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Biomedical subjects

T M Davis

Publications and source records attributed to T M Davis.

At least 19 recordsLinked to original sources
PubMed2001

Parasitic procrastination: late-presenting ovale malaria and schistosomiasis.

A 29-year-old woman with ovale malaria (most likely contracted, together with asymptomatic schistosomiasis, in East Africa two years previously) had fever, nausea and confusion, jaundice, anaemia, thrombocytopenia, hyponatraemia and hypokalaemia. She was initially diagnosed with and treated for blood-smear-positive vivax malaria. Because of the unusual clinical presentation, blood was analysed by a malaria species-specific nested polymerase chain reaction (PCR) assay which identified Plasmodium ovale as the only infecting species. This case illustrates (i) that a detailed travel history remains a vital part of clinical assessment, (ii) ovale malaria can have an exceptionally long incubation period and features of a moderately severe acute infection, and (iii) PCR assay may prove a valuable adjunct to blood film examination in the diagnosis and speciation of malaria.

Adult↗
PubMed2001

A heterocyclic inhibitor of the REV-RRE complex binds to RRE as a dimer.

As part of a search for organic compounds that selectively target RNA, we found that specific diphenylfuran derivatives, which are related to compounds that bind to the DNA minor groove, bind very strongly to RNA in a manner very sensitive to the structure of the compounds. In extended development of the diphenylfuran series, we found that a tetracationic heterocycle containing a phenyl-furan-benzimidazole unfused aromatic system, DB340, exhibits pronounced selectivity for the RRE RNA stem-loop from HIV-1. We report here RNA footprinting, spectroscopic analysis, affinity determinations, and initial NMR structural results of the complex. The results indicate that DB340 binds to RRE in a highly structured and cooperative complex at a 2:1 DB340 to RRE ratio. Overlap in the NMR spectra prevents detailed description of binding interactions at this time, but we are able to place DB340 in the RNA minor groove. Additionally, footprinting results and studies with mutant RRE sequences indicate that the internal loop of RRE is required for specific binding of DB340 as with the Rev protein. These results provide exciting new ideas for rational drug design with RNA as is now common with DNA and proteins.

Amino Acid Sequence↗
PubMed2001

Effect of insulin therapy on quality of life in Type 2 diabetes mellitus: The Fremantle Diabetes Study.

Previous studies investigating the relationship between insulin therapy on quality of life (QOL) in Type 2 diabetes have produced conflicting results that may reflect differences in patient samples, study design and context. To assess the effect of insulin on QOL in a community-based, prospective and observational setting, we studied 1290 Type 2 patients recruited from a region of 120,097 people and undergoing detailed annual assessments of metabolic control and complications. The average age of the cohort was 64.1 years, the median duration of diabetes was 4.4 years and 48.9% were males. A modified Diabetes Quality of Life (DQOL) questionnaire and a health measurement questionnaire providing the Rosser index were administered annually. At baseline, the 149 insulin-treated patients had greater satisfaction, worry, impact and total DQOL scores (indicating a worse QOL) than the 1141 non-insulin-treated patients (P< or =0.018). Except in the case of satisfaction, these differences persisted after adjustment for potentially confounding demographic, socioeconomic and diabetes-specific variables (P<0.001). The Rosser index showed a similar pattern, with insulin-treated patients having lower values both before (P=0.012) and after (P<0.001) adjustment. During follow-up, 38 patients commenced insulin but there were no significant differences in DQOL scores or the Rosser index either side of this therapeutic change. In 389 patients on stable therapy and followed for 4 years, DQOL remained significantly higher in insulin-treated patients (P< or =0.005). These findings suggest that, although positive factors including increased support and improved hyperglycaemic symptoms may initially offset unfavourable aspects of insulin self-administration, their effect wanes and a lower QOL supervenes after 1-2 years.

Aged↗
PubMed2001

Dementia and its associations in type 2 diabetes mellitus: the Fremantle Diabetes Study.

