[Rheumatic diseases in Zimbabwe].
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Humans↗
Biomedical subjects
M Stein
Publications and source records attributed to M Stein.
An analysis of the biomechanical mechanism of tibial stress fractures among Israeli infantry recruits. A prospective study.
The biomechanical mechanism of tibial diaphyseal stress fractures was studied prospectively in a group of 286 Israeli recruits. Before training each recruit had roentgenograms taken of his tibiae. Measurements of total tibial and cortical widths in the anteroposterior (AP) and mediolateral planes were made on these roentgenograms at two levels: at the point of the narrowest tibial width on AP roentgenograms (Level 1) and at the point of the narrowest width on lateral roentgenograms (Level 2). The tibial cross section was idealized as an eccentric ellipse within an ellipse, and on the basis of measurements taken from the roentgenograms, the cross-sectional area (compression strength), area moments of inertia about AP and mediolateral axes of bending (bending strength), and the area polar moment of inertia (torsional strength) were calculated for each cross section. During the course of 14 weeks of training, 20% of the recruits sustained tibial diaphyseal stress fractures, all of which were along the medial cortex. Using stepwise logistic regression analysis the tibia's bending strength along an AP axis of bedding at Level 2 was found to be the most significant factor determining whether or not a recruit would develop a tibial stress fracture.
Adult↗
Factors influencing results of femoropopliteal bypass operations for lower limb ischemia.
An ideal way to assess the effectiveness of femoropopliteal bypass procedures is to standardize patient- and surgeon-related variables by randomization. Through statistical analysis of multiple factors influencing patency, limb loss, death rate and hospital stay, the authors reviewed retrospectively 136 bypass procedures performed over 5 years. Variables that contributed significantly to the results were: preoperative symptoms (p = 0.037), graft material used (p = 0.016), age of the patient (p = 0.007), adequacy of runoff (p = 0.041) and smoking postoperatively (p = 0.013). Autogenous vein grafts were superior to prosthetic grafts, the cumulative patency at 5 years being 67.5% and 38.2% respectively. The authors emphasize that all patients needing vascular surgery should be advised to stop smoking, since in this study postoperative smoking increased the probability of limb loss and adversely affected the cumulative patency rate by interaction with other variables such as preoperative symptoms, graft material and age.
Adult↗
The effect of chaotropic anions on the activation and the activity of spinach chloroplast fructose-1,6-bisphosphatase.
The effect of chaotropic anions was studied on processes that constitute the chloroplast fructose-1,6-bisphosphatase reaction, i.e. enzyme activation and catalysis. The specific activity of chloroplast fructose-1,6-bisphosphatase was enhanced by preincubation with dithiothreitol, fructose 1,6-bisphosphate, Ca2+, and a chaotropic anion. When chaotropes were ranked in the order of increasing concentrations required for maximal activation they followed a lyotropic (Hofmeister) series: SCN- less than Cl3C-COO- less than ClO4- less than I- less than Br- less than Cl- less than SO4(2-). On the contrary, salts inhibited the catalytic step. The stimulation of chloroplast fructose-1,6-bisphosphatase by chaotropic anions arose from a decrease of the activation kinetic constants of both fructose 1,6-bisphosphate and Ca2+; on the other hand, in catalysis neutral salts caused a decrease of kcat because the S0.5 for both fructose 1,6-bisphosphate and Mg2+ remained unaltered. The molecular weight of chloroplast fructose-1,6-bisphosphatase did not change after the activation by incubation with dithiothreitol, fructose 1,6-bisphosphate, Ca2+, and a chaotrope; consequently, the action of these modulators altered the conformation of the enzyme. Modification in the relative position of aromatic residues of chloroplast fructose-1,6-bisphosphatase was detected by UV differential spectroscopy. In addition, the concerted action of modulators made the enzyme more sensitive to (a) trypsin attack and (b) S-carboxymethylation by iodoacetamide. These results provide a new insight on the mechanism of light-mediated regulation of chloroplast fructose-1,6-bisphosphatase; concurrently to the action of a sugar bisphosphate, a bivalent cation, and a reductant, modifications of hydrophobic interactions in the structure of chloroplast fructose-1,6-bisphosphatase play a crucial role in the enhancement of the specific activity.
