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Biomedical subjects

B Marin

Publications and source records attributed to B Marin.

At least 19 recordsLinked to original sources

[Gas in hepatic veins associated with tunneled femoral hemodialysis catheter].

We report the case of a female patient admitted for acute renal failure who required hemodialysis treatment using a tunneled femoral catheter. Abdominal ultrasound showed isolated gas in the hepatic veins. It was related to manipulation of the catheter, which allowed the passage of gas bubbles from the inferior vena cava into the hepatic veins.

Catheterization↗

Molecular phylogeny and taxonomic revision of Chlamydomonas (Chlorophyta). I. Emendation of Chlamydomonas Ehrenberg and Chloromonas Gobi, and description of Oogamochlamys gen. nov. and Lobochlamys gen. nov.

The genus Chlamydomonas (including Chloromonas) is one of the largest green algal genera comprising more than 600 species. To initiate a comprehensive analysis of the phylogeny and systematics of the genus, we determined nuclear-encoded SSU rRNA sequences from 32 strains of Chlamydomonas, Chloromonas and Chlorogonium with emphasis on oogamous taxa and related strains, and incorporated these into global molecular phylogenetic analyses of 132 strains of Chlorophyceae. In addition, we studied the morphology and reproduction of oogamous and related strains by light microscopy. We recognize and designate 18 monophyletic lineages (clades) within the Chlorophyceae, 11 of which are confined to the CW (basal bodies displaced clockwise) subgroup. The majority of clades recognized within the Chlorophyceae do not correspond to any of the traditional classification systems, which are still largely based on the organization level. Strains assigned to Chlamydomonas and Chloromonas were found in seven different clades confirming the polyphyly of the two genera as presently conceived. To initiate the taxonomic revision of Chlamydomonas, C. reinhardtii is proposed as the conserved type of the genus. In consequence, species in clades other than the clade containing C. reinhardtii must be transferred to other genera, a process initiated in this contribution. The oogamous strains studied represent a monophyletic lineage, which is described as Oogamochlamys gen. nov. comprising three species (O. gigantea, O. zimbabwiensis and O. ettlii spec. nov.). The sister clade to Oogamochlamys consists of isogamous strains characterized by chloroplasts with incisions and is described as Lobochlamys gen. nov. with two species (L. culleus and L. segnis). Another clade is characterized by asteroid or perforated, parietal chloroplasts and contains the type species of Chloromonas (C. reticulata). Thus, the polyphyletic Chloromonas (traditionally defined as "Chlamydomonas without pyrenoids") can be legitimized as a monophyletic genus by restriction to this clade and is here emended on the basis of chloroplast characters (the clade contains strains with or without pyrenoids thus rejecting the character "absence of pyrenoids").

Animals↗

Mesostigmatophyceae, a new class of streptophyte green algae revealed by SSU rRNA sequence comparisons.

Complete nuclear-encoded SSU rRNA sequences have been obtained from three taxa of streptophyte green algae (Klebsormidium nitens, Nitella capillaris, Chaetosphaeridium globosum) and two strains of the scaly green flagellate Mesostigma viride. Phylogenetic analyses of 70 taxa of Viridiplantae (Chlorophyta and Streptophyta) and 57 taxa of streptophyte green algae and embryophyte plants using distance, parsimony and likelihood methods revealed a novel monophyletic lineage among the Streptophyta comprising the genera Mesostigma and Chaetosphaeridium. This lineage is described here as the Mesostigmatophyceae classis nova. Our analyses demonstrate that (1) scaly green flagellates (prasinophytes) are polyphyletic, (2) a scaly green flagellate is a member of the Streptophyta and forms a clade with the oogamous, filamentous Chaetosphaeridium to the exclusion of all other known streptophyte green algae, (3) a previously published SSU rRNA sequence of Chaetosphaeridium (AF113506) is chimeric and contains part of a fungal SSU rRNA, and (4) the phylogenetic relationships between the Mesostigmatophyceae and other streptophyte green algae remain unresolved by SSU rRNA sequence comparisons.

Chlorophyta↗

Circadian rhythms of plasma corticosterone at different times after induction of diabetes. Responses to corticoadrenal stimulation in light and dark phases.

