Effect of extracellular Mg concentration on electrically induced contractions of rat vas deferens in vitro.

Contraction of smooth muscles of the vas deferens plays an important role in the propulsion of sperm into the pelvic urethra. This study examined the influence of external Mg2+ concentration on reactivity of the rat vas deferens to electrical stimulation in vitro. Vasa deferentia isolated from adult male rats were set up in tissue baths containing physiological salt solution at 37 degrees C and were stimulated electrically. Thereafter, increasing concentrations of Mg2+ were added to the bath and their effects on electrically evoked contractions were recorded. The effect of external Mg2+ depletion on evoked contractions was also examined. External Mg2+ depletion enhanced the contractile response to electrical stimulation while increasing external Mg2+ concentration inhibited the contractions. The inhibitory effect of Mg2+ was partially reversed by increasing extracellular Ca2+ concentration and was not additive with nifedipine. The results indicate that reactivity of the vas deferens to electrical stimulation is modulated by extracellular Mg2+ concentration. The possible relevance of these data to sperm transport through the vas deferens is discussed.

Magnesium in human semen: possible role in premature ejaculation.

Although magnesium is involved in many biological process and it is found higher levels in semen than serum, its role in human semen has not been elucidated. This investigation was conducted to evaluate the relationship between premature ejaculation and the levels of seminal magnesium. The levels of magnesium, zinc, copper, and selenium were evaluated with an atomic absorption spectrophotometer in serum and seminal plasma in 3 groups of men: (a) normal sperm parameters (15) (b) oligoasthenozoospermia (15), and genuine premature ejaculation (9). There were normal serum and semen levels of all the elements in the three groups, but significantly lower seminal plasma magnesium levels in men with premature ejaculation. The hormonal profile, body mass index (BMI) had no association with premature ejaculation. Decreased levels of magnesium gives rise to vasoconstriction from increased thromboxane level, increased endothelial intracellular Ca2+, and decreased nitric oxide. This may lead to premature emission and ejaculation processes. Magnesium is probably involved in semen transport. More research into the role of magnesium in the male physiology of reproductive tract, especially its association with premature ejaculation, is advocated.

Bacterial translocation in thioacetamide induced liver cirrhosis in rats.

Cirrhotic liver is predisposed to bacterial infections. Different species of bacteria including Escherichia coli, Enterobacter and Bacteroides fragilis were found to colonize thioacetamide-induced cirrhotic rat liver. Zinc treatment of the cirrhotic rats significantly corrected the histological and histochemical changes in the liver. However, this reversal with zinc treatment was not accompanied by any change in the bacterial colonies in the liver. The study shows that cirrhosis predisposes liver to bacterial colonization and the process is not reversible despite the partial reversal of the cirrhotic changes.

Effect of dietary selenium, zinc and allopurinol supplements on plasma and tissue manganese levels in rats with thioacetamide [correction of thiocetamide]-induced liver cirrhosis.

The effect of thioacetamide-induced liver cirrhosis on plasma and tissue manganese levels and the protective role of selenium, zinc and allopurinol supplements was investigated in rats. Control plasma and liver manganese (Mn) levels were found to be (mean +/- SD): 8.4 +/- 2.4 mg/L and 5.7 +/- 1.5 mg/g wet weight respectively. Plasma manganese levels were significantly increased (p < 0.001) whereas liver manganese levels were significantly reduced (p < 0.05) in the cirrhotic rats. Treatment with selenium, zinc and allopurinol reversed this trend and restored the manganese levels close to the normal values. Lung, spleen, and kidney manganese levels under control conditions were considerably lower than that of the liver tissue. However, these levels registered a significant increase (p < 0.05) in cirrhotic rats and this change was normalized after selenium, zinc and allopurinol treatment. There were no significant differences in the comparative efficacy of each of these protective agents. Zinc supplement considerably increased the plasma zinc levels and plasma Zn/Mn ratio had a good correlation with plasma zinc concentration. This ratio was significantly reduced in cirrhotic rats, but returned to the control level after zinc, selenium and allopurinol treatment. The results of this study indicate that the trace element, manganese, plays an important role in stabilizing cell structure and that this effect is mediated possibly by preserving the antioxidant activity of the tissues.

