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Biomedical subjects

A G Ross

Publications and source records attributed to A G Ross.

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

Dissolution of gallstones with simvastatin, an HMG CoA reductase inhibitor.

The aim of this study was to determine whether 12 months of therapy with Simvastatin, an HMG CoA reductase inhibitor, would dissolve gallstones. Twenty-seven subjects entered the study, all had a fasting oral cholecystogram, ultrasound examination, and fasting serum lipids prior to therapy. In addition, 22 subjects had their gallbladder ejection fraction, after CCK, determined by radionucleotide scanning. Eleven subjects had the cholesterol saturation index (CSI) of bile calculated before and at the end of 12 months of therapy. Of the 27 subjects, 26 completed 12 months of treatment with Simvastatin 20 mg daily. There was a significant fall in the total serum cholesterol (27%, P < 0.0001), LDL cholesterol (31%, P < 0.0001), triglyceride (34%, P < 0.0001) but no change in HDL after 12 months of therapy. Simvastatin treatment resulted in a 28% fall in the CSI of bile at the end of therapy (P < 0.01). The concentrations of individual bile acids did not change with therapy, and apart from a slight but significant increase in arachidonate, there were no other significant changes in the fatty acid composition of the biliary phospholipids. After 12 months of Simvastatin therapy there was a small decrease in the gallstone diameter but complete dissolution of gallstones was not achieved in any subjects. In conclusion 12 months of therapy with Simvastatin was effective in lowering the serum lipids and the CSI of bile but was not effective in dissolving gallstones.

Adult↗
PubMed1998

Differential antigen-stimulated proliferation of human mononuclear cells by recombinant Schistosoma japonicum antigens in a Chinese population.

Peripheral blood mononuclear cells (PBMC) from 117 individuals living on two islands in an area (Dongting Lake) endemic for schistosomiasis japonica in China, and 15 control individuals from a non-endemic area of China, were assessed for antigen-stimulated proliferation against five recombinant Schistosoma japonicum antigens of recognized interest in the development of immunity to schistosomiasis. Two recombinant antigens, paramyosin and 28-kD glutathione-S-transferase, stimulated cellular proliferation (stimulation index > or = 3.0) in 38.5% and 42.5% of subjects, respectively, a level similar to that induced by a soluble whole parasite extract (51.3%). In contrast, three other recombinant antigens tested--a fatty acid binding protein, 22-kD tegumental membrane-associated antigen, and glyceraldehyde-3-phosphate dehydrogenase--stimulated PBMC proliferation in only 3-8% of subjects. Moreover, we also identified a positive association between the degree of exposure, and cellular proliferation following stimulation with recombinant paramyosin or whole parasite extract. Highly significant differences in antigen-stimulated proliferation were also observed between the two islands, Niangashan and Qingshan. The whole parasite extract stimulated proliferation in 90% of subjects from Niangashan island compared with only 42.1% of subjects from Qingshan island (chi2 = 16.88, P = 0.00004), while glutathione-S-transferase stimulated proliferation in 77.3% of subjects from Niangashan island compared with only 34.7% of subjects from Qingshan island (chi2 = 13.09, P = 0.003). A similar, but not significant, trend was observed for paramyosin and the fatty-acid binding protein. The identification of differential cellular proliferative responses to specific schistosome antigens within an infected human population may have important practical implications for vaccine development against schistosomiasis japonica.

Adult↗
PubMed1998

Five year impact of chemotherapy on morbidity attributable to Schistosoma japonicum infection in the Dongting Lake region.

OBJECTIVE: To determine changes in the last 5 years of the fraction of acute and chronic symptoms attributable to schistosomiasis japonica in fishing communities with moderate endemicity in the Dongting Lake region of China. METHOD: Complete medical histories, physical examinations, and stool samples were obtained from 1909 individuals (53% male) ranging in age from 4 to 81 years. Age, sex, occupation, frequency of water contact, number of times treated for schistosomiasis, and last year of treatment were tested as potential effect modifiers and confounders. RESULTS: Overall, there were very few infected cases and very little variation in any prevalence ratio with infection intensity, sex, age, year of last treatment, number of times treated or frequency of water contact. The attributable fraction of liver enlargement in one village was estimated at 0.114 (11.4%), although this was not significantly > 0(95% CI; -0.008-0.237). CONCLUSION: The chemotherapy-based schistosomiasis control programme in this locality has succeeded in reducing attributable morbidity to undetectable levels, but many uncertainties remain about sustaining control efforts in the future. Both old and new control strategies will have to be examined if the health and well-being of these people are to be maintained into the next millennium, given that periodic chemotherapy will not be accepted indefinitely.

