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Biomedical subjects

P Chanthavanich

Publications and source records attributed to P Chanthavanich.

At least 37 records · Page 2Linked to original sources
PubMed1989

Failure of interferon alfa and tribavirin in rabies encephalitis.

OBJECTIVE: To test the effect of interferon alfa and tribavirin (ribavirin) in patients with rabies encephalitis. DESIGN: An open trial of chemotherapy and intensive care in patients with early rabies. SETTING: The intensive care unit of a Bangkok hospital. PATIENTS: Four conscious men with clinical rabies encephalitis. INTERVENTIONS: Rapid virological diagnosis of rabies. Treatment with intravenous and intraventricular injections of high doses of lymphoblastoid interferon alfa in three patients and tribavirin in one patient. Intensive care was given throughout. MAIN OUTCOME MEASURES: Rabies infection confirmed by antigen detection and virus isolation. Rabies neutralising antibody and specific IgM sought in serum and cerebrospinal fluid. Interferon concentrations monitored before and during treatment in three patients. RESULTS: Interferon alfa treatment produced high concentrations in serum and cerebrospinal fluid. All four patients died after 5 1/2 to 12 1/2 days of treatment with no evidence of virostatic or clinically beneficial effects from either treatment. CONCLUSION: Interferon alfa treatment is not effective in rabies encephalitis. The use of tribavirin warrants further study, possibly combined with new therapeutic methods.

Adolescent↗
PubMed1989

Repeated doses of albendazole against strongyloidiasis in Thai children.

Fifty children aged 5 to 12 years whose fecal examination confirmed of strongyloidiasis were divided into 2 groups. One group (Group I) of 26 received 400 mg albendazole once a day for 3 consecutive days. The other group (Group II) of 24 received the same dosage but repeated a week later. Simple smear fecal examination was performed for 3 consecutive days before treatment, and stool cultures were performed on Days 13, 14, 15 21, 22 and 23 after treatment. Evaluation of successful treatment or cure was based on the absence of larvae in 6 culture specimens. The cure rates were 80.8% in Group I and 91.7% in Group II (p = 0.18). Side effect consisted of mild and transient vomiting in one patient in each group. Although the difference in cure rates between the two drug regimens was not statistically different, two courses of treatment (Group II) resulted in a higher cure rate.

Albendazole↗
PubMed1988

Cerebral anaerobic glycolysis and reduced cerebral oxygen transport in human cerebral malaria.

In 12 patients comatose with cerebral malaria, cerebral blood flow was 52.2 (SE 4.0) ml/100 g per min, within the reported range for healthy controls, but cerebral vascular resistance was raised at 1.66 (0.19) mm Hg/ml per 100 g per min. Cerebral oxygen consumption (1.90 [0.23] ml/100 g per min), and cerebral arteriovenous oxygen content difference (3.5 [0.43] ml/dl) were subnormal, while cerebral venous pO2 (5.7 [0.2] kpA) was raised. After recovery of consciousness there were significant decreases in arterial lactate concentration (2.44 [0.45] to 1.19 [0.45] mumol/l) and cerebral lactate production (17.4 [7.9] to 5.6 [1.1] mmol/100 g per minute). These results provide evidence of cerebral anaerobic glycolysis associated with inadequate oxygen delivery to the brain consistent with either inhibition of cerebral oxidative metabolism or the microcirculatory obstruction envisaged in the "mechanical" hypothesis for cerebral malaria.

Adolescent↗
PubMed1988

Single dose phenobarbitone prevents convulsions in cerebral malaria.

48 patients over 6 years of age with strictly defined cerebral malaria were randomised to receive either a single intramuscular injection of phenobarbitone (3.5 mg/kg) or placebo in a double-blind, placebo-controlled study. Phenobarbitone significantly reduced the incidence of subsequent convulsions from 54% to 12.5%, without adverse effects. A single intramuscular injection of phenobarbitone is a simple, cheap, and effective method for prevention of convulsions in cerebral malaria.

