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Biomedical subjects

N Luo

Publications and source records attributed to N Luo.

At least 37 records · Page 2Linked to original sources
PubMed1998

Epidemiology of rotavirus diarrhoea in Africa: a review to assess the need for rotavirus immunization.

Rapid progress towards the development of rotavirus vaccines has prompted a reassessment of the disease burden of rotavirus diarrhoea in developing countries and the possible impact of these vaccines in reducing diarrhoeal morbidity and mortality among infants and young children. We examined the epidemiology and disease burden of rotavirus diarrhoea among hospitalized and clinic patients in African countries through a review of 43 published studies of the etiology of diarrhoea. The studies were carried out from 1975 through 1992, and only those in which a sample of more than 100 patients with diarrhoea were specifically screened for rotavirus by using an established diagnostic test were included. Rotavirus was detected in a median of 24% of children hospitalized for diarrhoea and in 23% who were treated as outpatients; 38% of the hospitalized patients with rotavirus were < 6 months and 81% were < 1 year of age. Rotavirus was detected year-round in nearly every country and generally exhibited distinct seasonal peaks during the dry months. In 5 countries where rotavirus strains had been G-typed, 74% of strains were of one of the four common serotypes (G1 to G4), G1 was the predominant serotype, and 26% were non-typeable. This cumulative experience from 15 African countries suggests that rotavirus is the most important cause of severe diarrhoea in African children and that most strains in circulation today belong to common G types that are included in reassortant vaccines. Wherever large numbers of cases of rotavirus diarrhoea occur early in infancy, immunization at birth may protect the children before their first symptomatic infection.

Africa↗
PubMed1997

Geographical distribution of HIV-1 group O viruses in Africa.

OBJECTIVE: To determine to what extent HIV-1 group O strains are present in different African countries. MATERIALS AND METHODS: A total of 14,682 samples of sera from a range of patients from 12 different African countries were tested. All the sera were tested with an enzyme-linked immunosorbent assay (ELISA) using a combination of V3 peptides from ANT-70 and MVP-5180. Samples reactive in ELISA were retested in a line immunoassay (LIA-O). Samples reactive in ELISA were also retested with an in-house Western blot to determine the presence of antibodies to gp120 of HIV-1 ANT-70. Polymerase chain reaction was performed on HIV-1 group O and group O indeterminate sera. RESULTS: Of all the sera samples tested, only 19 sera had antibodies to group O V3 peptides exclusively and 46 were indeterminate for group O infection in LIA-O. The highest prevalence of HIV-1 group O infection among HIV-positive sera was observed in Cameroon (2.1%) and neighbouring countries, 1.1% in Nigeria and 0.9% in Gabon. The lowest rates were seen in west Africa: 0.07% in Senegal, 0.14% in Togo, 0.16% in Chad and 0.3% in Niger. Group O sera were observed in almost all the population categories tested. The ANT-70 V3 peptide in LIA-O was reactive with all of the sera considered to be HIV-1 group O antibody positive by LIA, versus 78.9% for the MVP-5180 peptide. Thirteen out of 19 group O samples of sera were tested in PCR. Eight samples were identified as group O by specific group O pol and/or V3 primers; in the remaining five samples no HIV RNA could be detected. Of the indeterminate sera samples, two were identified as group O. CONCLUSION: In eight of the 12 countries tested, antibodies to group O viruses were identified. Numbers of HIV-1 group O viruses are low. Their presence is not restricted to Cameroon and neighbouring countries but can also be found in west and south-east Africa.

Africa↗
PubMed1997

Neopterin, beta 2-microglobulin, and acute phase proteins in HIV-1-seropositive and -seronegative Zambian patients with tuberculosis.