BACKGROUND: recent studies indicate that diabetes is an important risk factor for dementia in older patients, but the cause remains unknown. OBJECTIVES: to determine whether vascular or diabetes-related risk factors predict the development of dementia in older subjects with diabetes. PATIENTS: 63 patients with type 2 diabetes of mean age 75.3 years. METHODS: Subjects were screened for cognitive impairment using the Mini-Mental State Examination (MMSE) and informants who knew the subjects answered the Informant Questionnaire for Cognitive Decline in the Elderly (IQCODE). Probable dementia was diagnosed using highly specific criteria based on the combination of both tests. Potential risk factors for dementia obtained at the time of the cognitive test and annually from a median of 3.2 years previously were examined using univariate methods and simple general linear modelling. RESULTS: since there was a significant association between MMSE and English speaking ability, ten non-Anglo-Celt patients were excluded from the analysis. Probable dementia was diagnosed in six of the remaining 53 subjects (11%). Dementia was significantly and independently associated with higher diastolic and mean arterial blood pressure measurements over the 3 years before assessment. Blood pressure declined over this time in the patients with probable dementia and was similar to that in non-demented subjects at the time of cognitive assessment. CONCLUSIONS: these preliminary data suggest that the high rate of dementia found in older people with diabetes may be explained by the high rate of hypertension in this population.

Aged↗
PubMed2001

Inhibition of the HIV-1 rev-RRE complex formation by unfused aromatic cations.

RNA viruses cause a wide range of human diseases. Development of new agents to target such viruses is an active area of research. Towards this goal, a series of diphenylfuran cations as potential inhibitors of the Rev-RRE complex have been designed and synthesized. Analysis of the interaction of the diphenylfurans with RRE and TAR RNA model systems by gel shift assays indicates that they exhibit both sequence and structure-dependent binding modes. Our results show a strong interaction between the diphenylfuran ring system and RRE bases, while the TAR interactions are much weaker with the compounds that are the best inhibitors of Rev-RRE.

Aminoglycosides↗
PubMed2001

Binge drinking among female Veterans Affairs patients: prevalence and associated risks.

This study evaluated the prevalence and associated risks of binge drinking, defined as having > or = 4 drinks on an occasion in the past year, in a female patient population. Of 1,259 female Veterans Affairs patients surveyed, 780 reported drinking alcohol in the past year, and 305 (24% of respondents, 39% of drinkers) reported binge drinking in the past year; 84 (11% of drinkers) had done so monthly or more often. Age-adjusted logistic regression analyses indicated that women who reported past-year binge drinking monthly or more often reported significantly increased odds of morning drinking (odds ratio [OR] = 40.3), others worrying about their drinking (OR = 38.6), arguments after drinking (OR = 13.5), hepatitis or cirrhosis (OR = 3.1), frequent injuries (OR = 2.6), smoking (OR = 3.7), drug use (OR = 22.2), and multiple sexual partners (OR = 4.6).

Adult↗
PubMed2001

The relationship between metformin therapy and the fasting plasma lactate in type 2 diabetes: The Fremantle Diabetes Study.

AIMS: To determine (i) which factors, including metformin, are associated with the fasting plasma lactate concentration in type 2 diabetes, and (ii) whether plasma lactate is associated with haemodynamic and metabolic effects. METHODS: We measured fasting plasma lactate in 272 well-characterized diabetic patients from a community-based sample, 181 (67%) of whom were taking metformin with or without other therapies. Linear regression analysis was used to identify predictors, including metformin therapy, of the plasma lactate, and to investigate associations between plasma lactate and resting pulse rate and serum bicarbonate. Factor analysis assessed independent relationships between groups of cosegregating variables. RESULTS: Metformin-treated patients had higher plasma lactate concentrations than nonmetformin-treated subjects (geometric mean [s.d. range] 1.86 [1.34-2.59] vs 1.58 [1.09-2.30] mmol x l(-1), respectively; P < 0.001). In a linear regression model, plasma glucose, BMI and metformin use (but not dose) were independently associated with plasma lactate (P < or = 0.028); after adjustment for the former two variables, metformin-treated patients had a mean plasma lactate 0.16 mmol l-1 greater than in subjects not taking the drug. Factor analysis revealed that plasma lactate, plasma glucose, BMI and pulse rate cosegregated but serum bicarbonate was not in this grouping. CONCLUSIONS: The present results show that metformin therapy increases the fasting plasma lactate in ambulant patients with type 2 diabetes from a community-based cohort. From associations in the data we hypothesize that this increase reflects (i) increased sympathetic activity in patients with the metabolic syndrome (ii) increased substrate (glucose) availability and (iii) a direct metformin effect.

