Bronchiectasis: causes and management

Bronchiectasis is a condition representing abnormal and permanent dilatation and distortion of medium sized bronchi, usually accompanied by destruction of the airway wall. Post inflammatory bronchiectasis remains very common in the developing countries as a sequel to pulmonary tuberculosis, whooping cough, and severe measles (among other causes). Cystic fibrosis is the most common cause of generalized bronchiectasis in developed countries. Symptoms primarily are chronic cough and expectoration of foul smelling sputum. Bronchography was, until recently, the investigation of choice for the diagnosis of bronchiectasis and the gold standard against which the current best imaging technique HRCT (high resolution computed tomography) has been compared. Treatment includes prompt attention to acute exacerbations, management of airway secretions and control of airway hyperreactivity. Treatment is aimed at the non progression of the disease and complete cure if possible. The role of surgical therapy has evolved from early curative resection for all patients to a more palliative approach. Patients with advanced generalized bronchiectasis should be considered for lung transplantation.

Phase I dose-escalation and pharmacokinetic study of temozolomide (SCH 52365) for refractory or relapsing malignancies

Temozolomide, an oral cytotoxic agent with approximately 100% bioavailability after one administration, has demonstrated schedule-dependent clinical activity against highly resistant cancers. Thirty patients with minimal prior chemotherapy were enrolled in this phase I trial to characterize the drug's safety, pharmacokinetics and anti-tumour activity, as well as to assess how food affects oral bioavailability. To determine dose-limiting toxicities (DLT) and the maximum tolerated dose (MTD), temozolomide 100-250 mg m(-2) was administered once daily for 5 days every 28 days. The DLT was thrombocytopenia, and the MTD was 200 mg m(-2) day(-1). Subsequently, patients received the MTD to study how food affects the oral bioavailability of temozolomide. When given orally once daily for 5 days, temozolomide was well tolerated and produced a non-cumulative, transient myelosuppression. The most common non-haematological toxicities were mild to moderate nausea and vomiting. Clinical activity was observed against several advanced cancers, including malignant glioma and metastatic melanoma. Temozolomide demonstrated linear and reproducible pharmacokinetics and was rapidly absorbed (mean Tmax approximately 1 h) and eliminated (mean t1/2 = 1.8 h). Food produced a slight reduction (9%) in absorption of temozolomide. Temozolomide 200 mg m(-2) day(-1) for 5 days, every 28 days, is recommended for phase II studies.

Absorption, metabolism, and excretion of 14C-temozolomide following oral administration to patients with advanced cancer

The purpose of this study is to characterize the absorption, metabolism, and excretion of carbon 14-labeled temozolomide (14C-TMZ) administered p.o. to adult patients with advanced solid malignancies. On day 1 of cycle 1, six patients received a single oral 200-mg dose of 14C-TMZ (70.2 microCi). Whole blood, plasma, urine, and feces were collected from days 1-8 and on day 14 of cycle 1. Total radioactivity was measured in all samples. TMZ, 5-(3-methyltriazen-1-yl)imidazole-4-carboxamide (MTIC), and 4-amino-5-imidazole-carboxamide (AIC) concentrations were determined in plasma, and urine and plasma samples were profiled for metabolite/degradation products. Maximum TMZ plasma concentrations were achieved between 0.33 to 2 h (mean, 1.2 h), and half-life, apparent volume of distribution, and oral clearance values averaged 1.9 h, 17 liters/m2, and 104 ml/min/m2, respectively. A first-order absorption, one-compartment linear model, which included first-order formation of MTIC from TMZ and elimination of MTIC via degradation to AIC, and a peripheral distribution compartment for AIC, adequately described the plasma TMZ, MTIC, and AIC concentrations. MTIC systemic clearance was estimated to be 5384 ml/min/m2, and the half-life was calculated to be 2.5 min. Metabolite profiles of plasma at 1 and 4 h after treatment showed that 14C-derived radioactivity was primarily associated with TMZ, and a smaller amount was attributed to AIC. Profiles of urine samples from 0-24 h revealed that 14C-TMZ-derived urinary radioactivity was primarily associated with unchanged drug (5.6%), AIC (12%), or 3-methyl-2,3-dihydro-4-oxoimidazo[5,1-d]tetrazine-8-carboxyl ic acid (2.3%). The recovered radioactive dose (39%) was principally eliminated in the urine (38%), and a small amount (0.8%) was excreted in the feces. TMZ exhibits rapid oral absorption and high systemic availability. The primary elimination pathway for TMZ is by pH-dependent degradation to MTIC and further degradation to AIC. Incomplete recovery of radioactivity may be explained by the incorporation of AIC into nucleic acids.

