Interactive alterations of arsenic and malathion in the disposition kinetics of pefloxacin

Assessment of deleterious effects produced by concurrent exposure to commonly encountered chemicals is of great concern to find out toxicological consequences arising as a result of their interactions and for a more comprehensive management of chemical-induced untoward effects. The naturally occurring heavy metal arsenic is present in food and water. Malathion is one of the most widely used pesticides in agriculture and public health practices worldwide. Humans, animals, and birds are exposed to these chemicals through environmental processes. Since arsenic and malathion are shown to exert an inhibitory effect on cytochrome P450 activities, their continuous exposure may alter the disposition kinetics of drugs that are predominantly metabolized hepatically. The current study was undertaken to evaluate the impact of subchronic exposure of arsenic, malathion, and their combination on the disposition kinetics of widely used fluoroquinolone antimicrobial pefloxacin in chickens. Broiler chickens were exposed to either arsenic (50 ppm), malathion (500 ppm), or arsenic (50 ppm) plus malathion (500 ppm). Arsenic and malathion were given in drinking water and feed, respectively. Following 28 days of exposure, all birds received a single oral dose of pefloxacin (10 mg/kg) and the plasma concentrations and the disposition kinetic parameters of the drug were determined. In the birds not exposed to arsenic and/or malathion, the elimination half-life (t(1/2beta)), area under the plasma concentration-time curve (AUC), maximum plasma drug concentration (C(max)), mean residence time (MRT), and bioavailability of pefloxacin were 8.46 +/- 0.24 h, 39.06 +/- 1.13 microg.h.ml(-1), 2.69 +/- 0.19 microg.ml(-1), 12.29 +/- 0.48 h, and 60.52 +/- 1.74%, respectively. Exposure to arsenic was associated with a significant increase in C(max) (4.28 +/- 0.45 microg.ml(-1)) and a nonsignificant increase in the values of AUC (48.96 +/- 2.55 microg.h.ml(-1)) and bioavailability (74.55 +/- 3.8 %) of pefloxacin. The values of AUC (51.62 +/- 4.76 microg.h.ml(-1)), t(1/2beta) (12.57 +/- 1.26 h), MRT (19.94 +/- 1.99 h), and bioavailability (78.59 +/- 7.25 %) of pefloxacin were significantly increased in malathion-exposed birds. Concomitant exposure to arsenic and malathion did not affect the disposition kinetic variables of pefloxacin. The study shows that subchronic malathion exposure significantly alters the elimination kinetics of pefloxacin. Following concurrent exposure, arsenic nullifies the malathion-induced changes in disposition kinetics of pefloxacin by possibly diminishing the cytochrome P450-catalyzed bioactivation of malathion.

Residues of fluoroquinolone drugs in the cloacal gland and other tissues of Japanese quail

1. In this study we investigated the residues of fluoroquinolone drugs (ciprofloxacin and pefloxacin) in the cloacal gland (a site of foam synthesis) and other tissues such as breast muscle, testes, brain, kidney and plasma. 2. Fifty-four healthy male Japanese quail were selected at random from a flock, maintained under uniform husbandry conditions and divided into three groups, each of 18 birds. Group I (control) received 1 ml vehicle (normal saline 0.9% (w/v) NaCl) daily for 12 d through the intraperitoneal route. Birds of groups II and III received ciprofloxacin and pefloxacin by the same route at the rate of 10 and 12 mg/kg body weight, respectively, every day for a similar period. 3. Birds from each group were killed, at 1, 5 and 10 d after the cessation of treatment, to collect the cloacal gland together with other tissues that were analysed for residual drugs. 4. Cloacal gland retained the maximum drug residues of ciprofloxacin (60%) and pefloxacin (80%) on d 10 compared with that on d 1 after drug withdrawal. The drug residues were found 60 and 80% in ciprofloxacin and pefloxacin groups, respectively, in the cloacal gland tissue even on d 10 after withdrawal of the treatment. 5. In the ciprofloxacin-treated group, all tissues except cloacal gland contained very small amounts of the drug residues on d 10 after treatment ended. In the pefloxacin group the cloacal gland, breast muscle and kidney retained a fairly high amount of drug even on d 10 after treatment ceased. No residues of pefloxacin were detectable in testes and brain throughout. 6. In conclusion, the cloacal gland in Japanese quail acted as the largest sink for the fluoroquinolone drugs. Ciprofloxacin was more widely distributed in different tissues and persisted for a shorter period than pefloxacin.