Anions↗
[Radiotherapy of early glottic carcinoma].
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Actuarial Analysis↗
Splenomegaly and solitary spleen metastasis in solid tumors.
Metastasis to the spleen from various neoplasms is very rare. Most of the splenic metastases are found at autopsy, and are part of a widespread disease. Four patients had cervical cancer (1 patient), endometrial cancer (1 patient), lung carcinoma (1 patient), and malignant melanoma (1 patient). All patients had splenic involvement without pathologic evidence of lymph node metastasis, and all underwent splenectomy. Three of the four presented with painful splenomegaly. The time from diagnosis to the development of splenic metastasis varied from 20 to 24 months. Two of the four patients had postoperative radiotherapy, one patient received intraperitoneal chemotherapy, and the patient with the melanoma received adjuvant chemotherapy. The rarity of solitary spleen metastasis from solid tumors and the treatment modalities are discussed.
Adult↗
Mr 46,000 mannose 6-phosphate specific receptor: its role in targeting of lysosomal enzymes.
Antibodies that block the ligand binding site of the cation-dependent mannose 6-phosphate specific receptor (Mr 46,000 MPR) were used to probe the function of the receptor in transport of lysosomal enzymes. Addition of the antibodies to the medium of Morris hepatoma 7777 cells, which express only the Mr 46,000 MPR, resulted in a decreased intracellular retention and increased secretion of newly synthesized lysosomal enzymes. In fibroblasts and HepG2 cells that express the cation-independent mannose 6-phosphate specific receptor (Mr 215,000 MPR) in addition to the Mr 46,000 MPR, antibodies against the Mr 46,000 MPR inhibited the intracellular retention of newly synthesized lysosomal enzymes only when added to the medium together with antibodies against the Mr 215,000 MPR. Morris hepatoma (M.H.) 7777 did not endocytose lysosomal enzymes, while U937 monocytes, which express both types of MPR, internalized lysosomal enzymes. The uptake was inhibited by antibodies against the Mr 215,000 MPR, but not by antibodies against the Mr 46,000 MPR. These observations suggest that Mr 46,000 MPR mediates transport of endogenous but not endocytosis of exogenous lysosomal enzymes. Internalization of receptor antibodies indicated that the failure to mediate endocytosis of lysosomal enzymes is due to an inability of surface Mr 46,000 MPR to bind ligands rather than its exclusion from the plasma membrane or from internalization.
Animals↗
The product of the mei3+ gene, expressed under control of the mating-type locus, induces meiosis and sporulation in fission yeast.
In fission yeast the ability to undergo meiosis and sporulation is conferred by the matP+ and matM+ genes of the mating-type locus. Inactivation of ran1+, a negative regulator of meiosis, is thought to be an essential step in meiotic initiation. We have isolated a further meiotic control gene mei3+, and have shown the following: a null allele of mei3 totally inhibits meiosis; the mei3+ RNA transcript and its translational product are expressed only in matP+/matM+ diploids entering meiosis; forced expression of mei3+ in vegetative cells provokes haploid meiosis and sporulation. We suggest that the product of mei3+ gene, a protein of 21 kd, initiates meiosis by inactivating ran1+.
Alleles↗
Leptomeningeal involvement by epithelial ovarian carcinoma: a case report.
A patient with epithelial ovarian carcinoma, who developed meningeal carcinomatosis, is hereby presented. A review of the literature revealed that only a few cases of this entity have been reported. With the prolonged survival of ovarian cancer patients treated by combination chemotherapy, it is expected that meningeal involvement will be found more often.
Cystadenocarcinoma↗
Pulmonary injury in burned patients.
Inhalation injury has emerged as the number one cause of fatality in the burn patient. Fiberoptic bronchoscopy and 133Xe scanning complement traditional clinical signs of inhalation injury and have led to discovery of a higher incidence of these injuries among patients with burns. Patients with inhalation injury typically demonstrate three stages: acute pulmonary insufficiency, pulmonary edema, and bronchopneumonia, all of which carry at least 50 per cent mortality rates. The major early pathophysiologic changes in the lungs of burned patients are related to upper-airway obstruction and lower-airway permeability edema. Treatment consists of intubation for signs of respiratory distress, pulmonary toilet, humidification of inspired air, and antibiotics for documented infection.