Aged↗
PubMed2001

Multiple dose study of interactions between artesunate and artemisinin in healthy volunteers.

AIMS: To investigate whether coadministration of the antimalarials artesunate and artemisinin alters the clearance of either drug. METHODS: Ten healthy Vietnamese males (Group AS) were randomized to receive a single dose of 100 mg oral artesunate (pro-drug of dihydroartemisinin) on day -5 and then once daily for 5 consecutive days (days 1-5). Oral artemisinin (500 mg) was coadministered on days 1 and 5. Another 10 subjects (Group AM) were given 500 mg oral artemisinin on day -5 and then further doses on days 1-5. Artesunate 100 mg was given on days 1 and 5. Artemisinin and dihydroartemisinin plasma concentrations on days -5, 1 and 5 were quantified by h.p.l.c. with on-line postcolumn derivatization and u.v. detection. RESULTS: In Group AS, dihydroartemisinin oral clearance values (mean (95% CI)) were similar on day 1 (32 (22, 47)) l h(-1) and day 5 (38 (28, 51)) l h(-1) of daily artesunate administration but these mean values were approximately three fold higher compared with day -5 after a single dose (95 (56, 159)). In this group, artemisinin oral clearance increased from 196 (165, 232) l h(-1) on day 1-315 (241, 410) l h(-1) on day 5. In Group AM, dihydroartemisinin oral clearance on day 1 was 39 (34, 46) l h(-1) and increased 1.6 fold to 64 (48, 85) l h(-1) on day 5. In this group, artemisinin oral clearance increased sequentially (1.5 and 4.7 fold, respectively) from 207 (151, 285) l h(-1) on day -5-308 (257, 368) l h(-1) on day 1 and to 981 (678, 1420) l h(-1) on day 5. The increase in artemisinin oral clearance between days -5 and 1 (in the absence of artesunate) was similar to that between days 1 and 5 in Group AS subjects who took daily artesunate. Dihydroartemisinin was not a significant metabolite of artemisinin. CONCLUSIONS: Artesunate (dihydroartemisinin) did not alter the elimination of artemisinin. However, dihydroartemisinin elimination was inhibited by artemisinin. Artemisinin induced its own elimination even 5 days after a single oral dose. There was no evidence for the formation of dihydroartemisinin from artemisinin.

Administration, Oral↗
PubMed2001

Oral bioavailability of dihydroartemisinin in Vietnamese volunteers and in patients with falciparum malaria.

AIMS: To obtain comprehensive bioavailability data for artesunate (ARTS) and its active metabolite dihydroartemisinin (DHA) following their separate oral administration to Vietnamese volunteers and to patients with acute, uncomplicated falciparum malaria. METHODS: Volunteers were randomized to receive either i.v. ARTS (120 mg) followed by oral ARTS (150 mg) 8 h later (Group 1, n = 10), or i.v. ARTS (120 mg) followed by oral DHA (120 mg) 8 h later. Patients, also received oral ARTS (150 mg; Group 3, n = 8) or DHA (120 mg; Group 2, n = 7), in a randomized cross-over study design. Multiple blood samples were collected after each administration and plasma ARTS and/or DHA concentrations were determined by h.p.l.c. Pharmacokinetic descriptors were obtained from noncompartmental analysis and bioavailability was calculated from AUC data. In the patients, the time to 50% parasite clearance (PCT50) and fever clearance time (FCT) also were measured. RESULTS: In Group 1 (volunteers), the mean (95% CI) absolute bioavailability of oral ARTS was 80% (62,98%), while in Group 2 (volunteers), the bioavailability of oral DHA was 45% (34,56%). In the patients (Group 3), the bioavailability of oral DHA relative to oral ARTS was 88% (49,127%). The median PCT50 and FCT were 2.3 and 28 h, respectively. CONCLUSIONS: The study shows that the absolute bioavailability of DHA was significantly lower than that for ARTS in healthy volunteers. The bioavailability of ARTS in volunteers was consistent with previous studies in patients with uncomplicated falciparum malaria. The dose-normalized Cmax and AUC(0,infinity) for DHA were significantly greater in patients with falciparum malaria than in healthy volunteers. The high relative bioavailability of DHA in the patients may have been due to lower first-pass clearance. We conclude that, for the treatment of malaria, DHA is likely to be a suitable oral substitute for ARTS. Based on our mean AUC measurements, it appears that equal doses of DHA and ARTS (mg basis) should give equivalent systemic exposure to bioactive DHA in uncomplicated falciparum malaria.