Unplanned admissions following ambulatory plastic surgery--a retrospective study

INTRODUCTION

Admission for overnight or longer hospital stay from a day-case unit is an unwelcome event. This audit was designed to identify the incidence of unplanned admissions and also to detect the potential factors for such overstays.

PATIENTS AND METHODS

Details of plastic surgical day-case patients were obtained from the hospital records for a period of 6 months (February 2002 to July 2002).

RESULTS

The total number of unplanned admissions was 28 (3.55%). High rates were recorded in patients above the age of 80 years, male patients and body mass index > 30 kg/m2. Duration of surgery (> 45 min) and waiting time in the day surgery unit (> 2.5 h) had significant correlation with the overstays. Grade of the surgeon was not an important determinant factor. Of procedures which resulted in an unexpected admission, the most frequent were otoplasty (8.4%; n = 71) and fasciectomy for Dupuytren's contracture (14.5%; n = 41). Unexpected admissions were also high following rhinoplasty and nipple reconstruction but the total number of operations performed were not significant (n = 12 in each group). Overall, the cause of the overstays were mostly surgical (71.4%) followed by anaesthetic (28.5%) and social (7.1%).

DISCUSSION

With an overall unplanned admission rate of 3.55%, our unit is close to the national standard of 2-3%, as advocated by The Royal College of Surgeons of England. Postoperative bleeding (60%) was the most important surgical reason for overstays followed by intravenous antibiotics, wound drainage, excessive duration of the procedure and additional, unplanned procedures. Among the anaesthetic factors, postoperative pain was the leading cause (62.5%) followed by nausea, vomiting and adverse anaesthetic reaction.

CONCLUSIONS

The reasons for unplanned admissions are multifactorial and merit appropriate patient selection and proper estimation of the disease process.

In Vitro and In Vivo Evaluation of Guar Gum-Based Matrix Tablets of Rofecoxib for Colonic Drug Delivery

The present study was carried out to develop and evaluate guar gum-based matrix tablets of rofecoxib for their intended use in the chemoprevention of colorectal cancer. Matrix tablets containing 40% (RXL-40), 50% (RXL-50), 60% (RXL-60) or 70% (RXL-70) of guar gum were prepared by wet granulation technique, and were subjected to in vitro drug release studies. Guar gum matrix tablets released only 5 to 12% of rofecoxib in the physiological environment of stomach and small intestine. The matrix tablets RXL-40 disintegrated completely within 10 h in a dissolution medium without rat caecal contents (control study), and hence not studied further. When the dissolution study was continued in simulated colonic fluids (rat caecal content medium), the matrix tablets RXL-50 were acted upon by colonic bacterial enzymes releasing the entire quantity of drug wherein there was no appreciable difference when compared to that released in control study. The matrix tablets RXL-60 released another 88% of rofecoxib whereas matrix tablets RXL-70 released only 57% of rofecoxib in simulated colonic fluids indicating the susceptibility of the guar gum formulations to the rat caecal contents. The guar gum matrix tablets RXL-70 were subjected to in vivo evaluation in human volunteers to find their ability of targeting rofecoxib to colon. The delayed Tmax, prolonged absorption time (ta), decreased Cmax and decreased ka indicated that rofecoxib was not released significantly in stomach and small intestine, but was delivered to colon resulting in a slow absorption of the drug and making it available for local action in human colon.