Phase I study of temozolomide in paediatric patients with advanced cancer. United Kingdom Children's Cancer Study Group

A phase I study of temozolomide administered orally once a day, on 5 consecutive days, between 500 and 1200 mg m(-2) per 28-day cycle was performed. Children were stratified according to prior craniospinal irradiation or nitrosourea therapy. Sixteen of 20 patients who had not received prior craniospinal irradiation or nitrosourea therapy were evaluable. Myelosuppression was dose limiting, with Common Toxicity Criteria (CTC) grade 4 thrombocytopenia occurring in one of six patients receiving 1000 mg m(-2) per cycle, and two of four patients treated at 1200 mg m(-2) per cycle. Therefore, the maximum-tolerated dose (MTD) was 1000 mg m(-2) per cycle. The MTD was not defined for children with prior craniospinal irradiation because of poor recruitment. Plasma pharmacokinetic analyses showed temozolomide to be rapidly absorbed and eliminated, with linear increases in peak plasma concentrations and systemic exposure with increasing dose. Responses (CR and PR) were seen in two out of five patients with high-grade astrocytomas, and one patient had stable disease. One of ten patients with diffuse intrinsic brain stem glioma achieved a long-term partial response, and a further two patients had stable disease. Therefore, the dose recommended for phase II studies in patients who have not received prior craniospinal irradiation or nitrosoureas is 1000 mg m(-2) per cycle. Further evaluation in diffuse intrinsic brain stem gliomas and other high-grade astrocytomas is warranted.

Single-dose pharmacokinetics of isepamicin in young and geriatric volunteers

Isepamicin is a new aminoglycoside antibiotic with activity against both gram-negative and gram-positive bacteria. The pharmacokinetics of isepamicin were evaluated after a 0.5-hour intravenous infusion of alpha 15-mg/kg dose to groups of young adults and geriatric volunteers. Isepamicin was safe and well tolerated. No adverse events related to the infusion were reported. As age increased, there were increases in the elimination phase half-life (t1/2 beta) and the area under the plasma concentration-time curve extrapolated to infinity (AUC0-infinity), and decreases in systemic (Cl) and renal clearance (Clr). The changes seen in Cl with age were a result of changes in renal function estimated by creatinine clearance (Clcr). There were no apparent correlations between age and maximum plasma concentration (Cmax), half-life of the tau-phase (t1/2 tau), volume of distribution at steady-state (Vdss), or the amount of isepamicin excreted in urine within 24 hours after dose administration (Ae24 hrs). When comparing the elderly (61-80 years old) with the younger (21-60 years) volunteers, the (AUC0-infinity), and t1/2 beta values were higher in the elderly and the Cl and Clr values were lower, but Cmax, t1/2 tau and Vdss were similar in the two age groups. The contribution of the tau-phase to the overall AUC was minimal and similar for the two age groups. Also, there were no gender effects on the pharmacokinetics of isepamicin in both the young and elderly volunteers. These results demonstrate that changes in the pharmacokinetics of isepamicin in the elderly are attributable to changes in renal function, whereas age, per se, is not a significant factor.