Adolescent↗
PubMed1998

Epidemiological identification of Chinese individuals putatively susceptible or insusceptible to Schistosoma japonicum: a prelude to immunogenetic study of human resistance to Asian schistosomiasis.

An epidemiological method, field-tested in Hunan, China, to identify residents potentially susceptible or insusceptible to endemic schistosomiasis japonica is described, as a prelude to selection of subjects for immunogenetic studies. After an initial cross-sectional survey on two islands (Qingshan and Niangashan--population 2990) in 1995-1996, an informative cohort (N = 249) was selected for treatment and 9-month follow-up to measure exposure and re-infection. Both the population prevalence (15.8%) and the geometric mean intensity of infection (26.2 eggs/g faces) indicated that the islands were moderately endemic for schistosomiasis. Exposure measurements revealed a strong, positive, linear association (r = 0.70) between daily activity diaries and direct water-contact observation. Individuals identified as stool-positive for schistosomiasis had significantly more water contact than those who were egg-negative (P = 0.03). Almost all (93%) of the cohort had ultrasonographic evidence of periportal fibrosis before treatment but in only 1.2% was this fibrosis scored > 1 in terms of the stages identified by the World Health Organization. At the follow-up it was possible to classify the 249 subjects into three, distinct, exposure-infection epidemiological groups. The first group (N = 20) was susceptible to re-infection and constituted 8% of the cohort. The second group (N = 61) was apparently insusceptible to re-infection despite the continuing high levels of exposure and included 24% of the cohort. The other 68% of the cohort (N = 168) remained uninfected but were at most only moderately exposed, or had a status indeterminate due to non-compliance. This epidemiological identification of susceptibles and insusceptibles for schistosomiasis japonica' links field and ongoing laboratory studies aimed at characterising the genetic and immunological factors associated with resistance to re-infection and/or disease.

Adolescent↗
PubMed1997

An examination of current control strategies for Asian schistosomiasis in the Dongting lake region of China. II. A five year follow-up survey on Qingshan island.

In 1995-1996 we conducted an epidemiological survey in two communities (1656 individuals) on Qingshan island, Hunan province P.R. China, in order to determine the efficacy of current control strategies since their upgrading in 1991. In 1996, the overall prevalence for Schistosoma japonicum, Ascaris lumbricoides, Ancylostoma duodenale, and Trichuris trichiura had decreased moderately since 1991. The age-specific prevalence for S. japonicum for each of the representative age groups decreased slightly, but there was a significant reduction in these prevalences for the 5-9 (P < 0.01), 55-59 (P < 0.05) and the over 60 (P < 0.01) age groups. The 1996 intensities of infection for schistosomiasis were higher for all the age categories except for those aged 0-4 and 25-29 years of age. When the study population was further classified according to the percent uninfected, lightly infected (8-100 eggs/g (epg)), moderately infected (101-400 epg) and heavily infected (> 400 epg) for S. japonicum, there were fewer (5.6%) people infected in 1996 but the proportions of moderately (21.3 vs. 15.5%) and heavily (7.6 vs. 2.3%) infected individuals were higher than those observed in 1991. The reported cases of weakness and hepatomegaly (MSL > or = 3) were significantly lower (P < 0.01) in 1996 for both uninfected and infected (all intensities) individuals. General episodes of diarrhoea were also significantly lower in 1996 for those lightly (P < 0.05) and heavily (P < 0.01) infected. Likewise, the occurrence of splenomegaly (Hackett's > or = 2) was significantly lower among uninfected (P < 0.01) and heavily infected (P < 0.05) patients. In summary, although significant progress has been made in controlling schistosomiasis and other helminth infections in this highly endemic focus for schistosomiasis, there is still room for improvement. Chemotherapy for bovines and humans, mollusciding for Oncomelania control and health education should be initiated and upgraded if the health and well being of these island communities is to further improve.

Adolescent↗
PubMed1997

An evaluation of Schistosoma japonicum infections in three villages in the Dongting lake region of China. I. Prevalence, intensity and morbidity before the implementation of adequate control strategies.

