Sol-gel silica laser tunable in the blue

Doped and undoped silica slabs were fabricated through the use of the sol-gel technique. Extended UV transmission was observed for HCl-catalyzed sol-gel silica. Under transverse pumping with a XeCl laser, narrow-linewidth (<0.9-nm) laser oscillation from silica slabs doped with coumarin 460 (C460) was achieved in a grating-resonator cavity configured in the grazing-indicence geometry. Tuning of the C460-doped silica laser extended from 468 to 494 nm. The conversion efficiency of the narrow-linewidth blue laser was 5.5%.

The advantageous use of hypoxic tumour cells in cancer therapy: identical chemosensitization by metronidazole and misonidazole at moderately elevated temperatures

Chemosensitization by two nitroimidazoles (NIs), metronidazole (METRO) and misonidazole (MISO), of the anti-tumour effect of alkylating agents was studied at three different temperatures: room temperature (RT), 37 and 41.5 degrees C. Three alkylating agents, cyclophosphamide (CY), 1,3 bis(2-chloroethyl)-N-nitrosourea (BCNU) and melphalan (L-PAM) were tested when the tumours reached an average diameter of 4 mm. Tumours were 4th generation isotransplants of a spontaneous fibrosarcoma, FSa-II. Treatment at 37 or 41.5 degrees C was given by immersing the tumour-bearing foot for 60 min in a water bath set at these temperatures. The test agents were injected ip immediately before immersing the foot in the water bath, whereas METRO or MISO (2.5 mmol/kg) was given ip 30 min before the injection of a test agent. Following treatment the tumour growth (TG) time, i.e. the time required for one-half of treated tumours to reach 1000 mm3 after the treatment day, was studied. For CY, MISO was a better sensitizer than METRO at RT and 37 degrees C, but the magnitude of the chemosensitization by MISO and METRO became identical at 41.5 degrees C. Notably, the chemosensitization was substantially enhanced at 41.5 degrees C, whereas neither 41.5 degrees C-heat, NIs or combined NI and heat prolonged the TG time. Although no chemosensitization was observed for BCNU at RT, both METRO and MISO equally enhanced the effect of BCNU at 41.5 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)

A reduced dose approach to hepatitis B vaccination for low-risk newborns and preschool children

The effectiveness of a 2.5 micrograms dose of the hepatitis B vaccine (B-Hepavac II) was compared with that of 5 micrograms in 587 low-risk neonates and 777 preschool children of age 3-8 years. The vaccines were administered at months 0, 1 and 3, with postvaccination serology tested at months 4 and 12. The seroconversion rates of the 2.5 microgram recipients (newborn: 93.5%; preschool children: 97.4%) are comparable with the 5 micrograms group (newborn: 95.7%; preschool children: 98.7%). The seroconversion rates of the newborns are, however, significantly lower in the 2.5 micrograms group if positive response is taken as a titre > 10 IU l-1, instead of > 0 IU l-1. The older children, on the other hand, achieved a higher seroconversion rate and geometric mean titre (GMT) when compared with the newborns. irrespective of the dose received.

Profile of opportunistic infections among HIV-1 infected people in Hong Kong

BACKGROUND

To determine the spectrum of opportunistic infections in patients with human immunodeficiency virus (HIV-1) infection in Hong Kong.

METHODS

A retrospective study of 214 HIV-1-infected patients, seen between December 1984 and December 1993 in a specialist clinic for HIV/AIDS:

RESULTS

A majority (94%) of the patients in the cohort were male; 84% had acquired HIV via sexual contacts. Two-thirds were ethnic Chinese. Ninety-two (43%) had developed AIDS, and 54(25%) had presented with other non AIDS-defining opportunistic infections during the study period. The primary AIDS defining illnesses of 80 patients were infections: Pneumocystis carinii pneumonia (50%), extrapulmonary tuberculosis (10%) and cytomegalovirus (CMV) disease (8%). Opportunistic infections among Chinese and non-Chinese were similar in spectrum, though higher frequencies of infection with CMV, Mycobacterium avium intracellulare and tuberculosis were seen among Chinese, whereas the opposite was true for Pneumocystis carinii pneumonia, toxoplasmosis and cryptosporidiosis. Disseminated Penicillium marneffei infection was another significant disease for HIV-positive patients. Common non AIDS-defining opportunistic infections included herpes zoster, oral candidiasis, herpes simplex infection and genital/anal wart. The median CD4 count at HIV diagnosis for AIDS patients was much lower than non-AIDS patients (147 vs 546/ul). Survival of deceased AIDS patients was poor, with a median of only five months. Survival has however, apparently, improved over the recent years.

CONCLUSIONS

In Hong Kong, Pneumocystis carinii pneumonia remained the most common primary AIDS event, while Penicillium marneffei was emerging as another significant cause of major infection. Herpes zoster and oral candidiasis were the two most frequently encountered minor opportunistic infections.