Pharmacokinetics of isepamicin following a single administration by intravenous infusion or intramuscular injections

The pharmacokinetics of isepamicin following administration of a 1-g dose were evaluated for 18 healthy male volunteers between the ages of 26 and 38. In a randomized crossover fashion, each volunteer received doses of isepamicin by a 30-min intravenous infusion and as an intramuscular injection. Blood samples were collected at specified times after dosing and assayed for isepamicin by a validated radioimmunoassay method. The individual plasma concentration-time curves were analyzed by noncompartmental methods. In general, the pharmacokinetics after intravenous infusion and intramuscular injection were similar. As expected, the maximum concentration of isepamicin in serum following intramuscular injection (37.2 microg/ml) was lower than the observed concentration at the end of infusion (66.7 microg/ml). The areas under the concentration-time curves from 0 h to infinity following intramuscular and intravenous administration were 164.8 and 154.5 microg x hr/ml, respectively, indicating complete absorption following intramuscular administration. The respective mean terminal-phase half-life (t1/2) values were 2.6 and 3.6 h. Although t1/2 was slightly longer following intravenous infusion, the small difference in the observed t1/2 values was not considered to be clinically significant. Total body clearances following intramuscular injection and intravenous infusion were 1.3 and 1.4 ml/min/kg, respectively, which were similar to renal serum creatinine clearances in healthy volunteers (> 1.14 ml/min/kg). The drug was safe and well tolerated. The results of the present study clearly show complete absorption of isepamicin following intramuscular administration. The similarity in the pharmacokinetics after intravenous infusion and intramuscular dosing would permit interchangeable administration of isepamicin by either route without compromising clinical efficacy.

Comparative efficacy of jet nebulizer and metered dose inhaler with spacer device in the treatment of acute asthma

OBJECTIVE

To compare the relative efficacy of jet nebulizer and metered dose inhaler (MDI) with spacer for the administration of aerosolized salbutamol in an acute exacerbation of bronchial asthma.

DESIGN

Randomized prospective study.

SETTING

Emergency Room.

METHODS

In 60 subjects with acute asthma aged between 1 to 12 years, clinical and laboratory assessment of severity at recruitment included heart rate, respiratory rate, pulsus paradoxus, arterial blood gas analysis (all cases) and peak expiratory flow rate (wherever possible). The subjects were randomized into two equal groups to receive aerosolized salbutamol either via nebulizer (Group I) or MDI-spacer (Group II) as per the Consensus Guidelines. The response to therapy was sequentially assessed after 20, 40 and 60 minutes of institution of therapy.

RESULTS

A significantly (p < 0.02) greater number of subjects in Group II presented with severe dyspnea and intercostal muscle retraction (subjective assessment). However, the objectively evaluable outcome parameters were comparable (p > 0.05) in both groups at presentation. All the outcome measures showed a significant (p < 0.05) improvement with time in both the groups. The recovery parameters were comparable (p > 0.05) at different time periods in the two groups.

CONCLUSION

MDI-spacer is as effective as a nebulizer for the aerosolized administration of salbutamol in an acute exacerbation of asthma in children. However, for developing countries, distinct advantages (economic and power requirement) argue strongly for utilization of MDI-spacer in preference to nebulizer.