We examined three Chinese villages (one farming village and two fishing villages) in an area highly endemic for schistosomiasis japonica in order to study the prevalence, intensity of infection and the associated morbidities before the implementation of adequate control strategies. Socio-economic status, medical histories including the frequency and type of water contact, physical examinations, parasitological examinations and questionnaires relevant to the knowledge of schistosomiasis were performed on a random sample of 1542 individuals (45% female; 55% male). The prevalence of Schistosoma japonicum was 9.4% in the farming village and 16.5 and 26.2% in the fishing villages. Eighty-three percent of the infected population had light infections (8-100 eggs per gram stool (epg)) and only 6% had heavy infections (> 400 epg). Both the prevalence and intensity of infection varied significantly (P < 0.01) with the frequency of water contact. All the morbidity indicators (weakness, inability to work, diarrhoea, hepatomegaly and splenomegaly) were significantly higher (P < 0.01) among those infected with S. japonicum. Knowledge of schistosomiasis, in general, was unsatisfactory in all three villages; 12.4% of the population was infected when their knowledge of schistosomiasis was good, whereas 26.6% of the population was infected when their knowledge was poor. Further, it appears that schistosomiasis control based on selective chemotherapy (praziquantel) of randomly selected stool-positive individuals was ineffective in significantly reducing the prevalence of S. japonicum and its associated clinical manifestations in the villages under study.

Adolescent↗
PubMed1997

Schistosomiasis control in the People's Republic of China.

Schistosomes, snail-transmitted trematodes (blood flukes), cause a major parasitic disease that ranks second only to malaria in terms of human suffering in the tropics. Schistosoma japonicum has occupied its ecological niche in China for thousands of years; through natural selection it has evolved survival mechanisms that make it difficult (if not impossible) to eradicate. As discussed here by Allen Ross, Li Yuesheng, Adrian Sleigh and Don McManus, vaccination, in combination with current control strategies, may significantly reduce the morbidity of this disease and ultimately improve the quality of life for those living adjacent to endemic zones. This article provides a special focus in Hunan province and examines the potential impact of the Three Gorges Super Dam Project on schistosomiasis control.

Journal Article↗
PubMed1997

Epidemiologic features of Schistosoma japonicum among fishermen and other occupational groups in the Dongting Lake region (Hunan Province) of China.

In this study we examined 1,909 individuals (53% males and 47% females) to determine the current status of Schistosoma japonicum among the people in five fishing villages situated on two islands (large, Qingshan island; small, Niangashan island) in the Dongting Lake region in Hunan Province, the People's Republic of China. The results of this study indicate that the overall prevalence for schistosomiasis on the two islands is 16%. Two distinct peaks in prevalence (29%) were observed at 25-35 years of age and again at 45-55 years of age for both the large and small islands. On the small island the overall prevalence (24%) varied significantly (P < 0.01) from the large island (15%). Fishermen had the highest prevalence (22.4%) among all the occupational groups examined but students produced the highest worm intensity (geometric mean = 69 eggs per gram [epg] of feces). There was a significant difference (P < 0.01) in the prevalence of schistosomiasis between males and females. In general, males had a much higher prevalence (22%) than females (8.9%). When the study populations were classified as uninfected, lightly infected (10-100 epg), moderately infected (101-400 epg), and heavily infected (> 401 epg) with S. japonicum, the distribution pattern was similar for each of the five villages. The majority (76-88%) of the population remains uninfected. Lightly infected individuals had the highest prevalence (7-12%) followed by moderately infected individuals (1-9%). Only a very small percentage of the population was heavily infected (0-2%). Hepatomegaly along the midsternal line (MSL > or = 3) was commonly seen in both uninfected (21%) and infected individuals (1939%). Subjects heavily infected with S. japonicum reported significantly higher (P < 0.05) cases of liver enlargement when compared with those uninfected. The reported cases of abdominal pain for both uninfected (9%) and infected individuals (4-19%) was relatively high. Lightly and moderately infected individuals reported significantly (P < 0.05 and P < 0.01, respectively) more episodes of abdominal pain than those uninfected. The occurrence of diarrhea was low (5%) for uninfected individuals but this clinical feature was significantly (P < 0.01) more prevalent in both the lightly and heavily infected categories (8-17%).

Adolescent↗
PubMed1996

Evaluation of alpha interferon for the treatment of chronic hepatitis B infection in Christchurch.