Neopterin is a biochemical marker for the activation of the cell-mediated immune system. We measured neopterin, beta 2-microglobulin, and acute phase proteins in 31 HIV-seropositive and -seronegative Zambian patients with tuberculosis, using stored sera that had been obtained at the beginning and at end of antituberculosis treatment. In both HIV-seropositive and -seronegative patients neopterin and acute phase proteins were elevated when tuberculosis was initially diagnosed and fell during treatment. In contrast, the mean beta 2-microglobulin level increased during antituberculous therapy in the HIV-seropositive group. Serum neopterin levels at diagnosis were correlated with other parameters of disease activity (fever, anemia, and weight loss). In both groups, patients with persistently elevated neopterin levels at the end of treatment were more likely to suffer relapse of tuberculosis or other adverse health events in the subsequent follow-up period. Neopterin can be used to monitor the response to antituberculous therapy in both HIV-seropositive and -seronegative patients and may have a prognostic value for the patients' wellbeing in the follow-up period.

AIDS-Related Opportunistic Infections↗
PubMed1997

[Determination of amoxicillin in human plasma by high performance liquid chromatography and its pharmacokinetics].

A rapid and sensitive assay for amoxicillin in human plasma has been developed using reversed phase high performance liquid chromatography. Plasma samples were prepared for analysis by addition of internal standard (tinidazole) followed by protein precipitation with HClO4. A YWG C18H37 column as stationary phase and a 0.033 mol.L-1 phosphate buffer (pH 7.2)--methanol mixture (85:15) as mobile phase were used with the UV detector set at 229 nm. The calibration curve was linear in the range from 0.2 microgram.ml-1 to 20.0 micrograms.ml-1 with gamma > 0.999. The analytical recovery of amoxicillin from plasma was > 86.7%. The relative standard deviations for within-day and between-day were < 5.48% and < 8.29%, respectively. Following oral administration of 500 mg in human volunteers, the peak levels of amoxicillin in plasma averaged 6.88 +/- 2.25 micrograms.ml-1 at 84.4 +/- 21.1 min. The mean half life time for amoxicillin was 62.8 +/- 14.6 min.

Adult↗
PubMed1997

[HPLC determination of diltiazem in human serum and its pharmacokinetic parameters].

A simple and sensitive reversed-phase liquid chromatographic method has been developed and validated for the analysis of diltiazem in human serum and the study of pharmacokinetics of the drug in human body. Diltiazem and diazepam (internal standard) in serum were extracted with hexane-chloroform-isopropanol (60:40:5, V/V), and then measured by HPLC using a Spherisorb C18 column as stationary phase and a methanol-water triethylamine as mobile phase. Diltiazem was quantified by ultraviolet absorbance at 239 nm. The method proved to be linear in the clinical range of 15-300 microg/L with a regression coefficient of 0.9997. The lower limit of detection of diltiazem in serum was 3 microg/L. Intra-day and inter-day coefficients of variation of assay for diltiazem in serum were 3.5%-6.8% (n=7) and 6.2%-8.4% (n=5), respectively. The recoveries of diltiazem were 91%-104% for serum. The method has been used to determine diltiazem in serum samples from eight volunteers and provided data on the pharmacokinetics of the drug. The results inferred that diltiazem is absorbed rapidly and had a relatively short half-life time in healthy individuals. The data obtained was fitted with PKBP-N1 program on computer to study the pharmacokinetics. The results showed that the peak level in serum averaged 118.5 microg/L +/- 14.3 microg/L at 3.1 h +/- 0.4 h, and the areas under the drug concentration curves (AUC) was 793.1 microg x h/L +/- 83.1 microg x h/L.

Antihypertensive Agents↗
PubMed1996

Importance of human immunodeficiency virus-associated lymphadenopathy and tuberculous lymphadenitis in patients undergoing lymph node biopsy in Zambia.