Induction of anergy in CD8 T cells by B cell presentation of antigen

Induction of T cell anergy is thought to occur during activation in the absence of adequate costimulation. Here we demonstrate induction of anergy in a CD8 T cell clone by its cognate Ag in the presence of B7-1 and B7-2 costimulation. Primary activation of a CD28+CD8+ T cell clone by either human T cell lymphotrophic virus type I (HTLV-I) Tax11-19 peptide-pulsed EBV-transformed B cells, CD40L-stimulated B cells, or T cells was sufficient to induce complete unresponsiveness to a secondary Ag challenge. This was not caused by lack of B7 costimulation since the APCs expressed B7-1 and B7-2 and failed to induce anergy in an MBP peptide 84-102-reactive CD4 T cell clone. While anergic CD8 T cells did not proliferate, they retained their ability to lyse peptide-pulsed target cells. However, Ag stimulation failed to induce IL-2 mRNA transcription and IL-2 secretion, although immediate early tyrosine phosphorylation was normal and anti-CD3 cross-linking induced identical levels of CD40L expression in anergized and non-anergized CD8 T cells. Secondary Ag stimulation in the presence of exogenous IL-2, however, resulted in normal proliferative response. Moreover, while stimulation of CD8 T cells with PHA and B cells induced anergy, CD8 T cell stimulation with PHA and mononuclear cells failed to do so. In addition, the presence of mononuclear cells during the exposure of CD8 T cells to peptide-pulsed B cells prevented the induction of anergy. Together, our observations demonstrate that at least a subpopulation of CD8 T cells are anergized when costimulation is provided by B cells or T cells.

Induction of anergy in CD8 T cells by B cell presentation of antigen

Induction of T cell anergy is thought to occur during activation in the absence of adequate costimulation. Here we demonstrate induction of anergy in a CD8 T cell clone by its cognate Ag in the presence of B7-1 and B7-2 costimulation. Primary activation of a CD28+CD8+ T cell clone by either human T cell lymphotrophic virus type I (HTLV-I) Tax11-19 peptide-pulsed EBV-transformed B cells, CD40L-stimulated B cells, or T cells was sufficient to induce complete unresponsiveness to a secondary Ag challenge. This was not caused by lack of B7 costimulation since the APCs expressed B7-1 and B7-2 and failed to induce anergy in an MBP peptide 84-102-reactive CD4 T cell clone. While anergic CD8 T cells did not proliferate, they retained their ability to lyse peptide-pulsed target cells. However, Ag stimulation failed to induce IL-2 mRNA transcription and IL-2 secretion, although immediate early tyrosine phosphorylation was normal and anti-CD3 cross-linking induced identical levels of CD40L expression in anergized and non-anergized CD8 T cells. Secondary Ag stimulation in the presence of exogenous IL-2, however, resulted in normal proliferative response. Moreover, while stimulation of CD8 T cells with PHA and B cells induced anergy, CD8 T cell stimulation with PHA and mononuclear cells failed to do so. In addition, the presence of mononuclear cells during the exposure of CD8 T cells to peptide-pulsed B cells prevented the induction of anergy. Together, our observations demonstrate that at least a subpopulation of CD8 T cells are anergized when costimulation is provided by B cells or T cells.

Calcium blockage in pulmonary hypertension and hypoxic vasoconstriction

Both extracellular and intracellular calcium (Ca2+) play important roles in hypoxic pulmonary vasoconstriction (HPV) and the vasoconstrictor responses to endogenous pulmonary vasoconstrictor substances, as evidenced by the effect of calcium-channel blockers on these vasoconstrictor responses and the measurement of changes in Ca2+ flux or intracellular Ca2+ concentrations in isolated cells. The more vasoselective the calcium-channel blocker, the greater its effect on pulmonary vasoconstriction. However, these drugs are not selective for the pulmonary vascular bed and are not as potent as pulmonary vasodilators when compared with other vasodilator drugs, including prostaglandin E1, isoproterenol, prostacyclin, or nitroglycerin. Moreover, the primary effect of vasoselective calcium-channel blockers on pulmonary vascular resistance is secondary to the effects of these agents on systemic vascular resistance and cardiac output. Although there is improvement in oxygen delivery, exercise tolerance, and survival in patients with primary pulmonary hypertension who respond to calcium-channel blockers, the response of individual patients to these drugs is difficult to predict because the extent of reversible versus irreversible changes in the pulmonary vasculature is not known. The use of these drugs in patients with chronic hypoxia-induced pulmonary vasoconstriction may be associated with a worsening of ventilation-perfusion mismatching secondary to inhibition of HPV.