Adolescent↗
PubMed1988

Mepacrine accumulation during treatment of chloroquine-resistant falciparum malaria.

Oral mepacrine dihydrochloride, 200 mg (158 mg of the base) six-hourly for five doses followed by 100 mg (79 mg of the base) eight-hourly for six days (half dosage for those less than or equal to 50 kg) was given to 21 patients with high-grade chloroquine-resistant falciparum malaria in eastern Thailand. Fifteen patients (71%) had a clinical response [fever clearance time of 81 +/- 35 hours (mean +/- S.D.)] and 13 (62%) had complete clearance of parasitaemia (clearance time 92 +/- 42 hours). Two patients were cured, but 11 patients returned with recurrent parasitaemia between 11 and 40 days after starting treatment. Five patients had an R2 response and three had an R3 response. Mepacrine retains some activity against chloroquine-resistant falciparum malaria but it cannot be recommended for use in Thailand. The doses used, which are those also recommended for giardiasis, led to progressive and potentially toxic mepacrine accumulation. Further evaluation of regimens which produce safer plasma concentration profiles is needed.

Adolescent↗
PubMed1988

In vivo and in vitro responses to quinine and quinidine of Plasmodium falciparum.

A total of 66 Thai children with uncomplicated falciparum malaria were treated orally with regimens of either quinine or quinidine. Radical cures were observed in 85% (28 of 33) of the children who received quinine and in 88% (29 out of 33) of those who received quinidine. Treatment failures in both groups were RI responses.The mean trough level of quinidine (10 mumol/l) was about 2.5-times less than that of quinine (25 mumol/l). The electrocardiograms of the two treatment groups differed significantly in that there was an acute prolongation of the QT(c) interval in 56% of those who received quinidine compared with 21.0% of those given quinine. In vitro assays of the pretreatment drug susceptibilities of the isolates of Plasmodium falciparum indicated that the mean minimum inhibitory concentration (MIC) for quinidine (1.44 mumol/l) was about half that for quinine (3.02 mumol/l). Although both drugs are equally effective, quinine is recommended for treatment of multidrug-resistant malaria in paediatric patients, primarily because of the cardiac effects produced by quinidine.

Animals↗
PubMed1987

Antibody response to suckling mouse brain rabies vaccines for post exposure treatment.

A new suckling mouse brain vaccine (SMBV) against rabies, produced by the Thai Red Cross Society, was compared with the well established Institut Pasteur SMBV in patients with very low risk rabies contact. The 4 regimens used were the standard daily injections with booster doses of Thai Red Cross vaccine (TRCV) and Institut Pasteur Vaccine (IPV), and a reduced dose scheme of 6 injections as used for tissue culture vaccines. The effect of 20 IU/kg of human rabies immune globulin (HRIG) was tested on each regimen, making 8 groups, a total of 122 patients. Blood samples taken on days 0, 7, 14, 28 and 91 were tested for neutralizing antibody. Only the standard IPV regimen produced antibody in every patient; all had levels greater than 0.5 IU at some stage. Two people (13%) given the standard TRCV produced no detectable antibody (less than or equal to 0.1 IU) throughout the study. The reduced dose regimens gave very low antibody levels. 7% of the IPV and 76% of the TRCV groups failed to produce antibody on any occasion. The antibody response was significantly suppressed by the administration of HRIG. Compared to the original South American SMBV, the vaccines tested induced low levels of short lived antibody. No reduction in the dosage of SMBV should be considered unless the potency of the product is adequate.

Adult↗
PubMed1987

Purified chick embryo cell rabies vaccine: economical multisite intradermal regimen for post-exposure prophylaxis.