Spontaneous keloids in siblings

The authors report two rare cases of 'non-syndromic spontaneous keloids' occuring in siblings. This represents another unexplored area in the field of 'keloid challenge', warranting further research and development.

Cutaneous changes in chronic alcoholics

BACKGROUND

Alcohol consumption can have a variety of cutaneous manifestations. Awareness of the cutaneous changes of alcohol abuse can allow early detection and intervention in an attempt to limit the adverse medical consequences. Hence a study was planned to determine the cutaneous changes in chronic alcoholics.

AIMS

To determine the cutaneous changes in chronic alcoholics.

METHODS

All the patients attending alcohol de-addiction camps were examined for cutaneous changes. The results were analyzed using Gausian test and compared with other reports.

RESULTS

Out of 200 alcoholics examined for cutaneous changes, 182 (91%) had cutaneous, nail, hair or oral cavity changes. Nail changes were found in 51 (25.5%) alcoholics, koilonychia being the commonest (16%). Oral changes were present in 107 (53.5%) alcoholics and changes due to nutritional deficiency in 20 (10%). Diseases due to poor hygiene were seen in 55 (27.5%) alcoholics. Tinea versicolor (14%) and seborrheic dermatitis (11.5%) were the commonest cutaneous changes noted.

CONCLUSION

Even though alcohol abuse has a variety of cutaneous manifestations and perhaps aggravates many diseases, there are no specific cutaneous signs of alcoholism. Knowledge of the spectrum of cutaneous manifestations of alcohol abuse can allow its early detection and treatment in an attempt to minimize the medical consequences.

Pattern of skin diseases in an Indian village

Disease pattern in a given population is generally determined by different ecological factors. Thus the objective of our study was to find out the pattern of skin diseases in a given population. Analysis of 3673 patients attending a medical camp at Kumble in Kerala state showed 410(11.16%) patients with dermatological problems. 260(63.41%) of them were males and 150(36.59%) females with a male to female ratio of 1.7:1. Of these patients, 178(43.41%) had cutaneous infections and 234(57.07%) had non-infectious dermatoses. Few patients had more than one dermatoses. Fungal infection was the commonest infection seen (22.92%) and eczemas took an upper hand in non-infectious group (32.19%). Improvement in the standard of living, education of the general public, improvement in the environmental sanitation and good nutritious food may help us to bring down the skin disease in this area.

Pharmacokinetic disposition of subcutaneously administered enrofloxacin in goats

The pharmacokinetic disposition of enrofloxacin was studied in goats after subcutaneous (s.c.) administration at a single dose of 7.5 mg/kg body weight. Blood samples were drawn from a jugular vein into heparinized tubes at predetermined time intervals after administration of the drug and the plasma was separated by centrifugation. The concentrations of enrofloxacin in the plasma were determined by a microbiological assay using Escherichia coli as the test organism. The plasma concentration-time data were analysed by non-compartmental methods. Enrofloxacin was rapidly absorbed, an appreciable concentration of the drug (0.30 +/- 0.13 microg/ml) being present in the plasma by 5 min after s.c. administration. The maximum plasma concentration of enrofloxacin and the time to reach that maximum were 2.91 +/- 0.39 microg/ml and 2.9 +/- 0.51 h. respectively. A detectable concentration of enrofloxacin persisted in the plasma for 12 h. The elimination half-life and mean residence time of enrofloxacin were 2.84 +/- 0.57 and 5.74 +/- 0.28 h, respectively. It is suggested that enrofloxacin given subcutaneously may be useful in the treatment of susceptible bacterial infections in goats.

Leprosy lesion on the prepuce of the male genitalia: a case report

A case of borderline leprosy in type I reaction with cutaneous lesions on the prepuce is reported. The need to examine the genitalia in all male leprosy patients is stressed.