Epidemiology of chronic suppurative otitis media and deafness in a rural area and developing an intervention strategy

Of 613 children evaluated in a village in Haryana 94 (15.3%) were observed to have chronic suppurative otitis media (CSOM). Fifty eight (61.7%) children had hearing impairment. CSOM contributed to 71.6% of the hearing impaired (58/81). On analysis of association of CSOM with literacy and socio-economic status of mothers, and age, sex, and upper respiratory tract infections (URI) in children positive correlation was observed only with URIs (P < 0.001). Literacy and socio-economic status of the mothers did not correlate significantly with knowledge about treatment seeking, and ear cleaning practices, probably due to the narrow range of incomes and literacy levels. An intervention program consisting of play, demonstrations, health charts and slogans, and aural cleaning and antibiotic drops was introduced.

Pharmacokinetics and metabolism of 14C-isepamicin in humans following intravenous administration

Twelve healthy adult male volunteers received 1 g (base equivalent) of 14C-isepamicin (131 microCi) as an intravenous bolus over 5 min. The areas under the plasma concentration-time curves at infinity for isepamicin (196 micrograms*h/ml) and total radioactivity (164 micrograms*h/ml) were similar, indicating no biotransformation of isepamicin. The disappearance of isepamicin from plasma followed a triexponential decline, with half-lives of 0.17, 2.12, and 34 h for the alpha, beta, and gamma phases, respectively. However, the contribution of the gamma phase to the total area under the concentration-time curve was only 2.6%. There were no detectable metabolites in plasma and urine, confirming that isepamicin was not biotransformed. The cumulative levels of isepamicin and total radioactivity excretion in urine from 0 to 120 h were 97.3 and 92.1% of the dose, respectively, indicating that the drug was excreted mainly as unchanged isepamicin in urine.

Pharmacokinetic-pharmacodynamic (PK-PD) modeling for a new antihypertensive agent (neutral metalloendopeptidase inhibitor SCH 42354) in patients with mild to moderate hypertension

SCH 42354, a neutral metalloendopeptidase (NEP) inhibitor, is the pharmacologically active form of the prodrug SCH 42495. It exerts antihypertensive effects by potentiating atrial natriuretic peptide (ANP) activity through inhibition of its hydrolysis by NEP. The objective of this study was to characterize the pharmacokinetics (PK) and pharmacodynamics (PD) of SCH 42354 in hypertensive males. SCH 42495 12.5 to 400 mg was administered orally to hypertensive men twice daily in a double-blind, placebo controlled multiple-dose parallel group design. Plasma SCH 42354 concentration and diastolic blood pressure (DBP) data were used to develop a PK-PD model using two approaches. In the first (non-integrated) approach, the ¿link¿ model was used to predict effect-site concentrations, and was applied to data obtained at the 300 and 400 mg BID doses only; data at the other (lower) doses were not amenable to modeling because of high variability. Effect-site concentration and DBP data were then fit to a sigmoid Emax PD model. For the 300 mg BID dose, PD parameters were: maximum effect (Emax), 8.1 mmHg; no-drug effect (Eo), 3.6 mmHg; concentration corresponding to 50% of maximum response (EC50), 0.87 microgram x ml(-1); and gamma, 3.9. In the second (time-integrated) approach, plasma SCH 42354 concentration and effect data obtained over the entire dose range were integrated with respect to time. Average plasma concentration and DBP data were then fit to a simple Emax PD model. PD parameters obtained over the dose range were: Emax, 10.3 mmHg; Eo, 2.0 mmHg; and EC50 0.7 microgram x ml(-1). These were similar to the estimates obtained from the first approach, demonstrating that the integrated (average) data allow PK-PD modeling over the (entire) dose range. The analysis showed that, at steady-state, a 400 mg BID dose of SCH 42495 produced an approximate 10 mmHg decrease in DBP in hypertensive males; the average plasma SCH 42354 concentration attained at this dose was approximately 1.8 microgram x ml(-1).

