z-DNA segments would appear to have other meiotic functions inasmuch as the replicated segments remain unligated to the body of chromosomal DNA until the beginning of chromosome disjunction. The pachytene interval is marked by an activation of endonucleolytic activity. The enzyme produces single-stranded nicks in the DNA at specific loci. These loci consist of moderately repeated segments; about 100-200 base pairs long. Extracellular agents, such as radiation, cause random nicking regardless of the meiotic stage at which they are applied. Localized nicking and repair are thus unique features of meiosis. The temporal segregation of metabolic activities concerned with pairing and crossing over and their operation in special chromosome regions constitute the most prominent features of the biochemical events associated with meiosis.

Carrier Proteins↗