Adolescent↗
Cloning of a cDNA encoding the human cation-dependent mannose 6-phosphate-specific receptor.
Complementary DNA clones for the human cation-dependent mannose 6-phosphate-specific receptor have been isolated from a human placenta library in lambda gt11. The nucleotide sequence of the 2463-base-pair cDNA insert includes a 145-base-pair 5' untranslated region, an open reading frame of 831 base pairs corresponding to 277 amino acids (Mr = 30,993), and a 1487-base-pair 3' untranslated region. The deduced amino acid sequence is colinear with that determined by amino acid sequencing of the N-terminus peptide (41 residues) and nine tryptic peptides (93 additional residues). The receptor is synthesized as a precursor with a signal peptide of 20 amino acids. The hydrophobicity profile of the receptor indicates a single membrane-spanning domain, which separates an N-terminal region containing five potential N-glycosylation sites from a C-terminal region lacking N-glycosylation sites. Thus the N-terminal (Mr = 18,299) and C-terminal (Mr less than or equal to 7648) segments of the mature receptor are assumed to be exposed to the extracytosolic and cytosolic sides of the membrane, respectively. Analysis of a panel of somatic cell (mouse-human) hybrids shows that the gene for the receptor is located on human chromosome 12.
Amino Acid Sequence↗
Sucl+ encodes a predicted 13-kilodalton protein that is essential for cell viability and is directly involved in the division cycle of Schizosaccharomyces pombe.
Sucl+ was originally identified as a DNA sequence that, at high copy number, rescued Schizosaccharomyces pombe strains carrying certain temperature-sensitive alleles of the cdc2 cell cycle control gene. We determined the nucleotide sequence of a 1,083-base-pair Sucl+ DNA fragment and S1 mapped its 866-nucleotide RNA transcript. The protein-coding sequence of the gene is interrupted by two intervening sequences of 115 and 51 base pairs. The predicted translational product of the gene is a protein of 13 kilodaltons. A chromosomal gene disruption of Sucl+ was constructed in a diploid S. pombe strain. Germinating spores carrying a null allele of the gene were capable of very limited cell division, following which many cells became highly elongated. The Sucl+ gene was also strongly overexpressed under the control of a heterologous S. pombe promoter. Overexpression of Sucl+ is not lethal but causes a division delay such that cells are approximately twice the normal length at division. These data suggest that Sucl+ encodes a protein which plays a direct role in the cell division cycle of S. pombe.
Alleles↗
Treatment of advanced gastric cancer with DDP (cisplatin), adriamycin, and 5-fluorouracil (DAF).
Sixteen evaluable patients with advanced gastric cancer who had no prior therapy were treated intravenously with cisplatin (DDP) 20 mg/m2/day on days 1-5 and with Adriamycin 40 mg/m2 and 5-fluorouracil 600 mg/m2 on day 1 (DAF) every 3 weeks. There were five objective partial responses, giving a response rate of 31%. Five patients had minor responses, and 5 others achieved disease stabilization. The median duration of response for responders was 10 months, and the median time to tumor progression in nonresponders was 6 months. The overall median survival was 12 months (responders 14 months, nonresponders 9 months; NS). Most patients had a subjective improvement, including disappearance of abdominal pain (7/9) and gastrointestinal bleeding (5/7). The drug toxicity was moderate to severe. The primary nonhematologic toxicities were nausea and vomiting (in all patients), severe weakness (44%), and parasthesias (31%). Eight patients (50%) experienced significant bone marrow suppression. The DAF combination appears to have some activity in patients with advanced gastric cancer. However, further efforts in new drug development and other combinations are needed to improve the results of chemotherapy in stomach cancer.
Adenocarcinoma↗
Mutations affecting transport and stability of lysosomal enzymes.