In this study we have tried to determine the effects of streptozotocin-induced (50 mg/kg) diabetes (15 and 30 day duration) on circadian rhythms of plasma corticosterone concentrations and on the responsiveness of the adrenal glands to exogenously administered ACTH at the time of maximum and minimum levels of plasma corticosterone. Rats were kept under controlled lighting 12h light/12h dark (12L/12D) and fed ad libitum. The corticosteroid circadian pattern in control (C) rats is characterized as one in which peak corticosterone concentrations occur at the beginning of the dark phase (activity period), with a decrease over the remainder of the 24h period. Circadian rhythmicity of plasma corticosterone concentration was absent in the diabetic rats 15 days after induction (D15 rats), with higher mean levels than the C. However, in the diabetic rats 30 days after induction (D30 rats) there is a recovery of this rhythm with similar acrophase and amplitude to the C rats. One hour after stimulation by ACTH (5 IU/kg) at the time of maximum and minimum levels of plasma corticosterone, the C rats showed similar plasma corticosterone levels. In the D15 rats, levels of corticosterone in the light phase one hour after ACTH administration were higher than in the dark phase; being lower than C in this phase. The loss of capacity to respond during the dark phase may be due to adrenal blunting in this phase with high levels of plasma corticosterone. In D30 rats, there is a more noticeable loss of capacity for adrenal response in the light than in the dark phase, with values lower than C and D15 rats in both phases. These findings suggest that the duration of diabetes has a significant role in both plasma corticosterone rhythms and adrenal sensitivity to ACTH administration.

Adrenocorticotropic Hormone↗

Prevalence and correlates of herpes simplex infections. The population-based AIDS in Multiethnic Neighborhoods Study.

OBJECTIVE: To examine the extent and correlates of infection with herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) in an inner-city community, we studied the prevalence of antibodies to these viruses and their association with risk behaviors in a representative sample of unmarried white, black, and Hispanic adults living in San Francisco, Calif. DESIGN: Cross-sectional, community-based, random household survey. PARTICIPANTS: In 1988 and 1989, we surveyed 1770 unmarried men and women aged 20 to 44 years from three San Francisco neighborhoods of varying geographic and cultural characteristics. MAIN OUTCOME MEASURES: HSV-1 and HSV-2 antibodies based on an immunodot assay using type-specific glycoproteins gG-1 and gG-2. RESULTS: Of blood samples from 1212 participants available for testing, 750 (62%) had HSV-1 antibodies and 400 (33%) had HSV-2 antibodies. After controlling for other variables, HSV-1 antibody was significantly correlated (P less than .05) with older age (in heterosexual men, women, and homosexually active men), less education (in heterosexual men and women), and Hispanic (especially those not born in the United States) or black race. HSV-2 antibody was significantly correlated (P less than .05) with female gender, number of lifetime sexual partners and older age (in heterosexual men and women), and low levels of education and black or Hispanic race (in women). Among those with antibody to HSV-2, only 28 (19%) of 149 men and 32 (13%) of 251 women reported a history of genital herpes. However, most men (62%) and women (84%) who reported a history of genital herpes had HSV-2 antibodies. We observed a similar pattern (low sensitivity and moderate specificity) for a history of facial herpes and the presence of HSV-1 antibodies. After controlling for other variables, HSV-2 antibodies were associated with a lower frequency of HSV-1 antibodies among homosexual men infected with the human immunodeficiency virus. CONCLUSIONS: HSV-1 antibodies were found in nearly two thirds of single urban adults and were most common among Hispanics not born in the United States. HSV-2 antibodies were found in one third of this population and were associated with risk behaviors for sexually transmitted diseases. For both facial and genital herpes infections, self-reporting of infection was very insensitive and moderately specific.

Adult↗

Condom use in multi-ethnic neighborhoods of San Francisco: the population-based AMEN (AIDS in Multi-Ethnic Neighborhoods) Study.

We examined the prevalence and correlates of condom use in a community-based sample of unmarried heterosexual and gay/bisexual Whites, Blacks, and Hispanics (aged 20 to 44 years) in San Francisco (n = 1229). Only 9% of heterosexual males reported always using condoms, and fewer of those with multiple sexual partners (6%) reported always using condoms compared with those in monogamous relationships (12%). Much higher proportions of gay/bisexual men reported always using condoms (48%). Racial differences in condom use were observed only among women. Sexual communication and the sexual enjoyment value of condoms were consistent correlates of condom use across gender and sexual orientation, while other condom-related beliefs were significant predictors of condom use only for men. In general, condom promotion programs should build sexual communication skills, teach people how to enhance enjoyment with condoms, and reduce psychological barriers to condom acquisition and use.

Adult↗

Risk for AIDS in multiethnic neighborhoods in San Francisco, California. The population-based AMEN Study.