The standard six-dose intramuscular (i.m.) rabies post-exposure vaccine regimen using a new purified chick embryo cell (PCEC) vaccine was compared with two economical multisite intradermal (i.d.) PCEC regimens, a multisite i.m. PCEC schedule and a subcutaneous regimen using a suckling mouse brain (SMB) rabies vaccine manufactured in Thailand. The neutralizing antibody results for the four-site and eight-site i.d. and the standard i.m. PCEC regimens were similar over 3 months. A three-site i.m. PCEC regimen had no advantage. The SMB vaccine gave the lowest antibody levels. Human rabies immune globulin therapy significantly increased the GMT of all groups on day 7, unlike equine antirabies serum (EARS). Both antisera suppressed antibody responses to PCEC on days 14 and 28. Three generalized reactions probably related to EARS were the only serious side effects. An eight-site i.d. PCEC vaccine regimen proved as immunogenic as the routine i.m. schedule and, if implemented as post-exposure prophylaxis, would be the cheapest widely available tissue culture vaccine regimen. The protective efficiency should now be tested in patients bitten by rabid animals.

Adolescent↗
PubMed1987

Early antibody responses to rabies post-exposure vaccine regimens.

The aim of post-exposure rabies vaccine treatment is to induce immunity, measured as neutralizing antibody, as fast as possible. This is especially important in the tropical rabies-endemic areas where simultaneous passive prophylaxis with hyperimmune serum is not practicable in the majority of cases. We compared the rate of production of antibody during the first two weeks, by six vaccine regimens in 118 subjects using two tissue culture vaccines, human diploid cell strain vaccine (HDCSV) and purified Vero cell rabies vaccine (PVRV). No antibody was detected on day 5. On day 7, the highest seroconversion rate was seen in subjects given HDCSV intramuscularly at two sites on days 0 and 3 (7 of 15), but this was not significantly different from the group with the lowest rate: the conventional single-site intramuscular regimen. All subjects had antibody by day 14, at which time the highest geometric mean titer was in the group vaccinated with 0.25 ml doses of diploid cell vaccine given subcutaneously at eight sites. This regimen, together with the standard single-site diploid cell vaccine and an eight-site intradermal regimen of the same product gave significantly higher titers than the two-site intramuscular regimens of either product. No single immunization schedule emerges as best, so the speed of antibody response, economy, and the skill needed for intradermal injection should be considered when deciding on the optimum regimen for use in a particular geographic area.

Antibodies, Viral↗
PubMed1986

New purified Vero-cell vaccine prevents rabies in patients bitten by rabid animals.

The protective effect of a new, potentially economical tissue-culture rabies vaccine, purified vero-cell rabies vaccine (PVRV), was tested in 106 patients bitten by animals with proven rabies. 0.5 ml PVRV was given intramuscularly on days 0, 3, 7, 14, 28, and 91; 47 patients with severe exposure were also given 20 IU/kg human rabies immune globulin (HRIG). All patients are alive and well after 1 year. Side-effects of treatment were negligible. Rabies neutralising antibody (greater than or equal to 1.6 IU) was demonstrated on day 14 and persisted for 1 year in every case. There was no significant suppression of the antibody response by HRIG. If the untreated mortality is 15%, PVRV is 81% efficient in protecting patients against rabies encephalitis (95% confidence limit). PVRV is likely to replace human diploid-cell strain vaccine as the most widely used tissue-culture rabies vaccine.

Adolescent↗
PubMed1986

Hypoglycaemia and antimalarial drugs: quinidine and release of insulin.

Life threatening hypoglycaemia has been closely associated with the use of quinine, but the effect of quinidine and the synthetic antimalarials on the homoeostasis of glucose has not been investigated. In volunteers given a fixed dose of 500 mg base and patients with malaria given a quinidine loading dose (15 mg base/kg) mean (SEM) plasma insulin concentrations rose from 6.1 (1.5) mU/l to 10.9 (4.4) mU/l (p less than 0.02) and 10.4 (2.0) mU/l to 18.5 (5.3) mU/l (p less than 0.04), respectively. Plasma glucose concentrations fell from 4.5 (1.1) mmol/l (81 (20) mg/100 ml) to 4.0 (0.3) mmol/l (72 (5) mg/100 ml) in volunteers (p less than 0.04) and from 5.7 (1.3) mmol/l (102 (23) mg/100 ml) to 4.8 (1.6) mmol/l (86 (29) mg/100 ml) in patients (p less than 0.05). One of two patients with cerebral malaria and acute renal failure became profoundly hypoglycaemic (plasma glucose concentration 1.4 mmol/l (25 mg/100 ml), plasma insulin concentration 3.1 mU/l). Hypoglycaemia may occur in any severely ill fasting patient given parenteral quinidine. The other antimalarials tested, chloroquine, amodiaquine, mefloquine, and halofantrine, did not stimulate the release of insulin, an important advantage that should be taken into account when treatment is chosen for Plasmodium falciparum malaria.