Spectrophotometric determination of serum nitrite and nitrate by copper-cadmium alloy

A macro and micro assay for the spectrophotometric determination of serum nitrite and nitrate was developed. Nitrite/nitrate in biological samples can be estimated in a single step by this method. The principle of the assay is the reduction of nitrate by copper-cadmium alloy, followed by color development with Griess reagent (sulfanilamide and N-naphthylethylenediamine) in acidic medium. This assay is sensitive to 1 microM nitrate and is suitable for different biological fluids, including sera with a high lipid concentration. The copper-cadmium alloy used in the present method is easy to prepare and can completely reduce nitrate to nitrite in an hour. The present method provides a simple, cost-effective assay for the estimation of stable oxidation products of nitric oxide in biological samples.

Pharmacokinetics of pefloxacin in goats after intravenous or oral administration

The plasma concentrations and pharmacokinetics of the fluoroquinolone antimicrobial agent pefloxacin, following the administration of a single intravenous (10 mg/kg) or oral (20 mg/kg) dose, were investigated in healthy female goats. The antimicrobial activity in plasma was measured at predetermined times after drug administration by an agar well diffusion microbiological assay, using Escherichia coli (ATCC 25922) as the test organism. Concentrations of the drug > or = 0.25 microg/ml were maintained in plasma for up to 6 and 10 h after intravenous (i.v.) or oral administration of pefloxacin, respectively. The concentration time data for pefloxacin in plasma after i.v. or oral administration conformed to two- and one-compartment open models, respectively. Plasma pefloxacin concentrations decreased rapidly during the initial phase after i.v. injection, with a distribution half-life (t(1/2alpha)) of 0.10 +/- 0.01 h. The terminal phase had a half-life (t(1/2beta)) of 1.12 +/- 0.21 h. The volume of distribution at steady state (Vdss), mean residence time (MRT) and total systemic clearance (ClB) of pefloxacin were 1.08 +/- 0.09 L/kg, 1.39 +/- 0.23 h and 821 +/- 88 (ml/h)/kg, respectively. Following oral administration of pefloxacin, the maximum concentration in the plasma (Cmax) was 2.22 +/- 0.48 microg/ml and the interval from administration until maximum concentration (tmax) was 2.3 +/- 0.7 h. The absorption half-life (t(1/2ka)) mean absorption time (MAT) and elimination half-life of pefloxacin were 0.82 +/- 0.40, 4.2 +/- 1.0 and 2.91 +/- 0.50 h, respectively. The oral bioavailability of pefloxacin was 42% +/- 5.8%. On the basis of the pharmacokinetic data, a dosage regimen of 20 mg/kg, i.v. at 8 h intervals or orally twice daily, is suggested for treating infections caused by drug-sensitive pathogens in goats.

Effect of tamarind ingestion on fluoride excretion in humans

OBJECTIVE

To evaluate the effect of tamarind (Tamarindus indicus) ingestion on excretion of fluoride in school children.

DESIGN

Randomized, diet-control study.

SUBJECT

Twenty healthy boys were included and 18 of them completed the study.

INTERVENTIONS

Each subject consumed 10 g tamarind daily with lunch for 18 days at the social welfare boys' hostel. The nutrient composition of the daily diet was constant throughout the experimental period.

RESULTS

Tamarind intake led to significant increase (P<0.001) in the excretion of fluoride in 24 h urine (4.8+/-0.22 mg/day) as compared to excretion on control diet (3.5+/-0.22 mg/day). However, excretion of magnesium and zinc decreased significantly (7.11+/-1.48 mg of Mg and 252.88+/-12.84 microg of Zn per day on tamarind diet as compared to 23.39+/-3.68 mg of Mg and 331.78+/-35.31 microg Zn per day on control diet). Excretion of calcium and phosphorous were not significantly different while creatinine excretion decreased with tamarind intake (225.66+/-81 mg creatinine/day with tamarind and 294.5+/-78.76 mg creatinine/day without tamarind).

