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Biomedical subjects

M Ravera

Publications and source records attributed to M Ravera.

At least 37 records · Page 2Linked to original sources
PubMed1996

Randomized study of antibiotic prophylaxis for general and gynaecological surgery from a single centre in rural Africa.

In a district rural hospital in Uganda, 850 surgical patients were evaluated prospectively over a 3-year period to compare the clinical efficacy of conventional postoperative penicillin therapy with single-dose ampicillin prophylaxis for hernia repair and ectopic pregnancy, and with single-dose ampicillin-metronidazole prophylaxis for hysterectomy and caesarean section. The high rate of postoperative infection usually encountered in African hospitals after conventional treatment with penicillin for 7 days was significantly reduced with the new regimen: from 7.5 to 0 per cent in hernia repair and from 10.7 to 2.4 per cent in ectopic pregnancy; from 20.0 to 3.4 per cent in hysterectomy and from 38.2 to 15.2 per cent in caesarean section. Length of hospital stay and postoperative mortality rates were also significantly reduced. Single-dose ampicillin prophylaxis with or without metronidazole, although rarely used in developing countries, is more cost effective than standard penicillin treatment.

Adolescent↗
PubMed1996

The deletion polymorphism of the angiotensin I-converting enzyme gene is associated with target organ damage in essential hypertension.

The activity of the renin-angiotensin-aldosterone system is thought to play a significant role in the development of target organ damage in essential hypertension. An insertion/deletion (I/D) polymorphism of the angiotensin I-converting enzyme (ACE) gene has recently been associated with increased risk for left ventricular hypertrophy and coronary heart disease in the general population. The D allele is associated with higher levels of circulating ACE and therefore may predispose to cardiovascular damage. The study presented here was performed to investigate the association between the ACE genotype, microalbuminuria, retinopathy, and left ventricular hypertrophy in 106 patients with essential hypertension. ACE gene polymorphism was determined by polymerase chain reaction technique. Microalbuminuria was evaluated as albumin-to-creatinine ratio (A/C) in three nonconsecutive first morning urine samples (negative urine culture) after a 4-wk washout period. Microalbuminuria was defined as A/C between 2.38 to 19 (men) and 2.96 to 20 (women). Hypertensive retinopathy was evaluated by direct funduscopic examination (keith-Wagener-Barker classification) and left ventricular hypertrophy by M-B mode echocardiography. The distribution of the DD, ID, and II genotypes was 27, 50, and 23%, respectively. The prevalence of microalbuminuria, retinopathy, and left ventricular hypertrophy was 19, 74, and 72% respectively. There were no differences among the three genotypes for age, known duration of disease, body mass index, blood pressure, serum glucose, uric acid, and lipid profile. DD and ID genotypes were significantly associated with the presence of microalbuminuria (odds ratio, 8.51; 95% confidence interval, 1.07 to 67.85; P = 0.019), retinopathy (odds ratio, 5.19; 95% confidence interval, 1.71 to 15.75; P = 0.005) and left ventricular hypertrophy (odds ratio, 5.22; 95% confidence interval, 1.52 to 17.94; P = 0.016). Furthermore, patients with DD and ID genotypes showed higher levels of A/C (3.6 +/- 0.9, DD; 2.6 +/- 0.7, ID; 0.9 +/- 0.2 mg/mmol, II; P = 0.0015 by analysis of variance) and increased left ventricular mass index (152 +/- 4.7, DD + ID versus 133 +/- 5.7 g/m2, II; P = 0.01) compared with II patients. The D allele was significantly more frequent in patients with microalbuminuria (odds ratio, 2.59; 95% confidence interval, 1.24 to 5.41; P = 0.013) and in those with retinopathy (odds ratio, 2.44; 95% confidence interval, 1.21 to 4.90; P = 0.015). Multiple regression analyses performed among the entire cohort of patients demonstrated that ACE genotype significantly and independently influences the presence of retinopathy, left ventricular hypertrophy, and microalbuminuria. In conclusion, the D allele of the ACE gene is associated with microalbuminuria as well as with retinopathy and left ventricular hypertrophy, and seems to be an independent risk factor for target organ damage in essential hypertension.

Adult↗
PubMed1996

Clinical and endoscopic aspects of hepatosplenic schistosomiasis in Uganda.