AIM: To evaluate alpha interferon for the treatment of chronic replicative hepatitis B infection in Christchurch patients. METHODS: Ten patients were divided into two groups depending upon whether their average pretreatment ALT levels were greater than twice the upper limit of normal (group 1, 6 subjects) or less than twice the upper limit of normal (group 2, 4 subjects). Interferon alpha-2a (4.5 mega units) was administered three times a week for 24 weeks with the addition of a preceding priming course of prednisone in group 2. RESULTS: At 6 months post treatment only one patient in group 1 had seroconverted (HBeAg to anti-HBe), however, the remaining five patients seroconverted from 18-32 months after therapy. This response was associated with normalisation of the transaminases and in 5/6 subjects a fall in the HBV DNA levels. In group 2 one subject seroconverted by 6 months despite a shortened course of Interferon. A delayed seroconversion (18 months) was observed in one patient and another had a partial response with the development of anti-HBe but associated with persistence of HBeAg. The remaining patient has not responded. CONCLUSIONS: Interferon alpha-2a was effective in promoting a seroconversion HBeAg to anti-HBe in patients with chronic hepatitis B and transaminases elevated to twice the upper limit of normal, although in most cases this response was delayed. Larger studies will be required to determine the role of steroid priming in those with less active disease.

Adult↗
PubMed1996

Differences between observed and predicted energy costs at rest and during exercise in three subsistence-level populations.

Estimates of daily energy expenditure are important for many areas of research in human ecology and adaptability. The most common technique for estimating human energy expenditure under field conditions, the factorial method, generally relies on activity-specific energy costs derived from published sources, based largely on North American and European subjects. There is concern that such data may not be appropriate for non-Western populations because of differences in metabolic costs. The present study addresses this concern by comparing measured vs. predicted energy costs at rest and during sub-maximal exercise in 83 subjects (52 males, 31 females) from three subsistence-level populations (Siberian herders and highland and coastal Ecuadorian farmers). Energy costs at rest (i.e., lying, sitting and standing) and while performing a standard stepping exercise did not significantly differ among the three groups. However, resting energy costs were significantly elevated over predicted levels (+ 16% in men, + 11% in women), whereas exercising costs were comparable to predicted values (-6% in men, + 3% in women). Elevations in resting energy needs appear to reflect responses to thermal stress. These results indicate that temperature adjustments of resting energy costs are critical for accurately predicting daily energy needs among traditionally living populations.

Adaptation, Physiological↗
PubMed1995

Treatment of chronic hepatitis C with interferon alpha.

AIM: To evaluate the response to interferon alpha in patients with chronic hepatitis C in Christchurch. METHOD: Fifteen patients with chronic HCV were given interferon alpha 3 million units subcutaneously three times a week for up to 24 weeks. A complete and partial biochemical response was defined by relative changes in the serum alanine aminotransferase (ALT) during the treatment period. Detection of HCV RNA by the polymerase chain reaction was used to determine the virological response to treatment. RESULT: A complete or partial response was seen in nine of the 15 patients (60%). Histological improvement was demonstrated in all patients for whom paired liver biopsies were taken. Following treatment two of the five complete responders have shown a sustained biochemical response but only one has remained PCR negative, ie, a sustained virological responder. The other three, complete responders and all four partial responders relapsed. CONCLUSION: The response to treatment and relapse was comparable with other studies. It remains to be shown whether investigation of the viral titre and/or viral type will help to explain the high relapse rate in these patients with chronic HCV.

Adult↗
PubMed1995

Comparison of the heart rate-monitoring and factorial methods: assessment of energy expenditure in highland and coastal Ecuadoreans.

Accurate estimates of total daily energy expenditure (TDEE) are critical to studies of the nutritional adaptation of human populations. This study compared the standard factorial method with the recently developed flex-HR technique in a sample of 32 adults (16 males, 16 females) from rural, agricultural communities of highland and coastal Ecuador. Although energy expenditures obtained from the two methods were highly correlated (r = 0.759, P < 0.0001), the 1985 FAO/WHO/UNU factorial method significantly underestimated TDEE relative to the heart rate-monitoring technique (10.27 +/- 2.54 compared with 11.91 +/- 3.96 MJ/d, P < 0.001). The degree of underestimation was greater in males, who had higher energy expenditures. Similarly, underestimation was greater in the highland farmers, who were studied during a period of heavy agricultural work. The differences in energy expenditure estimates translated into a 10% difference in estimated energy adequacy. Additional research is needed to identify the potential sources of bias in the factorial method and to further develop other techniques for accurately estimating energy expenditure under field conditions.

Adolescent↗
PubMed1994

Towards a shorter calving interval in South African dairy herds.

The effects of a progestagen treatment regimen on the calving-to-conception period and number of inseminations per conception in a Holstein-Friesland herd [n = 60] were investigated. No significant (P > 0.05) differences were observed in days from calving to conception (80.5 vs. 82.3) and inseminations per conception (1.52 vs. 1.41) between the treatment and the control groups, although the treatment possibly contributed to an improved oestrus detection rate.