The relative importance of human immunodeficiency virus (HIV)-associated lymphadenopathy amongst patients presenting for lymph node biopsy in Central Africa is unknown. HIV-1 serology and histology of patients undergoing superficial lymph node biopsy during 1989-1990 in Lusaka, Zambia, were examined in a prospective cohort study of HIV serology and by retrospective review of laboratory records. Of 727 lymph nodes biopsied in Lusaka in 1989-1990, 380 (52 per cent) showed tuberculous lymphadenitis, 160 (22 per cent) histology suggestive of primary HIV lymphadenopathy and 66 (9 per cent) nodal Kaposi's disease. HIV serology was tested in 280 adults and was positive in 91 per cent (255 patients), including 89 per cent (153 of 171) of those with tuberculous lymphadenitis, 98 per cent (63 of 64) of those with histology suspicious of primary HIV lymphadenopathy and all (24 of 24) with nodal Kaposi's disease. Other HIV-associated lymphadenopathy included nodal lymphomas and lymphoepithelial cysts. HIV serology was tested in 22 children and was positive in eight, including four of 14 with tuberculous lymphadenitis. It is concluded that HIV-associated lymphadenopathy, especially tuberculous lymphadenitis, is very common amongst patients presenting for lymph node biopsy in Central Africa.

AIDS-Related Complex↗
PubMed1996

The prevalence and aetiology of persistent diarrhoea in adults in urban Zambia.

As the AIDS pandemic has spread, diarrhoea in adults has become a major burden on health care institutions in central Africa and on the families of sufferers. In order to assess the magnitude of the problem, we carried out a survey of households in a high population density township of Lusaka to determine the prevalence of persistent diarrhoea in adults. We also carried out a study of the causes of persistent diarrhoea in patients attending the University Teaching Hospital, Lusaka. The community survey assessed 460 households, representing a sample of 1440 adults. 94 adults were reported as having had diarrhoea in the 2 weeks prior to the survey, implying an attack rate of 1.74 per adult per year. Of these 94 cases, six had diarrhoea of between 2 and 4 weeks duration, and ten had diarrhoea of over 4 weeks duration. In the hospital study, 75 (97%) out of 77 patients with diarrhoea of over 1 months' duration were HIV seropositive; potentially pathogenic parasites were found in 61/75 (81%) of seropositives. This information indicates that persistent diarrhoea in adults, mostly related to HIV infection, is likely to be an important and growing reservoir of enteric pathogens and represents a significant burden on hospitals and relatives. This emerging problem in sub-Saharan Africa may foreshadow developments in other continents.

Adult↗
PubMed1996

The increased burden of tuberculous lymphadenitis in central Africa: lymph node biopsies in Lusaka, Zambia, 1981 and and 1990.

In order to assess the effect of the HIV epidemic on lymph node biopsies in Central Africa, HIV-1 serology was tested on a cohort of patients undergoing node biopsy in Lusaka in 1990, and the histology of all lymph nodes biopsied in Lusaka in 1981 and 1990 was reviewed. One hundred and eighteen lymph nodes were biopsied in 1981 and 351 in 1990. Cases of tuberculous lymphadenitis increased from 52 (31 children and 21 adults) in 1981 to 186 (22 children, 160 adults, four patients unknown age) in 1990. Sixty-eight of 77 adults (88%) with tuberculous lymphadenitis in 1990 tested HIV-positive. Cases of histology suspicious of primary HIV lymphadenopathy and nodal Kaposi's disease also increased. Cases of malignant lymphadenopathy and overall number of surgical biopsies remained equivalent for 1981 and 1990. The study concludes that the HIV epidemic has led to a large increase in diagnostic lymph node biopsies in Lusaka, mostly through an increase in HIV-related adult tuberculous lymphadenitis.

AIDS-Related Complex↗
PubMed1996

[Effects of high dose pulse oral calcitriol on secondary hyperparathyroidism in patients with end-stage renal disease].

To evaluate the therapeutic effects of high dose pulse oral calcitrol, 3.5 micrograms calcitrol three times a week and calcium carbonate were administered to 13 patients with end-stage renal disease on chronic hemodialysis with hyperparathyroidism refractory to conventional calcitrol therapy. Serum parathyroid hormone and osteocalcin were detected by radioimmunoassay. Serum parathyroid hormone level of the patients decreased from 1111 +/- 344 ng/L to 492 +/- 218 ng/L by 57.5 +/- 11.5 percent (P < 0.01) in 6 months after the beginning of treatment. Both serum alkaline phosphatase and osteocalcin levels declined markedly, and correlated positively with that of parathyroid hormone. Plasma calcium concentration was markedly elevated, but no obvious increase of plasma phosphate was found. High dose pulse oral calcitrol was effective on secondary hyperparathyroidism. During the course of treatment timely and individual adjustment of calcitrol dose and dialysate calcium concentration is essential.