INTRODUCTION: Hepatosplenic schistosomiasis is characterized by hepatic periportal fibrosis (Symmers' fibrosis), portal venous obstruction that leads to portal hypertension and its complications, and splenomegaly. Demonstration of pathological lesions due to Schistosoma mansoni can be achieved by using different techniques but because of its sensitivity, specificity and simplicity, ultrasound has replaced wedge biopsy of the liver as the gold standard for detecting schistosomal periportal fibrosis. The aims of the study were to evaluate clinical aspects of schistosomiasis in a well defined area and to assess whether there was a relationship between the grade of periportal fibrosis and the presence of oesophageal varices and their features. MATERIALS AND METHODS: A total of 122 patients with proven schistosome infection were enrolled in the study. Each underwent ultrasound examination to assess hepatosplenic involvement and staging, and upper digestive endoscopy to assess the presence of oesophageal varices and their features. For all the patients, the main characteristics and symptoms, possibly related to schistosomiasis, were also recorded. RESULTS: A close relationship was found between the grade of periportal fibrosis and the presence of oesophageal varices, their grade and localization in the oesophagus. There was also was a relationship between haematemesis and size of varix, localization of varix and presence of cherry-red spots, but no correlation was found with other endoscopic features of varices. CONCLUSION: Clinical aspects of schistosomiasis in Hoima District are similar to what is known from the literature and there are no specific features. The study shows that ultrasonography is an important tool for accurate staging of hepatosplenic schistosomiasis. Although it cannot replace endoscopy, it can direct the need for performing it. In fact, the higher the grade of periportal fibrosis the greater the possibility of having oesophageal varices. Endoscopy is of value in detecting oesophageal varices especially in advanced stages of liver schistosomiasis, in describing their endoscopic features so as to detect those more at risk of bleeding, and for emergency sclerotherapy.

Adult↗
PubMed1995

Prevalence of micro- and macroalbuminuria and their relationship with other cardiovascular risk factors in essential hypertension.

A cohort of 227 untreated essential hypertensive patients from north-western Italy was studied in order to evaluate the prevalence of micro- and macroalbuminuria and their relationship with other cardiovascular risk factors. Albuminuria was evaluated as the albumin to creatinine ratio (Alb/Cr) in three non-consecutive first morning samples. The prevalence of microalbuminuria and macroalbuminuria was 10% and 2.2%, respectively. Albuminuric patients showed higher blood pressure, serum creatinine, triglycerides and uric acid as well as a greater prevalence of retinopathy. Stepwise multiple regression analysis demonstrated that only a small part of variations in albuminuria was explained by changes in blood pressure. Duration of disease did not seem to influence microalbuminuria. The presence of hypertensive retinopathy was associated with greater albuminuria, longer duration of hypertension, and higher prevalence of major ECG changes, but not with higher blood pressure levels. Microalbuminuria, rather than a consequence of elevated blood pressure levels, seems to be a marker of a syndrome featuring, among other characteristics, essential hypertension. Furthermore, microalbuminuria must be considered as an independent cardiovascular risk factor.

Adolescent↗
PubMed1995

A study of breastfeeding and the return of menses in Hoima District, Uganda.

The effect of breastfeeding on reestablishment of ovulation and fertility and on birth spacing are now well known. A study was conducted on lactational amenorrhoea (LAM) at 180 days in Hoima District, Uganda in order to understand whether and how LAM could be applied in fertility control and birth spacing. Since the introduction of supplementary food by Ugandan women does not replace or substitute for breastfeeding, a study was designed to determine if LAM was effective irrespective of supplementation of infant's diet. One hundred and fifty four mother/child pairs were entered into the study and 134 women completed the sixth month of the study. At the end of the period, eighty four women (62.7%) were amenorrhoeic of whom only 33 (39.3%) were exclusively breastfeeding and no woman had dropped out of the study because of pregnancy or the use of other family planning methods other than LAM. The study confirmed that LAM could be applicable in Uganda to the majority of the breastfeeding women (62.7%). It is expected that if health workers increase the intensity of breastfeeding support as well as the women's knowledge and motivation to use LAM for family planning, this would contribute to children's health as well as to birth spacing that is one of the major factors related to infant deaths. According to data from this study, the return of menses is irrespective of whether supplements have been introduced and their frequency.

Adolescent↗
PubMed1994

Kaposi's sarcoma and AIDS in Uganda: its frequency and gastrointestinal distribution.

The frequency and distribution of gastrointestinal Kaposi's sarcoma were investigated in 63 consecutive AIDS patients. The main risk factor for AIDS was heterosexual intercourse. Gastrointestinal lesions were found in 24 cases (38.1%): 12 patients (11.1%) had both upper and lower GI tract involvement, 7 patients (11.1%) had only oesophago-gastroduodenal lesions and 5 (7.9%) only lower tract disease. Our results show that in heterosexual Africans, the tumours closely resemble the tumours of western homosexuals in endoscopic appearance, in being multicentric and in the gastro-intestinal tract involved. We conclude that even in the heterosexual African AIDS population, the gastrointestinal tract is frequently involved and this phenomenon, if more widely studied might give us new elements about the aetiophatogenesis of Kaposi's sarcoma which is still unclear.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Cloning of three human tyrosine phosphatases reveals a multigene family of receptor-linked protein-tyrosine-phosphatases expressed in brain.