Pharmacokinetics of ceftibuten in children

The bioavailability and pharmacokinetics of ceftibuten administered as an oral suspension were characterized by several studies in young healthy male adults (19 to 39 years old) and children ranging in age from 6 months to 17 years. Ceftibuten suspension was found to be bioequivalent and thus interchangeable with a standard 400-mg capsule. As with the capsule formulation, food slightly (< 20%) affected the rate and extent of absorption of the suspension. The recommended dose of 9.0 mg/kg was found to produce comparable plasma concentrations in children of all ages (6 months to 17 years). The range of mean values of maximum plasma concentrations (Cmax) was 12 to 16 micrograms/ml at the 9.0-mg/kg dose level. Doses of 4.5, 9.0 and 13.5 mg/kg produced Cmax and area under the plasma concentration-time curve values that were dose-proportional. The half-life (t1/2) was essentially independent of age and dose, ranging from 2 to 3 hours. The apparent clearance (Cl/F), uncorrected for the fraction of drug absorbed (F), is independent of dose but appears to increase with a decrease in age. This also occurs to a lesser degree with the volume of distribution (Vd/F), uncorrected for F. Current evidence suggests that this is more likely to be caused primarily by a decrease in F than an increase in Cl. Ceftibuten rapidly and extensively reaches the middle ear fluid in children with acute otitis media. Within 4 hours concentrations in middle ear fluid are similar to plasma concentrations and can be measured for 12 hours. The ratio of area under the concentration time curve for middle ear fluid relative to plasma was about 70%.(ABSTRACT TRUNCATED AT 250 WORDS)

Differential activation of proliferation and cytotoxicity in human T-cell lymphotropic virus type I Tax-specific CD8 T cells by an altered peptide ligand

Human T-cell leukemia virus type I (HTLV-I) gives rise to a neurologic disease known as HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Although the pathogenesis of the disease is unknown, the presence of a remarkably high frequency of Tax-specific, cytotoxic CD8 T cells may suggest a role of these cells in the development of HAM/TSP. Antigen-mediated signaling in a CD8 T-cell clone specific for the Tax(11-19) peptide of HTLV-I was studied using analog peptides substituted in their T-cell receptor contact residues defined by x-ray crystallographic data of the Tax(11-19) peptide in the groove of HLA-A2. CD8 T-cell stimulation with the wild-type peptide antigen led to activation of p56lck kinase activity, interleukin 2 secretion, cytotoxicity, and clonal expansion. A Tax analog peptide with an alanine substitution of the T-cell receptor contact residue tyrosine-15 induced T-cell-mediated cytolysis without activation of interleukin 2 secretion or proliferation. Induction of p56lck kinase activity correlated with T-cell-mediated cytotoxicity, whereas interleukin 2 secretion correlated with [3H]thymidine incorporation and proliferation. Moreover, Tax peptide analogs that activated the tyrosine kinase activity of p56lck could induce unresponsiveness to secondary stimulation with the wild-type peptide. These observations show that a single amino acid substitution in a T-cell receptor contact residue of Tax can differentially signal CD8 T cells and further demonstrate that primary activation has functional consequences for the secondary response of at least some Tax-specific CD8 T cells to HTLV-I-infected target cells.

Tone-dependent responses of histamine in feline pulmonary vascular bed

Under conditions of controlled pulmonary blood flow and constant left atrial pressure, histamine produced tone-dependent responses in the pulmonary vascular (PV) bed of intact-chest, spontaneously breathing cats. At low, baseline PV tone, histamine produced dose-dependent increases in mean lobar arterial pressure that were antagonized by the selective histamine H1-receptor antagonist, diphenhydramine. The cyclooxygenase inhibitor, meclofenamate, and the thromboxane A2 (TxA2) receptor antagonist, SQ-29548, had no effect on these vasoconstrictor responses of histamine. After an increase in PV tone with an intralobar arterial infusion of a TxA2 mimic, U-46619, histamine produced vasodilator responses at low doses, biphasic vasodilator/vasoconstrictor responses at midrange doses, and vasoconstrictor responses at high doses. Diphenhydramine antagonized vasoconstrictor responses and the vasodilator responses of low to midrange doses and enhanced vasodilator responses of high doses of histamine at elevated PV tone. Selective H2-receptor antagonists, ranitidine and meclofenamate, and selective H3-receptor antagonist, thioperamide, did not antagonize vasodilator responses of histamine. H1- and H2-receptor antagonism was more effective in reducing the vasodilator responses of histamine at elevated PV tone than H1-receptor antagonism alone. These data support that histamine produces vasoconstrictor responses at low baseline and elevated PV tone by acting on H1 receptors that do not induce the release of vasoconstrictor prostanoids. At elevated PV tone, histamine produces vasodilation by acting on H1 receptors that are not coupled to the release of vasodilator prostaglandins and also, in part, by acting on H2 receptors.

