Abrupt (< 1 day), acute (< 1 week), and early (< 1 month) vessel closure at the angioplasty site. Morphologic observations and causes of closure in 130 necropsy patients undergoing coronary angioplasty

While abundant clinical and angiographic data are available regarding features of acute or abrupt closure at the site of balloon angioplasty, little morphologic information is available. This study discusses morphologic-histologic causes for acute closure after angioplasty in 130 necropsy patients. Intimal-medial flaps, elastic recoil, and primary thrombosis were the three leading morphologic causes for closure. Data were subdivided into time categories: abrupt (< 1 day), acute (< 1 week), and early (< 1 month). Intimal-medial flaps remained the most common cause for angioplasty closure despite time from angioplasty to documented occlusion. Morphologic recognition of types and frequencies of angioplasty closure are discussed, and specific mechanical, pharmacologic, or combined treatments are reviewed.     

Mapping Escherichia coli elongation factor Tu residues involved in binding of aminoacyl-tRNA

Two residues of Escherichia coli elongation factor Tu involved in binding of aminoacyl-tRNA were identified and subjected to mutational analysis. Lys-89 and Asn-90 were each replaced by either Ala or Glu. The four single mutants were denoted K89A, K89E, N90A, and N90E, respectively. The mutants were characterized with respect to thermal and chemical stability, GTPase activity, tRNA affinity, and activity in an in vitro translation assay. Most conspicuously tRNA affinities were reduced for all mutants. The results verify our structural analysis of elongation factor Tu in complex with aminoacyl-tRNA, which suggested an important role of Lys-89 and Asn-90 in tRNA binding. Furthermore, our results indicate helix B to be an important target site for nucleotide exchange factor EF-Ts. Also the mutants His-66 to Ala and His-118 to either Ala or Glu were characterized in an in vitro translation assay. Their functional roles are discussed in relation to the structure of elongation factor Tu in complex with aminoacyl-tRNA.     

Induction of atypical squamous metaplasia with benzo[a]pyrene in cultured hamster tracheas

Areas of hyperplasia were produced in hamster tracheal epithelium maintained in vitro by exposure to a suspension of benzo[a]pyrene (BP) in gelatin. Typical and atypical epiodermoid metaplasia were seen by 2 weeks. In atypical areas, cell nuclei were enlarged with prominent nucleoli, the cytoplasm contained dense bundles of tonofilaments and the cells were joined by numerous desmosomes. The peak response to the carcinogen was reached 4 weeks after the application of BP and consisted of extensive atypical epidermoid metaplasia. Tracheas treated with gelatin alone maintained a columnar epithelium for 6 weeks of culture. The characteristics of the metaplastic changes in vitro are essentially identical to those described after exposure of the hamster tracheobronchial epithelium to benzo[a]pyrene-ferric oxide in vivo.     

Cholesterol and lipoprotein(a) as risk factors for coronary heart disease in elderly subjects

The changes in lipoprotein(a) concentration that occur with age as a result of its association with an increased risk of coronary artery disease were investigated. Lipoprotein(a) concentrations were measured in serum samples from healthy volunteers, individuals with premature coronary artery disease, individuals with hyperlipidaemia but without evidence of premature coronary artery disease, and also in elderly men and women who had hyperlipidaemia. Concentrations in individuals with premature coronary artery disease were the same as those of the healthy volunteers, while in both these groups they were lower than those found in hyperlipidaemic elderly men and women, and those found in hyperlipidaemic women aged 36-68 years. No association between raised lipoprotein(a) concentration and mortality as a result of premature coronary artery disease was demonstrated. Raised lipoprotein(a) levels found in the hyperlipidaemic individuals also suggested that it may not be an independent risk factor.     

Correlation between vascular and cellular responses to atrial natriuretic peptide and to sodium nitroprusside

Atrial natriuretic peptide (ANP) and sodium nitroprusside (SNP) increase cGMP in vascular smooth muscle cells and act as vasodilators in some, but not all, blood vessels. In this present study, we attempted to correlate the ability of these two agents to dilate blood vessels with the ability to increase cGMP in cultured vascular smooth muscle cells. In the isolated guinea pig heart, SNP dose-dependently increased coronary flow while ANP was ineffective. In smooth muscle cells cultured from the coronary system, SNP increased intracellular cGMP in a dose-dependent manner while ANP had no effect on cGMP in these cells. In isolated guinea-pig thoracic aorta, precontracted with K+, both ANP and SNP produced relaxation and ANP was the more potent. In smooth muscle cells cultured from the aorta, ANP and SNP increased cGMP and the potency relationship was similar to the intact vessel. These results support the view that phenotypic properties of vascular smooth muscle cells can account for differences in the response of blood vessels to vasodilators.     