Intracellular distribution of Ca2+-Mg2+ adenosine triphosphatase (ATPase) in various tissues.

The cytochemical distribution of Ca2+-Mg2+-ATPase was studied ultrastructurally, using a lead capture method at pH 8.5 and compared in various tissues. In thymic, splenic and activated peripheral blood lymphocytes and in cultured HeLa cells activity was consistently localised on the nuclear envelope, endoplasmic reticulum, Golgi apparatus, mitochondria and weakly on centrioles, but not on the plasma membrane. Intracellular activity was similarly distributed in intestinal absorptive cells where activity was particularly strong in the Golgi apparatus, and in hepatocytes where, however, activity was generally weak. Intracellular activity was lacking in renal glomerular and tubular cells and in cerebellar neurons and neuroglia. Variable activity was present on the outer surface of the plasma membrane, particularly on the brush borders of intestinal and renal tubular absorptive cells, the basolateral invaginations of distal tubules and the bile canaliculi. Mitochondrial activity, when present, was inhibited by oligomycin. The localisation at different sites may represent biochemically different ATPases including endoplasmic reticular ATPase involved in intracellular calcium regulation, oligomycin-sensitive mitochondrial ATPase, dynein-like ATPase associated with centrioles and an ectoenzyme associated with cell surface specialisations.

Ultrastructural localization of adenosine triphosphatase activity in HeLa cells at various stages of the cell cycle.

HeLa cells in a monolayer culture were synchronized to S, G2 and mitotic phases by use of excess (2.5 mM) deoxythymidine double-block technique. The localizations of Ca2++-activated adenosine triphosphatase (ATPase) at different phases of the cell cycle were studied using light- and electron-microscopic histochemical techniques, and microphotometric comparisons of the densities of reaction products. Enzyme reaction product was always localized in the endoplasmic reticulum, nuclear membrane, mitochondria and Golgi apparatus, but there were qualitative and quantitative differences related to the phases of the cell cycle. In S phase the activity was mainly concentrated in a perinuclear area of the cytoplasm whereas in G2 and mitosis the activity was scattered throughout the cell. The total activity per cell was maximal in G2, was less in S phase and least in mitosis. Activity in the mitochondria and endoplasmic reticulum was distinctly less in mitosis than in other phases of the cell cycle. The mitochondrial ATPase differed from the ATPase at other sites in ion dependence and sensitivity to oligomycin. The results suggest that there may be several distinct ATPases in proliferating cells.

Immunohistochemical localization of collagens and fibronectin in human breast neoplasms.

Forty four specimens from neoplastic, hyperplastic and normal human breast tissues were studied for localization of collagens and fibronectin. Affinity purified antihuman type I, III and IV collagens and antifibronectins were utilized by the indirect immunoperoxidase technique on fixed and paraffin-embedded sections. 86% of the cell cytoplasm of infiltrating ductal and 83% of the lobular cancers were positively stained for collagen type I and III. Collagen type IV, however, was detected in 100% of infiltrating ductal and 83% of lobular carcinomas. Focal cytoplasmic staining is a predominant feature for all antigens in the intraduct carcinoma while a diffuse pattern is encountered in the infiltrating types. Intact basement membranes in various lesions always stained for type IV collagen and showed variable staining for type III collagen and fibronectin. Epithelia of normal, benign, hyperplastic breast and most medullary carcinoma were negative for the three collagen types. Our results are in favour of the view that infiltrating breast carcinoma cells produce inappropriately the majority of collagens and inconsistently other proteins such as fibronectin.

Expression of connective tissue stromal elements in human cholangiocarcinomas. An immunohistochemical and ultrastructural study.

The results of the study of ten cholangiocarcinomas from intrahepatic or extrahepatic origins are reported. Using both light microscopic immunohistochemistry and transmission electron microscopy the scirrhous stroma of the tumour showed clear evidence for the production of its collagenous, elastic and possibly other fibrillar elements by the neoplastic cells. Our findings refute the view that the occasional spindle cells (i.e. fibroblasts, myofibroblasts or even smooth muscle cells) could play a major role in the production of such a voluminous amount of the various connective tissue elements. Therefore, it seems reasonable to suggest that the scirrhous stroma of cholangiocarcinomas is produced by the malignant cells similar to those of the breast, oesophagus, stomach and ureter.