CONCLUSION

Tamarind intake is likely to help in delaying progression of fluorosis by enhancing urinary excretion of fluoride.

Pharmacokinetics of enrofloxacin and its metabolite ciprofloxacin in goats given enrofloxacin alone and in combination with probenecid

The pharmacokinetics of enrofloxacin and its active metabolite ciprofloxacin were investigated in goats given enrofloxacin alone or in combination with probenecid. Enrofloxacin was administered i.m. at a dosage of 5 mg x kg(-1) alone or in conjunction with probenecid (40 mg x kg(-1), i.v.). Blood samples were drawn from the jugular vein at predetermined time intervals after drug injection. Plasma was separated and analysed simultaneously for enrofloxacin and ciprofloxacin by reverse-phase high performance liquid chromatography. The plasma concentration-time data for both enrofloxacin and ciprofloxacin were best described by a one-compartment open pharmacokinetic model. The elimination half-life (t(1/2beta)), area under the plasma concentration-time curve (AUC), volume of distribution (V(d(area))), mean residence time (MRT) and total systemic clearance (Cl(B)) were 1.39 h, 7.82 microg x h x mL, 1.52 L x kg(-1), 2.37 h and 802.9 mL x h(-1) x kg(-1), respectively. Enrofloxacin was metabolized to ciprofloxacin in goats and the ratio between the AUCs of ciprofloxacin and enrofloxacin was 0.34. The t(1/2beta), AUC and MRT of ciprofloxacin were 1.82 h, 2.55 microg x h x mL and 3.59 h, respectively. Following combined administration of probenecid and enrofloxacin in goats, the sum of concentrations of enrofloxacin and ciprofloxacin levels > or = 0.1 microg x mL(-1) persisted in plasma up to 12 h.Co-administration of probenecid did not affect the t(1/2beta), AUC, V(d (area)) and Cl(B) of enrofloxacin, whereas the values of t(1/2beta) (3.85 h), AUC (6.29 microg x h x mL), MRT (7.34 h) and metabolite ratio (0.86) of ciprofloxacin were significantly increased. The sum of both enrofloxacin and ciprofloxacin levels was > or = 0.1 microg x mL(-1) and was maintained in plasma up to 8 h in goats after i.m. administration of enrofloxacin alone. These data indicate that a 12 h dosing regime may be appropriate for use in goats.

Intraoperative blood glucose levels in neurosurgical patients : an evaluation of two fluid regimens

Based on the evidence that hyperglycaemia aggravates ischaemic cerebral injury, it has been suggested that blood glucose levels be kept within 200 mg/dL during intracranial neurosurgery. Hypoglycaemia, however, can be a serious problem if glucose-containing solutions are avoided during the first four hours, as suggested in some studies. In order to explore the possibility of administering glucose in moderation so that the blood glucose levels are within acceptable limits, but at the same time the risk of hyoglycaemia is eliminated, we compared two intraoperative fluid regimens. Of the 52 neurosurgical patients studied, 32 patients received alternately 500 ml of 5% dextrose in normal saline and Ringer's lactate (DNS/RL Group) and 18 patients received alternately 500 ml of Ringer's lactate and normal saline (RL/NS Group). Blood glucose concentrations were determined at the end of each unit of fluid, until the patient received 4 units of fluid. In the DNS/RL group, blood glucose values peaked with the administration of each unit of DNS and tended to return towards the baseline with the subsequent RL, but remained higher than the previous control value. In the RL/NS group, there was a progressive increase in blood glucose values throughout the study period, but the increase was not statistically significant. The blood glucose levels were significantly different between the two groups after each unit of fluid except at the end of the fourth unit. Two patients in the RL/NS group had hypoglycaemia. In conclusion, the DNS/RL regimen maintains blood glucose levels within acceptable limits while avoiding the risk of hyperglycaemia. Withholding glucose completely, lowers blood glucose levels, but carries a risk of hypoglycaemia in some patients.