Administration, Oral↗
PubMed1995

Rotavirus gastro-enteritis in hospitalized children with acute diarrhoea in Zambia.

The clinical and epidemiological aspects of rotavirus diarrhoea were studied in hospitalized children with acute diarrhoea in Lusaka, Zambia. Two hundred and fifty-six (24.0%) of 1069 children admitted to the study were shedding rotavirus. The rotavirus-positive rate was highest in children less than 1 year of age (37.0%) and it was also high in those less than 6 months old. Rotavirus diarrhoea was seen throughout the year with a higher rotavirus-positive rate in the dry season. In rotavirus-positive diarrhoea patients, more children were dehydrated (82.4%) than in the rotavirus-negative group (56.2%). Rotavirus infection was more common in the children with normal nutritional status (27.6%, 162/588) than in those with malnutrition (19.3%, 93/482). The associated case fatality rate in the rotavirus-positive group was 6.4%, significantly less than in the rotavirus-negative group (OR 0.44, 95% CI 0.24-0.79), and mortality cases were seen only in children less than 2 years old.

Acute Disease↗
PubMed1995

HEp-2 cell-adherent Escherichia coli in patients with human immunodeficiency virus-associated diarrhea.

Diarrhea occurs commonly in African human immunodeficiency virus (HIV) infections. A case-control (HIV-positive vs. -negative) study of adults with diarrhea was done in Lusaka, Zambia, to determine the prevalence of intestinal infection by HEp-2 cell-adherent Escherichia coli. Adherent E. coli were more common in HIV-positive patients with acute diarrhea than among HIV-negative controls (60% vs. 33%) and were found significantly more often in HIV-positive patients with chronic diarrhea than among HIV-negative controls with chronic diarrhea (79% vs. 17%, P < .002). Adherent strains were found significantly more often among HIV-positive patients (69%) than in 22 asymptomatic subjects (36%, P < .02). The HEp-2 cell adherence of the E. coli strains did not show a common pattern. Adherent bacteria were also observed in colonic biopsies from 32% of Zambians with chronic diarrhea who underwent endoscopy. Adherent E. coli may be an important cause of HIV-associated diarrhea in Zambia.

Acute Disease↗
PubMed1995

Use of saliva as an alternative to serum for HIV screening in Africa.

Saliva has been recommended as a safe and effective alternative to serum for enzyme-linked immunosorbent assay (ELISA) for HIV antibodies in surveillance programmes in developing countries. We evaluated the use of saliva specimens for detection of HIV antibodies using three different commercially available ELISAs. Saliva specimens from 107 patients selected at random from HIV high-risk (38), medium-risk (27) and low-risk (42) areas of the hospital were screened with the Wellcozyme HIV1 + 2 GACELISA VK61 (recommended for use with saliva), Wellcozyme HIV1 + 2 VK54/55 and Wellcozyme HIV-1 recombinant VK56/57. Of the 107 patients, 50 were positive and 57 negative for antibodies to HIV on confirmatory Western blot testing. For detection of antibodies to HIV in saliva, the Wellcozyme HIV1 + 2 GACELISA VK61 had a sensitivity and a specificity of 98%, the Wellcozyme HIV-1 recombinant VK56/57 a sensitivity and specificity of 96%, and the Wellcozyme HIV1 + 2 VK54/55 a sensitivity of 94% and a specificity of 95%. For detection of antibodies to HIV in serum, the Wellcozyme HIV-1 recombinant VK56/57 had a sensitivity and a specificity of 100%, the Wellcozyme HIV1 + 2 GACELISA VK61 a sensitivity and a specificity of 98%, and the Wellcozyme HIV1 + 2 VK54/55 a sensitivity and a specificity of 96%. This study illustrates that saliva can be used as an alternative to serum for screening for anti-HIV antibodies in African patients.