Administration, Oral↗
PubMed2001

Antiplasmodial and antioxidant isofuranonaphthoquinones from the roots of Bulbine capitata.

The roots of B. capitata yielded the new compounds 5,8-dihydroxy-1-tigloylmethylnaphtho[2,3-c]furan-4,9-dione, 1-acetoxymethyl-8-hydroxynaphtho[2,3-c]furan-4,9-dione, and 1-acetoxymethyl-5,8-dihydroxynaphtho[2,3-c]furan-4,9-dione, in addition to the known compounds chrysophanol, 10,10'-chrysophanol bianthrone, 8-hydroxy-1-methylnaphtho[2,3-c]furan-4,9-dione, 5,8-dihydroxy-1-methylnaphtho[2,3-c]furan-4,9-dione, 5,8-dihydroxy-1-hydroxymethylnaphtho[2,3-c]furan-4,9-dione, and 8-hydroxy-5-methoxy-1-methylnaphtho[2,3-c]furan-4,9-dione, or 5-hydroxy-8-methoxy-1-methylnaphtho[2,3-c]furan-4,9-dione. The new as well as the known isofuranonaphthoquinones showed antioxidant and weak antiplasmodial activities.

Animals↗
PubMed2001

Treatment of falciparum malaria in Vietnamese children: the need for combination therapy and optimized dosage regimens.

To assess the in vivo sensitivity of Plasmodium falciparum to mefloquine and artesunate in a hyperendemic area of southern Viet Nam, we studied 41 children and 21 adults from a remote commune who had uncomplicated falciparum malaria without previous treatment. Patients were randomly allocated to artesunate (4 mg/kg on day 0 and 2 mg/kg on days 1-4) or mefloquine (10 mg/kg followed by 5 mg/kg at 6 h). Serial assessments were performed over 28 days. Of 31 patients allocated artesunate, nine (29%) redeveloped parasitaemia during follow-up compared with 23% (seven of 30) who received mefloquine. Of the 41 children, 15 (37%) had recrudescence/re-infection compared with only one of 20 adults (5%; p < 0.001). Significantly more children than adults failed on mefloquine treatment (37% vs 0%; p = 0.021) and one case showed RIII resistance. There was no significant difference in the case of artesunate. In regression analysis, parasitaemia was an independent predictor of recrudescence/re-infection after mefloquine (p = 0.02). These data support the use of combination therapy such as artesunate plus mefloquine for falciparum malaria in a hyperendemic area of Viet Nam. Primarily because of their greater parasite densities, children should be given higher doses of mefloquine (e.g. 25 mg/kg).

Adolescent↗
PubMed2001

Serum C-reactive protein concentrations in Malaysian children with enteric fever.