Release of iron from ferritin by metabolites of benzene and superoxide radical generating agents

The release of iron from ferritin in the presence of benzene metabolites, viz. phenol (P), catechol (CT), hydroquinone (HQ) and superoxide radical generating compounds, viz. pyrogallol (PL), phloroglucinol (PG), phenylhydrazine (PH) or phenylenediamine (PD) was studied in acetate buffer, pH 5.6. Monitoring the formation of the iron-ferrozine complex quantitated the release of iron from ferritin. The presence of P (125 microM) did not result in the release of iron from ferritin, whereas the same concentration of CT, HQ, PL, PH or PD resulted in the release of significant amounts of iron from ferritin and a marginal amount of iron in the presence of PG, CT, HQ, PL, PH or PD concentration and time-dependent increase in iron release from ferritin were observed although the increase was not linear as a function of time and concentration of the compounds studied. The presence of superoxide dismutase inhibited significantly the release of iron from ferritin by CT, HQ, PL, PH or PD. The iron released from ferritin by CT, HQ, PL, PH or PD enhanced lipid peroxidation in rat brain homogenate and released aldehydic products from bleomycin-dependent degradation of DNA and also caused single strand nicks to pUC18 DNA. These studies indicate that CT and HQ, the two principal polyphenolic metabolites of benzene and PL, PH or PD, the superoxide radical generating compounds were capable of reducing ferric iron from ferritin and also mobilizing and releasing iron from ferritin core. The release of iron from ferritin by these compounds is a result of direct reduction of ferritin iron by electron transfer and also reduction via superoxide radical. The release of iron from ferritin by CT and HQ may have toxicological implications in relation to benzene toxicity. The release of iron by superoxide radical generating agents suggests that oxidative stress may play a role as this could lead to disruption of intracellular iron homeostasis.

Borderline tuberculoid leprosy of the scalp

A case of borderline tuberculoid leprosy involving the hairy scalp is reported. To the best of our knowledge, only two paucibacillary leprosy patients with scalp lesion have been reported, and in only one was the scalp covered with hair.

Cardiovascular Responses to Scalp Infiltration with Different Concentrations of Epinephrine With or Without Lidocaine During Craniotomy

Intraoperative blood pressure changes alter cerebral blood flow in neurosurgical patients with impaired autoregulation. Infiltration of the scalp before craniotomy may cause hemodynamic changes that depend on the composition of the solution used. We investigated cardiovascular responses to infiltration of the scalp with five different combinations of epinephrine and lidocaine in 112 patients: Group A, lidocaine 0.5%; Group B, lidocaine 0.5% with epinephrine 1:200,000; Group C, lidocaine 0.5% with epinephrine 1:100,000; Group D, normal saline with epinephrine 1:200,000; and Group E, normal saline with epinephrine 1:100,000. Episodes of tachycardia occurred more frequently in group E (P = 0.03). Plain lidocaine did not cause any significant change in blood pressure. The incidence of systolic, diastolic, and mean arterial hypertension was significantly increased in group E (P < 0.01). Episodes of diastolic hypertension occurred more frequently in Group D (P < 0.01). A biphasic diastolic and mean arterial hypotension (around Minute 2 and Minutes 9-15) occurred in Groups C and B (P < 0.001). In conclusion, epinephrine 1:100,000 causes significant tachycardia. Epinephrine in concentrations of 1:100,000 and 1:200,000 causes significant hypertension. The combination of lidocaine and epinephrine attenuates the hypertension but results in a biphasic hypotensive response.

Onychocryptosis-phenol burn fiasco

Ingrowing toenails, onychocryptosis, are a common condition that can be treated conservatively or surgically. Conservative treatment often fails necessitating operative intervention. Surgical treatments include wedge resection, Zadik's procedure and nail removal with ablation of the germinal matrix by phenol. The following report describes a 15-year-old male footballer who sustained burns following phenol treatment, resulting in amputation of his left great toe, as well as suggestions to avoid any similar complications.