Extracts of porcine pancreas prevent progression of hypercalcemia and cachexia and prolong survival in nude mice bearing a human squamous carcinoma

Porcine pancreatic extracts (PXs) have previously been shown to decrease blood ionized calcium in BALB/c mice (T. Yoneda, Y. Takaoka, and G. R. Mundy. FEBS Lett., 278: 171-174, 1991). In the present study, we show that the PX is effective in preventing progression of hypercalcemia and decreasing osteoclastic bone resorption associated with a human squamous carcinoma in nude mice. PX inhibited osteoclast-like cell formation in mouse bone marrow cultures and bone resorption in organ cultures of fetal rat long bones which had been stimulated by serum-free culture supernatants of this cancer. In addition, PX increased food intake, decreased weight loss, and prevented development of cachexia. In parallel with these effects, PX prolonged survival of tumor-bearing animals. PX might have therapeutic potential for management of hypercalcemia and cachexia associated with malignancy.     

Occupational blood exposures in dentistry: a decade in review

This review summarizes data from self-reported and observational studies describing the nature, frequency, and circumstances of occupational blood exposures among US dental workers between 1986 and 1995. These studies suggest that, among US dentists, percutaneous injuries have declined steadily over the 10-year period. Data also suggest that, in 1995, most dental workers (dentists, hygienists assistants, and oral surgeons) experienced approximately three injuries per year. Work practices (eg, using an instrument instead of fingers to retract tissue), safer instrumentation or design (eg, self-sheathing needles, changes in dental-unit design), and continued worker education may reduce occupational blood exposures in dentistry further.     

Codistribution of procathepsin B and mature cathepsin B forms in human prostate tumors detected by confocal and immunofluorescence microscopy

Ascorbic acid can recycle alpha-tocopherol from the tocopheroxyl free radical in lipid bilayers and in micelles, but such recycling has not been demonstrated to occur across cell membranes. In this work the ability of intracellular ascorbate to protect and to recycle alpha-tocopherol in intact human erythrocytes and erythrocyte ghosts was investigated. In erythrocytes that were 80% depleted of intracellular ascorbate by treatment with the nitroxide Tempol, both 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) and ferricyanide oxidized alpha-tocopherol to a greater extent than in cells not depleted of ascorbate. In contrast, in erythrocytes in which the intracellular ascorbate concentration had been increased by loading with dehydroascorbate, loss of alpha-tocopherol was less with both oxidants than in control cells. Protection against AAPH-induced oxidation of alpha-tocopherol was not prevented by extracellular ascorbate oxidase, indicating that the protection was due to intracellular and not to extracellular ascorbate. Incubation of erythrocytes with lecithin liposomes also generated an oxidant stress, which caused lipid peroxidation in the liposomes and depleted erythrocyte alpha-tocopherol, leading to hemolysis. Ascorbate loading of the erythrocytes delayed liposome oxidation and decreased loss of alpha-tocopherol from both cells and from alpha-tocopherol-loaded liposomes. When erythrocyte ghosts were resealed to contain ascorbate and challenged with free radicals generated by AAPH outside the ghosts, intravesicular ascorbate was totally depleted over 1 h of incubation, whereas alpha-tocopherol decreased only after ascorbate was substantially oxidized. These results suggest that ascorbate within the erythrocyte protects alpha-tocopherol in the cell membrane by a direct recycling mechanism.     

Socioeconomic status and use of family planning among Ghanaian government workers

The low utilization of family planning methods in Ghana, and by inference in much of Africa, is explained by reference to traditional sociocultural values held by males. A LISREL model is tested using data collected from educated males working in the Ghanaian government. Among the findings are that lack of couple communication, segregated conjugal role relationships, and male-dominated decision-making are all significant predictors of non-use of family planning methods (pronatalist attitude is not). Possession of knowledge of family planning among Ghanaian males alone is unlikely to initiate use of family planning methods. Additional sociodemographic and modernization findings are reported.