To investigate the role of serum C-reactive protein (CRP) in the diagnosis of typhoid fever, we studied 227 febrile Malaysian children hospitalized during a 12-month period. The children were: culture-positive for Salmonella typhi (Group 1; n = 108); culture-negative but with typical clinical features of typhoid fever (Group 2; n = 60); or had non-typhoidal illness (Group 3; n = 59). Group 1 children had the highest serum CRP concentrations (geometric mean [SD range]; 43 [12-150] mg/l vs. 26 [8-85] mg/l in Group 2 and 21 [4-110] mg/l in Group 3; p < 0.001). In regression analysis, age, patient group and fever duration were independently associated with serum CRP (p < 0.05) but gender was not. In Group 1 patients, there was a significant positive association between serum CRP and Widal O and H agglutinin titres. In receiver-operator characteristic (ROC) analysis of serum CRP for Groups 1 and 2 combined, compared with Group 3, the area under the curve (AUC) was 0.65. These data show that the serum CRP is highest in culture-positive children with enteric fever and reflects the immune response to the infection in this group. Nevertheless, serum CRP had relatively low sensitivity and specificity for confirmed or clinically diagnosed typhoid fever (68 and 58 per cent, respectively at 'cut-off' concentration 30.0 mg/l), and an AUC value only moderately above that associated with no predictive power (0.5). Although of limited use as a primary diagnostic test, a raised serum CRP may still have a place as one of a range of features that facilitate assessment of a febrile child in a typhoid-endemic area.

C-Reactive Protein↗
PubMed2001

Pharmacokinetics and pharmacodynamics of intravenous artesunate in severe falciparum malaria.

To provide novel data relating to the dispositions, effects, and toxicities of the artemisinin derivatives in severe malaria, we studied 30 Vietnamese adults with slide-positive falciparum malaria treated with intravenous artesunate. Twelve patients with complications (severe; group 1) and 8 patients without complications but requiring parenteral therapy (moderately severe; group 2) received 120 mg of artesunate by injection, and 10 patients with moderately severe complications (group 3) were given 240 mg by infusion. Serial concentrations of artesunate and its active metabolite dihydroartemisinin in plasma were measured by high-performance liquid chromatography. The time to 50% parasite clearance (PCT(50)) was determined from serial parasite densities. Full clinical (including neurological) assessments were performed at least daily. In noncompartmental pharmacokinetic analyses, group mean artesunate half-lives (t(1/2)) were short (range, 2.3 to 4.3 min). The dihydroartemisinin t(1/2) (range, 40 to 64 min), clearance (range, 0.73 to 1.01 liters/h/kg), and volume of distribution (range, 0.77 to 1.01 liters/kg) were also similar both across the three patient groups (P > 0.1) and to previously reported values for patients with uncomplicated malaria. Parasite clearance was prompt (group median PCT(50) range 6 to 9 h) and clinical recovery was complete under all three regimens. These data indicate that the pharmacokinetics of artesunate and dihydroartemisinin are not influenced by the severity of malaria. Since the pharmacokinetic parameters for both artesunate and dihydroartemisinin were similar regardless of whether injection or infusion was used, artesunate can be considered a prodrug that is converted stoichiometrically to dhydroartemisinin. Conventional doses of artesunate are safe and effective when given to patients with complications of falciparum malaria.

Adult↗
PubMed2001

Trauma, symptoms of posttraumatic stress disorder, and associated problems among incarcerated veterans.

OBJECTIVE: To help improve treatment for incarcerated veterans, the study examined exposure to trauma, symptoms of posttraumatic stress disorder (PTSD), functional status, and treatment history in a group of incarcerated veterans. METHODS: A convenience sample of 129 jailed veterans who agreed to receive outreach contact completed the Life Event History Questionnaire, the PTSD Checklist-Civilian Version (PCL-C), and the Addiction Severity Index. Participants who had scores of 50 or above on the PCL-C, designated as screening positive for PTSD, were compared with those whose scores were below 50, designated as screening negative for PTSD. RESULTS: Some 112 veterans (87 percent) reported traumatic experiences. A total of 51 veterans (39 percent) screened positive for PTSD, and 78 veterans (60 percent) screened negative. Compared with veterans who screened negative for PTSD, those who screened positive reported a greater variety of traumas; more serious current legal problems; a higher lifetime use of alcohol, cocaine, and heroin; higher recent expenditures on drugs; more psychiatric symptoms; and worse general health despite more previous psychiatric and medical treatment as well as treatment for substance abuse. CONCLUSIONS: The findings encourage the development of an improved treatment model to keep jailed veterans with PTSD from repeated incarceration.