Pharmacokinetics of enrofloxacin and its metabolite ciprofloxacin after intramuscular administration of enrofloxacin in goats

The pharmacokinetics of enrofloxacin and its active metabolite ciprofloxacin were investigated in goats after a single intramuscular administration of enrofloxacin at 2.5 mg/kg body weight. The plasma concentrations of enrofloxacin and ciprofloxacin were determined simultaneously by a HPLC method. The peak concentrations (Cmax) of enrofloxacin (1.13 microg/ml) and ciprofloxacin (0.24 microg/ml) were observed at 0.8 and 1.2 h, respectively. The elimination half-life (t1/2beta), volume of distribution (Vd(area)), total body clearance (Cl(B)) and mean residence time (MRT) of enrofloxacin were 0.74 h, 1.42 L/kg, 1329 ml/h per kg and 1.54 h, respectively. The t1/2beta, area under the plasma concentration-time curve (AUC) and the MRT of ciprofloxacin were 1.38 h, 0.74 microg h/ml and 2.73 h, respectively. The metabolic conversion of enrofloxacin to ciprofloxacin was appreciable (36%) and the sum of the plasma concentrations of enrofloxacin and ciprofloxacin was maintained at or above 0.1 microg/ml for up to 4 h. Enrofloxacin appears to be useful for the treatment of goat diseases associated with pathogens sensitive to this drug.

A peptide inhibitor of HIV-1 protease using alpha, beta- dehydro residues: a structure based computer model

HIV-1 encodes an aspartic protease, an enzyme crucial to viral maturation and infectivity. It is responsible for the cleavage of various protein precursors into viral proteins. Inhibition of this enzyme prevents the formation of mature, infective viral particles and therefore, it is a potential target for therapeutic intervention following infection. Several drugs that inhibit the action of this enzyme have been discovered. These include peptidomimetic inhibitors such as ABT-538 and saquinavir, and structure based inhibitors such as indinavir and nelfinavir. Several of these have been tested in human clinical trials and have demonstrated significant reduction in viral load. However, most of them have been found to be of limited clinical utility because of their poor pharmacological properties and also because the viral protease becomes rapidly resistant to these drugs on account of mutations in the enzyme. One way to overcome these limitations is to design an inhibitor that interacts mainly with the conserved residues of HIV-1 protease. By a rational drug design approach based on the high resolution X-ray crystal structure of the HIV-1 protease with--MVT 101 (a substrate based inhibitor) and the specific design principles of peptides containing dehydro-Alanine (delta Ala) derived from our earlier studies, we have designed a tetrapeptide with the sequence: NH2-Thr-delta Ala-delta Ala-Gln-COOH. Energy minimization and molecular modelling of the interaction of the designed tetrapeptide with the inhibitor binding site indicate that the inhibitor is in an extended conformation and makes excessive contacts with the viral enzyme at the interface between the protein subunits. The designed inhibitor has 33% of its interaction with the conserved region of HIV-1 protease which is of the same order as that of MVT 101 with the enzyme.

Long-term follow up of multibacillary leprosy patients with high BI treated with WHO/MDT regimen for a fixed duration of two years

Forty-six, newly detected, previously untreated multibacillary (MB) patients with a bacterial index (BI) of > or = 3+ who had received WHO/MDT for 2 years were followed up for a total duration of 424 person-years and a mean duration of 9.26 +/- 2.98 years per patient. The BIs of the patients continued to fall, and all of the patients, except one, reached skin-smear negativity. WHO/MDT was well accepted and well tolerated. Relapse, which was defined as an increase in the BI of 1+ or more with or without clinical evidence of activity, was observed in only one patient, giving a relapse rate of 2.2% or 0.23 per 100 person-years in patients with a BI of > or = 3+ after long-term follow up. This patient was started on a second course of WHO/MDT to which he responded favorably. WHO/MDT for a fixed duration of 2 years for MB patients as recommended by the WHO is vindicated.