To examine the actual and potential spread of human immunodeficiency virus (HIV) from an acquired immunodeficiency syndrome (AIDS) epicenter to surrounding neighborhoods, we studied the prevalence of the viral infection and AIDS risk behaviors from 1988 to 1989 in a representative sample of unmarried whites, African Americans, and Hispanics living in San Francisco. We surveyed 1,770 single men and women aged 20 to 44 years (a 64% response rate) in a random household sample drawn from 3 neighborhoods of varying geographic and cultural proximity to the Castro District where the San Francisco epidemic began. Of 1,369 with blood tests, 69 (5%) had HIV antibodies; all but 5 of these reported either homosexual activity (32% HIV-positive; 95% confidence interval [CI] = 23%, 41%), injection drug use (5% HIV-positive; CI = 1%, 14%), or both (59% HIV-positive; CI 42%, 74%). Homosexual activity was more common among white men than among African-American or Hispanic men, but the proportion of those infected was similar in the 3 races. Both the prevalence of homosexually active men and the proportion infected were much lower in the 2 more outlying neighborhoods. Risk behaviors in the past year for acquiring HIV heterosexually--sex with an HIV-infected person or homosexually active man or injection drug user, unprotected sexual intercourse with more than 4 partners, and (as a proxy) having a sexually transmitted disease--were assessed in 1,573 neighborhood residents who were themselves neither homosexually active men nor injection drug users. The prevalence of reporting at least 1 of these risk behaviors was 12% overall, and race-gender estimates ranged from 5% among Hispanic women to 21% among white women. We conclude that in San Francisco, infection with HIV is rare among people who are neither homosexually active nor injection drug users, but the potential for the use spread of infection is substantial, as 12% of this group reported important risk behaviors for acquiring the virus heterosexually.

Acquired Immunodeficiency Syndrome↗

Effect of alcohol treatment on sexual behaviour of male rats.

The effect of chronic alcohol treatment on sexual parameters of the male rats was studied. The results showed that the ingestion of cognac leads to significant alterations in the sexual behaviour of the male rat. Sexual parameters indicated that sexual behaviour is drastically affected by cognac consumption. The parameters affected were the number of ejaculation; initial latency, ejaculation latencies and neuromotor activities which showed significant variation (P less than 0.01). Further, mounts without, with and total intromissions and refractory periods were significantly affected by alcohol consumption. In addition, the percentage of tests during which an ejaculation was observed was significantly reduced (P less than 0.01) in the alcohol-treated males when compared with control groups.

Animals↗

Insulin stimulation of water intake in humans.

Drinking response to the intravenous administration of insulin (0.1 U/kg) was studied in 15 volunteers (eight males and seven females). Water intake was significantly higher after insulin than after saline administration during the 90-min period studied. Plasma glucose decreased significantly in individuals receiving insulin and the time of the maximum decrease (30 min) was concurrent with the beginning of water intake. Haematocrit values in the insulin-treated group were also significantly higher at that time. Plasma renin activity (PRA) after insulin administration was higher than under basal conditions or after saline injection. On the other hand, psychological responses indicated that insulin probably elicits thirst prior to the hunger which appears with hypoglycaemia. A possible role of endogenous insulin in meal-related thirst is hypothesized.

Adult↗

Islet transplantation restores normal serum amylase levels in diabetic rats.

Diabetes is associated with a diminution in exocrine pancreatic function. The goal of our study was to investigate whether the altered exocrine pancreatic function of streptozotocin-induced diabetic rats could be ameliorated by islet transplantation. Diabetic rats received either more than 1,000 syngeneic islets intraportally (islet transplantation group) or pancreatic, nonviable insular tissue (sham transplantation group). Plasma amylase and insulin levels in diabetic rats were significantly lower than in normal rats. The exocrine pancreas of streptozotocin-induced diabetic rats showed alterations (decrease of zymogen granules, diminution of endoplasmic reticulum, clusters of ribosomes without organization) in the structure of acinar cells at the electron microscopic level. After islet transplantation, plasma glucose levels were restored to normal values, and those of amylase and insulin gradually increased to normal values. A positive correlation between plasma levels of amylase and insulin was found. Three months after islet transplantation, the islet-transplanted rats did not show morphologic alterations of the acinar cells which were still found in the sham-transplanted rats. It is concluded that alterations of exocrine pancreas in streptozotocin-induced diabetic rats are ameliorated by islet transplantation.

Amylases↗

Effects of inhibitors of the renin-angiotensin system on water intake after insulin administration.