A human brainstem cDNA library in bacteriophage lambda gt11 was screened under conditions of reduced hybridization stringency with a leukocyte common antigen (LCA) probe that spanned both conserved cytoplasmic domains. cDNA encoding a receptor-linked protein-tyrosine-phosphatase (protein-tyrosine-phosphate phosphohydrolase, EC 3.1.3.48), RPTPase alpha, has been cloned and sequenced. Human RPTPase alpha consists of 802 amino acids. The extracellular domain of 150 residues includes a hydrophobic signal peptide and eight potential N-glycosylation sites. This is followed by a transmembrane region and two tandemly repeated conserved domains characteristic of all RPTPases identified thus far. The gene for RPTPase alpha has been localized to human chromosome region 20pter-20q12 by analysis of its segregation pattern in rodent-human somatic cell hybrids. Northern blot analysis revealed the presence of two major transcripts of 4.3 and 6.3 kilobases. In addition to RPTPase alpha, two other RPTPases (beta and gamma), identified in the same screen, have been partially cloned and sequenced. Analysis of sequence comparisons among LCA, the LCA-related protein LAR, and RPTPases alpha, beta, and gamma reveals the existence of a multigene family encoding different RPTPases, each containing a distinct extracellular domain, a single hydrophobic transmembrane region, and two tandemly repeated conserved cytoplasmic domains.

Amino Acid Sequence↗
PubMed1990

Possible dissociation of the heparin-binding and mitogenic activities of heparin-binding (acidic fibroblast) growth factor-1 from its receptor-binding activities by site-directed mutagenesis of a single lysine residue.

The fibroblast or heparin-binding growth factors (HBGFs) are thought to be modulators of cell growth and migration, angiogenesis, wound repair, neurite extension, and mesoderm induction. A better understanding of the structural basis for the different activities of these proteins should facilitate the development of agonists and antagonists of specific HBGF activities and identification of the signal transduction pathways involved in the mechanisms of action of these growth factors. Chemical modification studies of Harper and Lobb (Harper, J. W., and R. R. Lobb. 1988. Biochemistry. 27:671-678) implicated lysine 132 in HBGF-1 (acidic fibroblast growth factor) as being important to the heparin-binding, receptor-binding, and mitogenic activities of the protein. We changed lysine 132 to a glutamic acid residue by site-directed mutagenesis of the human cDNA and expressed the mutant protein in Escherichia coli to obtain sufficient quantities for functional studies. Replacement of this lysine with glutamic acid reduces the apparent affinity of HBGF-1 for immobilized heparin (elutes at 0.45 M NaCl vs. 1.1 M NaCl for wild-type). Mitogenic assays established two points: (a) human recombinant HBGF-1 is highly dependent on the presence of heparin for optimal mitogenic activity, and (b) the change of lysine 132 to glutamic acid drastically reduces the specific mitogenic activity of HBGF-1. The poor mitogenic activity of the mutant protein does not appear to be due to a reduced affinity for the HBGF receptor. Similarly, the mutant HBGF-1 can stimulate tyrosine kinase activity and induce protooncogene expression. Differences in the biological properties of the wild-type and mutant proteins were observed in transfection studies. Mutant HBGF-1 expression in transfected NIH 3T3 cells did not induce the same transformed phenotype characteristic of cells expressing wild-type HBGF-1. Together these data indicate that different functional properties of HBGF-1 may be dissociated at the structural level.

Animals↗
PubMed1977

Long-term administration of DDT or phenobarbital-Na in Wistar rats.

In lifespan studies, outbred male and female Wistar rats were given either technical DDT mixed into the diet at a dose of 500 parts per million (ppm) or phenobarbital-sodium dissolved in drinking water at a dose of 500 ppm. Liver-cell tumors developed in treated animals but not in controls. The incidence of liver tumors was 45% in the DDT-treated group and 44% in the phenobarbital-sodium-group. When evaluated by sex, DDT-treated females and males had incidences of 56% and 35%, respectively, while in the phenobarbital-sodium group, the respective incidences were 32% and 59% in females and males. These data show a varying susceptibility between the sexes, with regard to induction of liver-cell tumors by the two compounds. In both treated groups, the number of nodular tumors per rat and the average size increased with age and were greater in females. None of these tumors and metastasized. Histologically, the liver tumors were nodular growths, which compressed surrounding parenchyma did not infiltrate it. The total incidence of extrahepatic tumors was higher in controls than in treated animals. In this connection, we must mention the apparent, but not significant, reduction of adrenal tumors in treated rats compared to the controls.

Age Factors↗