Amodiaquine↗
PubMed1986

Prediction, prevention, and mechanism of early (anaphylactic) antivenom reactions in victims of snake bites.

Victims of snake bites are often subjected to cutaneous or conjunctival hypersensitivity testing before being given antivenom. None of 12 early (anaphylactic) reactions was predicted by these tests in 25 Nigerian and Thai patients. The incidence and severity of early reactions was the same whether antivenom was given by intravenous injection over 10 minutes or diluted and given as an intravenous infusion over 30 minutes. Although antivenom activated complement in vitro, there was no evidence of complement activation or formation of immune complexes in patients bitten by snakes who were treated with antivenom, whether or not they developed early reactions. Higher doses of antivenom might induce the complement activation and formation of immune complexes (aggregates) that have been observed during the clinically more severe reactions associated with homologous immunoglobulin treatment.

Anaphylaxis↗
PubMed1986

Purified Vero cell rabies vaccine and human diploid cell strain vaccine: comparison of neutralizing antibody responses to post-exposure regimens.

Neutralizing antibody responses to conventional rabies post-exposure regimens of human diploid cell strain vaccine (HDCSV) and the new purified Vero cell rabies vaccine (PVRV) were compared in 58 healthy Thai veterinary students. The geometric mean titres (GMTs) of the group given HDCSV were slightly higher than those given PVRV, but on day 28 the peak GMTs of the two groups were statistically similar. The early antibody response to PVRV was unaffected by the addition of passive immunization, whereas the level of HDCSV response was reduced on day 14, so that there was no difference on that day between the GMTs of the two vaccine groups given HRIG. However, by day 91 the GMT of those given PVRV and HRIG was lower than in those given HDCSV alone or with HRIG. The appearance of antibody was less rapid than was observed in previous studies using multiple-site intradermal vaccination. Side effects were trivial. Our results confirm the promise of this new, potentially more economical tissue culture vaccine, but they suggest that the regimen could be improved.

Adolescent↗
PubMed1986

Antigen-specific immunosuppression in human malaria due to Plasmodium falciparum.

Proliferative responses of T lymphocytes to antigens specific and not specific for malaria were investigated in 32 adult patients in eastern Thailand during acute infection with Plasmodium falciparum malaria and during their convalescence. Immune unresponsiveness to malarial antigen, which persisted for more than four weeks in 37.5% of the individuals, was present in all patients, irrespective of parasitemia or severity of clinical illness. Suppression of responses to nonspecific antigens was less profound and observed only in patients with moderately severe or cerebral malaria. The depressed functional responses were associated with a loss of T lymphocytes--both helper and suppressor subsets--from the peripheral blood; these responses were recovered once parasites were cleared. These results indicate that blood-stage plasmodial infections may suppress responses important for immunity to malaria and so allow the parasite to survive. They further suggest that patients acutely or even recently infected with P. falciparum may not respond as well to a malaria vaccine as would uninfected individuals.

Adolescent↗
PubMed1986

Cardiovascular toxicity and distribution kinetics of intravenous chloroquine.