Male wistar rats drank in a dose-related manner, in response to 1 to 40 U/kg of i.p. insulin. Maximum intakes took place during the first 30 min after i.p. insulin administration, coinciding with the period of maximal drop of blood glucose. Plasma renin activity (PRA) in rats treated with i.p. insulin was higher than in basal conditions or after saline injection. Nephrectomy and adrenalectomy did not abolish insulin-induced drinking. A low dose of captopril (0.1 mg/kg s.c.) did not modify insulin-induced drinking, but a higher dose (10 mg/kg s.c.), or enalapril (0.5 mg/microgram s.c.), significantly increased insulin-induced drinking. Enhancement of insulin-induced drinking by s.c. captopril was not secondary to an increased diuresis. Captopril (50 micrograms i.c.v.) significantly reduced the cumulative water intake after i.p. insulin (20 U/kg i.p.) plus s.c. captopril (10 mg/kg). The blockade of central receptors for angiotensin II with sarile-AII (5 micrograms) significantly diminished insulin-induced drinking. It appears that the peripheral renin angiotensin system is not necessary for insulin-induced drinking but central angiotensin II plays an important role.

1-Sarcosine-8-Isoleucine Angiotensin II↗

Reproductive function and sexual behaviour in female rats exposed to immobilization stress or ACTH injections during gestation.

Pregnant primiparous rats were exposed to low immobilization stress or ACTH injections (one unit) throughout pregnancy. We measured the following parameters in the female offsprings: puberty (vaginal opening and first oestrous), oestrous cycle and sexual behaviour. Compared to the controls, female sexual receptivity measured by means of lordosis and the lordosis quotient (LQ) increased in both the experimental groups, but the puberty parameters of the offspring did not alter.

Adrenocorticotropic Hormone↗

Plasma corticosterone, motor activity and metabolic circadian patterns in streptozotocin-induced diabetic rats.

Experiments were conducted in male rats to study the effects of streptozotocin-induced diabetes on circadian rhythms of (a) plasma corticosterone concentrations; (b) motor activity; and (c) metabolic patterns. Animals were entrained to LD cycles of 12:12 hr and fed ad libitum. A daily rhythm of plasma corticosterone concentrations was found in controls animals with peak levels at 2400 hr and low values during the remaining hours. This rhythm was statistically confirmed by the cosinor method and had an amplitude of 3.37 micrograms/100 ml and the acrophase at 100 hr. A loss of the normal circadian variation was observed in diabetic animals, with a nadir at the onset of light period and high values throughout the remaining hours; cosinor analysis of these data showed no circadian rhythm, delete and a higher mean level than controls. As expected, normal rats presented most of their motor activity during the dark period with 80% of total daily activity; the cosinor method demonstrated a circadian rhythm with an amplitude of 60% of the mean level and the acrophase at 0852 hr. Both diabetic and control rats showed a similar activity during the light phase, but diabetic animals had less activity than controls during the night and their percentage of total daily activity was similar in both phases of the LD cycle (50% for each one). With the cosinor method we were able to show the persistence of a circadian rhythm in the motor activity of diabetic rats, but with a mesor and amplitude lower than in controls (amplitude rested at 60% of the mean level) and its acrophase advanced to 0148 hr.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

[Reflex pressure response to the electric stimulation of different parts of the rat stomach].

The role of the autonomic nervous system in the pressor response to the electrical stimulation of different gastric zones has been studied in rats. The stimulus was applied before and after the following interventions: bilateral vagotomy, ganglionic blockade, alpha-adrenergic receptor blockade and beta-adrenergic receptor blockade. After the ganglionic blockade no pressor responses to the electrical stimulus were observed. After the alpha-adrenergic blockade a lower pressor response was observed. A hypertensive response can be induced by mechanical, chemical or electrical stimulation of gastric receptors. It is concluded that the pressor reflex following the application of an electrical stimulus on different zones of the digestive tract is mediated by the sympathetic nervous system and that the efferent pathways are mainly alpha-adrenergic ones.

Adrenergic alpha-Antagonists↗

Reflex pressor response to gastric mechanical stimulation in rats.

Neural and humoral mechanisms involved in the reflex pressor response during mechanical stimulation of the stomach of rats were investigated. The arterial blood pressure response was prevented by inhibition of alpha-adrenergic vasoconstriction using either an alpha-adrenergic blocker or a ganglionic blocker. In addition, there was a small decrease in the response after nephrectomy. However, there were no alterations in the response after beta-adrenergic blockade, bilateral adrenalectomy, inhibition of converting enzyme activity with enalapril or bilateral cervical vagus nerve transection. The heart rate was not modified after either intervention. After vagotomy the time of recovery of the basal blood pressure was significantly prolonged. It can be concluded that the blood pressure response to mechanical stimulation of the stomach wall is of neural rather than of humoral origin and mainly involves activation of alpha-adrenergic receptors. Vagal efferent pathways could be also involved.

Adrenalectomy↗