Sustained release of ferrous sulfate from polymer-coated gum arabica pellets

Sustained release of ferrous sulfate (FeSO4) from gum arabica pellets has been achieved for 7 h. Release is further sustained for 12 to 600 h by coating the pellets with polyvinyl acetate and ethylene vinyl acetate, respectively. An increase in the amount of gum arabica in the pellets decreases the rate of release due to the gelling property of gum arabica. The gel layer acts as a barrier and retards the rate of diffusion of FeSO4 through the pellet. In coated pellets, an increase in thickness of membrane helps to sustain the release of FeSO4 for a longer duration. Thus, the release of FeSO4 can be sustained for the required duration by adjusting the amount of gum arabica in the pellet and the composition and thickness of polymeric coat. The mechanism of release accordingly varies from Fickian to zero-order and super case II transport.

Paraganglioma of the cauda equina

A case of paraganglioma of the cauda equina is presented. Usually reported to be benign with good prognosis, the present patient had a somewhat different course. The behaviour of the tumour was unusual, with rapid recurrence seen within first month of surgery. The need for total surgical excision and role of adjuvant radiotherapy is highlighted.

Intergeneric hybridization between Diplotaxis siifolia, a wild species and crop brassicas

Attempts were made to obtain intergeneric hybrids between Diplotaxis siifolia, a wild species, and cultivars of Brassica (B. campestris, B. juncea, and B. napus). The crosses showed unilateral incompatibility. When the wild species was used as female parent, pollen germination and pollen tube growth were normal, but hybrid seeds aborted due to post-fertilization barriers. Reciprocal crosses (cultivars as female parent) showed strong pre-fertilization barriers; although pollen grains showed germination, pollen tubes failed to enter the stigma. Hybrids were realized in two of the crosses, D. siifolia x B. juncea and D. siifolia x B. napus, through ovary culture. The hybrids were multiplied in vitro by multiplication of axillary shoots, or somatic embryogenesis. Detailed studies were carried out on the hybrid D. siifolia x B. juncea. F1 hybrids had shrivelled anthers and were pollen sterile. Amphiploids of this hybrid showed 60% pollen fertility and produced seeds upon self-pollination as well as backcross pollination with the pollen of B. juncea.

Comparative pharmacokinetics of 14C-piperacillin following intravenous and intraperitoneal administration in pregnant and non-pregnant rats

14C-piperacillin (Pipracil) at a dose level of 1000 mg/kg was administered intravenously or intraperitoneally to pregnant and non-pregnant female rats. Rats were sacrificed at predetermined time intervals, and 14C-piperacillin concentrations determined in serum, amniotic fluid, placenta, and fetus. The piperacillin serum levels in both pregnant and nonpregnant rats following intravenous administration were comparable; however, following intraperitoneal administration, the serum drug levels in the pregnant rats as compared to the nonpregnant rats were lower. The fetal drug levels, however, were higher following intraperitoneal administration than following intravenous administration. The total area under the fetal drug concentration-time curve following intraperitoneal administration was about two times the corresponding area under the curve following intravenous administration. The data indicate that the fetal exposure to piperacillin was greater following intraperitoneal administration.