Developing Countries↗
PubMed1995

The impact of human immunodeficiency virus on response to treatment and recurrence rate in patients treated for tuberculosis: two-year follow-up of a cohort in Lusaka, Zambia.

To examine the effect of HIV on response to treatment and recurrence rate in patients with tuberculosis (TB), we have followed 239 previously untreated, adult, TB patients in a prospective cohort study in Lusaka, Zambia. One hundred and seventy-four (73%) were HIV-1 antibody positive. Patients with sputum smear positive, miliary, or meningeal TB were prescribed 2 months daily streptomycin, thiacetazone, isoniazid, rifampicin, pyrazinamide followed by 6 months thiacetazone and isoniazid; others, 2 months streptomycin, thiacetazone and isoniazid followed by 10 months thiacetazone and isoniazid. Thirty-five per cent of HIV-positive (HIV+ve) and 9% of HIV-negative (HIV-ve) patients were known to have died before the scheduled end of treatment. Surviving HIV+ve patients showed weight gain and improvement in symptoms and laboratory and radiological findings similar to HIV-ve patients. The risk of cutaneous drug reaction was 17% (95% CI: 12-25%) in HIV+ve, and 4% (1-13%) in HIV-ve patients. Severe rashes were attributed to thiacetazone. Recurrence of active TB was examined among 64 HIV+ve and 37 HIV-ve patients who successfully completed treatment, with mean follow-up after the end of treatment of 13.5 and 16.8 months, respectively. The rate of recurrence was 22/100 person years (pyr) for HIV+ve patients and 6/100 pyr for HIV-ve patients, giving a recurrence rate ratio of 4.0 (95% CI 1.2-13.8, P = 0.03).

AIDS-Related Opportunistic Infections↗
PubMed1995

Hepatitis B virus infection among pregnant women in Zambia.

The prevalence of hepatitis B virus (HBV) markers was studied in pregnant women attending antenatal clinics in Zambia. A total of 2,098 pregnant women were recruited into the study at three urban health centres in Lusaka, the capital city and four district hospitals in rural areas of different provinces of Zambia. The overall prevalence of HBsAg was 6.5% (137/2,098), and HBeAg was present in 16.1% (22/137) of those positive for HBsAg. Antibody positive rate (HBsAb and/or HBcAb) was 51.3% in randomly selected HBsAg negative samples. HBsAg positive rate varied between 3.3% and 13.6% in each study sites. Prevalence for both HBsAg and antibodies to HBV were significantly higher in rural areas (district hospitals) than in urban areas (urban health centres in Lusaka). These data show that although HBV is endemic in Zambia, the prevalence varies from region to region.

Adult↗
PubMed1994

Intestinal secretory IgA immune response against human immunodeficiency virus among infected patients with acute and chronic diarrhea.

Diarrhea is common in patients infected with the human immunodeficiency virus (HIV) in Africa. There has been speculation that HIV itself may cause some of the enteropathy seen. The intestinal secretory IgA (sIgA) response was used to evaluate HIV intestinal infections in Zambian patients with acute and chronic diarrhea. sIgA was extracted from stool specimens and evaluated by an ELISA. Seven (58%) of 12 HIV-positive patients with acute diarrhea and 25 (69%) of 36 HIV-positive patients with chronic diarrhea showed an sIgA response to HIV p24, compared with 1 of 10 HIV-positive patients without diarrhea (P < .025 for acute and P < .001 for chronic diarrhea). The mean duration of diarrhea was significantly longer in patients showing an anti-p24 response. An sIgA response to HIV antigens occurs commonly in infected patients with diarrhea and may provide further evidence of an etiologic role of HIV in the diarrhea associated with AIDS.

Acute Disease↗