Energy status in HeLa cells after treatment with an arresting anticancer drug.

The energy status of HeLa cells arrested in the G2 phase of the cell cycle by the antineoplastic agent cis-acid was compared with that of normal G2-phase-synchronized cells. The results showed that treatment with the drug has significantly decreased the adenylate pool, adenylate energy charge and phosphorylation potential.

Patterns of stromal elements in an implanted ureteric transitional cell carcinoma. An immunohistochemical and ultrastructural study.

The results of the study of three implanted ureteric tumors from a primary transitional cell carcinoma of the renal pelvis are reported. Using both light microscopic immunohistochemistry and transmission electron microscopy, the stroma of the tumor showed consistent evidence for the production of at least its collagenous component by the neoplastic cells. Our findings argue with the notion that occasional fibroblasts and other cells of mesenchymal origin could play a major role in this phenomenon. Therefore, it seems plausible to suggest that what is happening in these tumors is similar to the behavior of malignant cells in scirrhous 'infiltrating' carcinoma of the breast and other sites.

Distribution and ultrastructural characterization of the stroma in scirrhous 'infiltrating' carcinoma of the human breast.

A combination of light microscopic, histochemical, immunohistochemical and transmission electron microscopic techniques were used to study the distribution and ultrastructural characterization of the stroma of Scirrhous 'infiltrating' carcinoma of the human breast. Both the light and electron microscopic techniques emphasized the presence of regional variations in the distribution of fibrous tissue in this type of tumour. Whilst fibronectin and collagen type III appeared relatively rich in both periductal and diffused regions, there was a clear contrast in the distribution of collagen type I and elastic tissue between the two regions. Collagen type I was more numerous in the diffused regions whereas elastic tissue was more produced in the periductal regions. The present study confirmed the views that Scirrhous carcinoma cells secrete inappropriately the majority of collagen, elastic and possibly other fibrillar elements of the connective tissue stroma. Fibroblasts, myofibroblasts and myoepithelial cells are believed to contribute in a minor way to the production of the various connective tissue elements. Finally, our findings have been discussed in relation to the mechanism of invasiveness of the tumour cells.

Ultrastructural changes in HeLa cells following treatment with the antineoplastic agent cis-acid.

The ultrastructure of HeLa cells arrested in the G2 phase of the cell cycle by the antineoplastic agent cis-acid was studied and compared with that of normal G2-phase-synchronized cells. The results demonstrate that the chromatin of drug-treated cells was fragmented and clumped, the membranous structures had degenerated or were destroyed and the polyribosomes were decreased. The mitochondria were swollen and vacuolated, suggesting that energy production might have been impaired.

Induction of prematurely condensed chromosomes by mitoplasts.

The objective of this study was to obtain pure prematurely condensed chromosomes (PCC) by a fusion between mitoplasts and interphase G1 cells. The stabilization of mitoplasts with spermine (25 microM) and a modification of the Sendai virus-mediated fusion enabled us to obtain pure PCC without contaminating mitotic chromosomes. This study clearly suggests that the factors for premature chromosome condensation induction are present in the cytoplasm of the mitotic cells. Pure PCC obtained by this method may help us to understand the nature of the factors initiating chromosome condensation and cell division.

G2 phase-specific proteins of HeLa cells.

The objective of this study was to determine if HeLa cells irreversibly arrested in G2 phase of the cell cycle by a brief exposure to a nitrosourea compound were deficient in certain proteins when compared with G2-synchronized cells. Total cellular proteins of G2-synchronized, G2-arrested, and S phase-synchronized cells were compared by two-dimensional polyacrylamide gel electrophoresis. The S phase cells differed from the G2-synchronized and G2-arrested cells by the absence of about 35 and 25 protein spots, respectively, of a total of nearly 150. At least nine protein spots in the molecular weight range of 4--5 X 10(4) that were present in the G2-synchronized cells were absent in both the G2-arrested and the S phase cells. Thus, these studies suggest that the missing proteins are probably necessary for the transition of cells from G2 phase to mitosis. Supplying the missing proteins to the G2-arrested cells by fusion with G2-synchronized cells facilitated the entry of the former into mitosis.