Chloroquine diphosphate (3 mg base kg-1) was given by constant rate intravenous injection over 10 min to 12 healthy adult male volunteers. Plasma concentrations of chloroquine and the principal metabolite desethylchloroquine, electrocardiograph intervals, and arterial blood pressure were measured at frequent intervals to determine the relationship between cardiovascular effects and plasma concentrations. Peak plasma concentrations ranged between 784 and 6649 (mean 2913) ng ml-1. The decline in plasma concentrations was multiexponential with an initial rapid distribution phase; mean (+/- s.d.) first order rate constant 0.65 +/- 0.14 min-1, and an estimated apparent volume of the central compartment of 0.18 +/- 0.15 l kg-1. There was no serious toxicity, but subjective side effects were reported in all patients and there was a significant fall in systolic blood pressure (110 +/- 9.5 to 101 +/- 12.5 mm Hg; P = 0.03) and rise in heart rate which paralleled the change in plasma chloroquine concentrations. Coincident with changes in blood pressure, there was a significant prolongation of the electrocardiograph QRS interval; 81 +/- 15 to 92 +/- 13 ms (P less than 0.01) but no change in the QTc interval. These findings suggest that the cardiovascular toxicity of parenteral chloroquine is related to transiently high plasma concentrations occurring early in the distribution phase. This results from incomplete distribution from a central compartment that is approximately one thousand times smaller than the eventual total apparent volume of distribution at steady state. Rate of administration is therefore a major determinant of toxicity.

Adolescent↗
PubMed1986

Evidence against immune haemolysis in falciparum malaria in Thailand.

Evidence of immune mediated haemolysis was sought in 83 patients with P. falciparum malaria in eastern Thailand. Amongst 73 patients with uncomplicated infection 12 (16.4%) had a weakly positive direct antiglobulin test (DAT). The incidence in 32 children aged 8-16 years was similar to that in adults. Of 10 patients with cerebral malaria, six adults, all of whom were in unrousable coma, had a positive DAT. Erythrocyte-bound IgG1 accounted for the positive DAT in all cases; sensitization with complement or other IgG subclasses was not found. Patients with uncomplicated malaria had a median value of 70 IgG molecules per erythrocyte compared with 65 molecules per cell in 67 healthy controls. This difference was not statistically significant but could account for the lower incidence of a positive DAT in control subjects (4.5%). There was no correlation between the number of IgG molecules per cell and the degree of anaemia during the acute or convalescent phases of the infection. There is no evidence from this study that an immunohaemolytic process contributes to the anaemia of falciparum malaria in eastern Thailand.

Adolescent↗
PubMed1986

Randomized comparative trial of three monospecific antivenoms for bites by the Malayan pit viper (Calloselasma rhodostoma) in southern Thailand: clinical and laboratory correlations.

Three monospecific antivenoms for Malayan pit viper (MPV) (Calloselasma rhodostoma) were compared in Southern Thailand, where this species is the most common cause of snake bite morbidity. Forty-six patients with proved MPV bites and incoagulable blood, indicating systemic envenoming, were randomly allocated for treatment with Thai Red Cross (TRC), Thai Government Pharmaceutical Organization (GPO), or Twyford Pharmaceutical monospecific antivenoms. Both GPO and Twyford antivenoms produced rapid and permanent restoration of blood coagulability, but TRC antivenom failed in 2/15 cases. Patients in the GPO group showed the greatest increase in plasma fibrinogen concentration during the first 24 hr and had fewer early anaphylactic reactions (6/15) compared with Twyford 8/16 and with TRC 13/15. Pyrogenic reactions occurred more frequently after TRC antivenom (8/15) than GPO (1/15) or Twyford (0/16). Patients requiring more than one dose of antivenom were identifiably more severely envenomed on admission. In an accompanying laboratory study the antivenoms were assessed in rodents using five WHO standard tests of neutralizing activity. Compared with the other two antivenoms TRC was significantly inferior in anti-lethal potency, GPO was superior in anti-hemorrhagic and anti-necrotic potency and Twyford was superior in anti-procoagulant and anti-defibrinogenating potency. The clinical efficacy of these antivenoms against local necrosis remains equivocal. GPO and Twyford antivenoms are recommended for the treatment of systemic envenoming by MPV in an initial dose of 5 ampoules.

Adult↗