Anestrus↗
PubMed1990

Preferential over-expression of the class alpha rat Ya2 glutathione S-transferase subunit in livers bearing aflatoxin-induced pre-neoplastic nodules. Comparison of the primary structures of Ya1 and Ya2 with cloned class alpha glutathione S-transferase cDNA sequences.

Normal rat liver expresses Ya (Mr 25,500), Yc (Mr 27,500) and Yk (Mr 25,000) Class Alpha glutathione S-transferase (GST) subunits. The Ya-type subunit can be resolved into two separate polypeptides, designated Ya1 and Ya2, by reverse-phase h.p.l.c. In rat livers that possess aflatoxin B1-induced pre-neoplastic nodules, a marked increase is observed in the expression of Ya1, Ya2, Yc and Yk; of these subunits, Ya2 exhibited the greatest increase in concentration. The Ya1 and Ya2 subunits isolated from nodule-bearing livers were cleaved with CNBr, and the purified peptides were subjected to automated amino-acid-sequence analysis. Differences in the primary structures of the two Ya GST subunits were found at positions 31, 34, 107 and 117. These data demonstrate that Ya1 and Ya2 are distinct polypeptides and are the products of separate genes. The amino acid sequences obtained from Ya1 and Ya2 were compared with the cloned cDNAs pGTB 38 [Pickett, Telakowski-Hopkins, Ding, Argenbright & Lu (1984) J. Biol. Chem. 259, 4112-4115] and pGTR 261 [Lai, Li, Weiss, Reddy & Tu (1984) J. Biol. Chem. 259, 5182-5188], which encode rat Ya-type subunits. From these comparisons it appears probable that Ya1 represents the GST subunit encoded by pGTR 261, whereas Ya2 represents the subunit encoded by pGTB 38. It is likely that the over-expression of Ya1 and Ya2 in nodule-bearing livers is of major significance in the acquired resistance of nodules to aflatoxin B1, since previous work [Coles, Meyer, Ketterer, Stanton & Garner (1985) Carcinogenesis 6, 693-697] has shown that the Ya-type GST subunit has high activity towards aflatoxin B1 8,9-epoxide.

Aflatoxins↗
PubMed1987

The psychological impact of diagnostic ultrasound.

The psychological impact of ultrasound scanning in pregnancy was examined in low- and high-risk pregnancies. Women in each category were assigned consecutively to a condition of either low or high feedback. In the latter condition, the women received extensive verbal and visual feedback, whereas in the former, subjects were denied visual access to the monitor. Psychological changes were measured using the State Anxiety Inventory and the Subjective Stress Scale. When a male partner attended, he was included in the assessment. The emotional impact of ultrasound was influenced by the level of feedback provided, with those in the high-feedback condition indicating significantly less anxiety and more positive emotional experiences during the scan, compared with those who received less feedback.

Adult↗
PubMedDate not supplied

Two-year impact of praziquantel treatment for Schistosoma japonicum infection in China: re-infection, subclinical disease and fibrosis marker measurements.

We studied a community cohort of 193 individuals exposed to endemic Schistosoma japonicum infection in the Dongting Lake region of China to assess subclinical morbidity and the 2-year benefit of curative therapy (praziquantel) administered in 1996. Prevalence and intensity of S. japonicum infection before treatment were 28% and 192 eggs per gram faeces (epg), respectively. Two years after cure, 22% of the cohort were re-infected, but with a lighter intensity (67 epg). Sixty-four subjects (37%) showed significant improvement in ultrasound parenchyma images after treatment and 51 subjects (54%) showed significant improvement of periportal fibrosis. Left-lobe enlargement also reversed (P < 0.05) and splenomegaly reversed in 6 of 8 cases and developed in only 1. Two years post-treatment a dilated portal vein became less frequent, but the decline was not significant (16% vs 11%, P < 0.05). The serum levels of laminin and collagen IV associated with re-infection and intensity and hyaluronic acid levels correlated with ultrasound findings (P < 0.01). Overall, treatment induced a marked decrease in subclinical hepatosplenic morbidity attributable to S. japonicum although low-intensity re-infection after treatment remained relatively frequent. Stratified analysis and logistic models evaluated potential confounding factors for assessment of treatment effects on hepatic fibrosis. S. japonicum infection and moderate-heavy alcohol intake interacted: improvement in parenchymal morbidity was impeded among drinkers (P < 0.05). Chemotherapy focused on at-risk residents controls prevalent subclinical hepatic fibrosis but re-infection indicates the need for complementary control strategies.

Adolescent↗