The biosynthesis, post-translational processing and receptor-mediated transport of lysosomal enzymes will be briefly summarized. Mutations affecting the transport or the stability of a lysosomal enzyme but not its catalytic properties can result in a lysosomal storage disorder. Mutations causing a loss of catalytic activity may in addition affect transport or stability. Such mutations should not be classified as transport or stability mutations. Prototypes for transport and stability mutations are I-cell disease and late onset forms of metachromatic leukodystrophy.
Carrier Proteins↗
Stress fractures and tibial bone width. A risk factor.
A prospective study of 295 infantry recruits has shown that the mediolateral width of the tibia measured radiographically at each of three different levels in the bone had a statistically significant correlation with the total incidence of stress fractures as well as with those in the tibia alone or the femur alone. A narrow tibial width was shown to be a risk factor, but cortical thickness was not found to be significant.
Femoral Fractures↗
Effects of differentiation-inducing agents on synthesis, maturation and secretion of cathepsin D in U937 and HL-60 cells.
Treatment of human monocyte U937 and promyelocyte HL-60 cultures with agents known to induce differentiation (12-O-tetra-decanoylphorbol 13-acetate, calcitriol and dimethylsulfoxide) accelerates the maturation of cathepsin D and enhances the incorporation of [35S]methionine into cathepsin D. The most pronounced effects are obtained with calcitriol, which at a concentration of 10(-7) M increases the incorporation of [35S]methionine into cathepsin D from 0.08% to 0.4% of the detergent-soluble radioactivity. In addition, this treatment enhances the secretion of cathepsin D from about 8% to greater than or equal to 16% of the newly synthesized enzyme. In the presence of 10mM NH4Cl approximately half of the produced cathepsin D is secreted in both control and calcitriol-treated cells. It appears that in U937 cells two mechanisms are involved in sorting of cathepsin D. One of these is sensitive to NH4Cl and its efficiency is selectively decreased in cells pretreated with calcitriol.
Ammonium Chloride↗
46-kDa mannose 6-phosphate-specific receptor: purification, subunit composition, chemical modification.
A cation-dependent mannose 6-phosphate-specific receptor has recently been isolated from murine P388D1 macrophages and bovine liver (B. Hoflack & S. Kornfeld, (1985) J. Biol. Chem. 260, 12008-12014). The receptor purified from human liver has a subunit molecular size of 43 kDa, is rich in hydrophobic and charged amino acids and contains threonine at the N-terminus. The receptors from human and rat liver are antigenically related. Both are immunologically distinct from the cation-independent 215-kDa mannose 6-phosphate-specific receptor from human liver. Cross-linking experiments indicate that the cation-dependent receptor exists in solution as a tetramer. Modification of arginine and histidine residues, reduced drastically the binding of the receptor to immobilized ligands. Presence of mannose 6-phosphate during modification of arginine residues protected the binding properties of the receptor, suggesting that arginine is a constituent of the mannose 6-phosphate binding site of the receptor. The significance of the inability of histidine-modified receptors to bind ligands remains to be established.
Amino Acids↗
46-kDa mannose 6-phosphate-specific receptor: biosynthesis, processing, subcellular location and topology.
Synthesis of the cation-dependent mannose 6-phosphate-specific receptor was followed in cells of human (fibroblasts, Hep G2 cells, U937 monocytes, blood-derived macrophages) or rat (Morris hepatoma 7777 cells) origin. The mature form of the receptor has an apparent molecular size of 46 kDa except in fibroblasts, where the apparent molecular size was 43 kDa. The receptor contains 7-8 N-linked oligosaccharide chains, about 5 of which are converted into endo H-resistant forms within 2 h of synthesis. A small fraction of the receptor (about 3% of total in U937 monocytes) is located at the cell surface while the bulk of the receptor resides in internal membranes. Part of the internal receptors (20% in fibroblasts) resides in membranes of the endocytic pathway. The receptor was not detectable in dense lysosomes. The receptor is a hydrophobic transmembrane protein partitioning with Triton X-114. The cytosolic portion of the receptor comprises a molecular size of about 5 kDa and contains the C-terminus. The luminal (or external) portion of the receptor comprises a molecular size of greater than or equal to 37.5 kDa, of which more than half is represented by carbohydrate. Cross-linking experiments suggest that the mature receptor exists in membranes as a dimer.
Animals↗