Radiosensitization of human breast cancer cells by a novel ErbB family receptor tyrosine kinase inhibitor

PURPOSE

Overexpression of the ErbB family of growth factor receptors is present in a wide variety of human tumors and is correlated with poor prognosis. The purpose of this study was to determine the effects of a novel small molecule ErbB tyrosine kinase inhibitor, CI-1033, in combination with ionizing radiation on breast cancer cell growth and survival.

MATERIALS & METHODS

Growth assays were performed on ErbB-overexpressing human breast cancer cells developed in our laboratory in the presence of 0.1-1.0 microM CI-1033 (Parke Davis). Clonogenic survival assays were performed in the presence of ionizing radiation with or without CI-1033. For some experiments, clonogen numbers, defined as the product of surviving fraction and total number of cells, were calculated at each time point during a course of multifraction radiation.

RESULTS

CI-1033 potently inhibited the growth of ErbB-overexpressing breast cancer cells. A single 48-h exposure of 1 microM CI-1033 resulted in growth inhibition for 7 days, whereas three times weekly administration resulted in sustained growth inhibition. Clonogenic survival was modestly decreased after a 7-day exposure to CI-1033. Exposure to both CI-1033 and radiation (6 Gy) yielded a 23-fold decrease in clonogenic survival compared to radiation alone. In a multifraction experiment, exposure to CI-1033 and three 5-Gy fractions of gamma radiation decreased the total number of clonogens in the population by 65-fold compared to radiation alone.

CONCLUSION

CI-1033 results in potent growth inhibition and modest cytotoxicity of ErbB-overexpressing breast cancer cells, and has synergistic effects when combined with ionizing radiation. These data suggest that CI-1033 may have excellent clinical potential both alone and in combination with radiation therapy.

Effects of endotoxin-induced fever and probenecid on disposition of enrofloxacin and its metabolite ciprofloxacin after intravascular administration of enrofloxacin in goats

Pharmacokinetics of enrofloxacin and its active metabolite ciprofloxacin were investigated in normal, febrile and probenecid-treated adult goats after single intravenous (i.v.) administration of enrofloxacin (5 mg/kg). Pharmacokinetic evaluation of the plasma concentration-time data of enrofloxacin and ciprofloxacin was performed using two- and one-compartment open models, respectively. Plasma enrofloxacin concentrations were significantly higher in febrile (0.75-7 h) and probenecid-treated (5-7 h) goats than in normal goats. The sum of enrofloxacin and ciprofloxacin concentrations in plasma > or =0.1 microg /mL was maintained up to 7 and 8 h in normal and febrile or probenecid-treated goats, respectively. The t1/2beta, AUC, MRT and ClB of enrofloxacin in normal animals were determined to be 1.14 h, 6.71 microg .h/mL, 1.5 h and 807 mL/h/kg, respectively. The fraction of enrofloxacin metabolized to ciprofloxacin was 28.8%. The Cmax., t1/2beta, AUC and MRT of ciprofloxacin in normal goats were 0.45 microg /mL, 1.79 h, 1.84 microg .h/mL and 3.34 h, respectively. As compared with normal goats, the values of t1/2beta (1.83 h), AUC (11.68 microg ? h/mL) and MRT (2.13 h) of enrofloxacin were significantly higher, whereas its ClB (430 mL/h/kg) and metabolite conversion to ciprofloxacin (8.5%) were lower in febrile goats. The Cmax. (0.18 microg /mL) and AUC (0.99 microg .h/mL) of ciprofloxacin were significantly decreased, whereas its t1/2beta (2.75 h) and MRT (4.58 h) were prolonged in febrile than in normal goats. Concomitant administration of probenecid (40 mg/kg, i.v.) with enrofloxacin did not significantly alter any of the pharmacokinetic variables of either enrofloxacin or ciprofloxacin in goats.