Adult↗
PubMed2001

Relationship between ethnicity and glycemic control, lipid profiles, and blood pressure during the first 9 years of type 2 diabetes: U.K. Prospective Diabetes Study (UKPDS 55).

OBJECTIVE: To assess the relationship among self-reported ethnicity, metabolic control, and blood pressure during treatment of type 2 diabetes. RESEARCH DESIGN AND METHODS: We studied 2,999 newly diagnosed type 2 diabetic patients recruited to the U.K. Prospective Diabetes Study who were randomized to conventional or intensive glucose control policies if their fasting plasma glucose levels remained >6 mmol/l after a dietary run-in. A total of 2,484 patients (83%) were white Caucasian (WC), 265 patients (9%) were Afro-Caribbean (AC), and 250 patients (8%) were Asian of Indian origin (IA). Variables were assessed at 3, 6, and 9 years. RESULTS: During the 9-year study period, body weight increased more in WC patients (mean 5.0 kg) than in AC (3.0 kg) and IA (2.5 kg) patients (P < 0.001). After adjusting for age, sex, baseline value, treatment allocation, and change in weight, there were no consistent ethnic differences in mean change in fasting plasma glucose or HbA(1c). After adjustment for antihypertensive therapy, increase in systolic blood pressure at 9 years was greatest in AC patients (7 mmHg; P < 0.01 vs. WC patients). Mean diastolic blood pressure, total cholesterol, and LDL cholesterol decreased progressively during the 9 years in each group. In AC patients, the mean increase in HDL cholesterol (0.16 mmol/l) at 3 years, maintained to 9 years, and the mean decrease in plasma triglyceride level (0.4 mmol/l) at 9 years were greater than in WC and IA patients (P < 0.001). CONCLUSIONS: This study shows important ethnic differences in body weight, lipid profiles, and blood pressure, but not glycemic control, during 9 years after diagnosis of type 2 diabetes. AC patients maintained the most favorable lipid profiles, but hypertension developed in more AC patients than WC or IA patients. Ethnicity-specific glycemic control of type 2 diabetes seems unnecessary, but other risk factors need to be addressed independently.

Blood Glucose↗
PubMed2001

Pituitary-adrenal function in uncomplicated falciparum malaria.

To investigate pituitary-adrenal function in acute uncomplicated falciparum malaria, we performed an overnight dexamethasone suppression test in 13 Vietnamese adults with acute malaria and 6 healthy controls. After blood samples were taken for serum cortisol and plasma ACTH at 23.00 hours on the admission day, 1 mg dexamethasone was given and further samples were taken at 08.00, 16.00 and 23.00 hours the next day. The patients received conventional antimalarial and supportive treatment. Baseline plasma ACTH concentrations in the patients [3.9 (0.2-41.2) pmol/l] and controls [3.4 (1.1-4.3) pmol/l] were similar (p=0.51), and exhibited a similar fall after dexamethasone to 0.6 (0.2-2.5) and 0.9 (0.7-1.6) pmol/l at 08.00 hours respectively (p<0.03 vs 23.00 hour values). Serum cortisol levels before dexamethasone were higher in the patients than in the controls [456 (102-821) vs 145 (64-183) nmol/l respectively; p=0.007] and the overnight fall was less in the patients [208 (26-340) and 23 (15-46) nmol/l at 08.00 hours respectively; p<0.001 vs 23.00 hour values and between groups]. Between 08.00 and 23.00 hours, plasma ACTH and serum cortisol remained suppressed in the controls. In the patients, the serum cortisol continued to fall progressively towards control values. These data suggest that there is a raised set point for cortisol inhibition of ACTH secretion but normal corticotrophin responsiveness to dexamethasone in uncomplicated malaria. A raised serum cortisol after dexamethasone in the patients might reflect the combination of a prolonged cortisol half-life and the stimulatory effects of cytokines on the adrenal cortex, with a consequent protective effect against complications such as hypoglycemia.

Adrenal Glands↗