M3 muscarinic receptors on murine HSDM1C1 cells: further functional, regulatory, and receptor binding studies

In the present studies, the pharmacology and regulation of the functional muscarinic receptors on HSDM1C1 cells were probed using phosphoinositide (PI) turnover assays. In addition, the receptor binding of the putative M3-selective radioligand, [3H]4-DAMP, to cell homogenates was characterized. Carbachol (EC50 = 9 microM), (+)muscarine (EC50 = 4.5 microM) and cis-dioxolane (EC50 = 0.72 microM) were full agonists which stimulated PI turnover by 13.3 +/- 1.0 fold above basal values. The potencies of numerous agonists in this assay system were relatively similar to their affinities in receptor binding assays. Exposure of HSDM1C1 cells to 10 nM-10 microM muscarine during the last 24h of [3H]myo-inositol-labeling resulted in a concentration-dependent reduction in the cis-dioxolane affinity and maximal PI response induced by subsequent treatment with cis-dioxolane. Pertussis toxin (5-2000 ng/ml) caused a partial reduction in the cis-dioxolane-induced PI turnover. Likewise, exposure of the HSDM1C1 cells to an active phorbol ester (TPA) resulted in a partial inhibition of the cis-dioxolane-induced (100 microM) PI turnover. The half-maximal effect of TPA was produced at 1.8 +/- 0.3 nM. [3H]4-DAMP binding to cell homogenates was of high affinity (Kd = 0.19 +/- 0.04 nM) and moderate capacity (Bmax = 201 +/- 22 fmol/mg protein). The pharmacological specificity (4-DAMP > p-FHHSiD > dicyclomine > pirenzepine > methoctramine > AFDX-116 > gallamine) resembled that for [3H]NMS binding and correlated well with that observed for inhibition of PI turnover. These studies further support the identification of M3 receptors on HSDM1C1 cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Utility of complement fixation and microimmunofluorescence assays for detecting serologic responses in patients with clinically diagnosed psittacosis

The serodiagnosis of human psittacosis was considerably improved by a microimmunofluorescence (MIF) assay that uses selected strains of Chlamydia psittaci, C. pneumoniae, and C. trachomatis as antigens. The 78 patients examined in the study were clinically diagnosed as having psittacosis on the basis of compatible clinical symptoms following exposure to sick birds. The conventional complement fixation (CF) test identified 36 patients, or 46% (36 of 78) of the total, as positive. Antibody responses to C. psittaci were demonstrated by the MIF test in all 36 CF-positive patients. The MIF test also detected antibody responses to C. psittaci in 12 patients (15% of the total) whose sera were negative or anticomplementary in the CF test. Seven patients, or 9% (7 of 78) of the total, were identified by the MIF test as having C. pneumoniae infections. About 30% of the study patients (23 of 78) showed no serologic evidence of either C. psittaci or C. pneumoniae infection by both the CF and the MIF tests. Four distinctive serologic reaction patterns were observed in the study patients. Recognition of these reaction patterns and judicious corroboration of serologic responses to the chlamydial species by the MIF test with epidemiologic and clinical information will increase the efficiency and accuracy of serodiagnosis for human psittacosis.

Radiographic appearance of Chlamydia pneumoniae (TWAR strain) respiratory infections. CBPIS Study Group. Community-based Pneumonia Incidence Study

PURPOSE

To report the spectrum of radiographic findings associated with a new respiratory pathogen: Chlamydia pneumoniae (TWAR strain).

MATERIALS AND METHODS

Radiographs of 55 adult patients hospitalized with serologic evidence of C pneumoniae were retrospectively reviewed.

RESULTS

On the basis of serologic criteria, two types of acute respiratory infection are possible: primary (first exposure) infections and recurrent, acute infection in a previously exposed individual. In the primary group, alveolar opacities (65%) with a unilateral distribution (71%) were most common at admission. Cavitary disease and hilar or mediastinal lymphadenopathy were uncommon. Small to medium-sized pleural effusions were common in both primary and recurrent groups during hospitalization. Also, both groups tended to progress to bilateral, mixed, interstitial and alveolar changes during the course of infection.

CONCLUSION

Different radiographic patterns exist for the two types of acute C pneumoniae infection.

Condom use among female commercial sex workers and male clients in Hong Kong

The use of condoms is an aid to protection against human immunodeficiency virus (HIV) infection and other sexually transmitted diseases (STDs). In a one-and-a-half month period in mid-1993, 190 commercial female sex workers and 633 male clients of 8 Social Hygiene Clinics in Hong Kong were interviewed on their practice in condom usage. For both sex workers and clients, 18.5% and 22.8% never and 55.3% and 50.3% seldom used condoms during sexual contacts with paying partners and non-paying partners respectively. The majority (86%) of male clients claimed that they would use a condom if they knew it could reduce risk of contracting HIV and other STD. Condom promotion activities are necessary, particularly for those at higher risk of infection because of their sexual behaviour.

Beta 1-adrenergic and dopamine (D1)-receptors coupled to adenylyl cyclase activation in GT1 gonadotropin-releasing hormone neurosecretory cells

Binding sites labeled by the beta-adrenergic receptor radioligand (-)-[125I]iodocyanopindolol ([125I]ICYP) and the selective D1-subtype dopamine (DA) receptor radioligand (+)-[125I]SCH 23982 were identified on immortalized hypothalamic GnRH neurons (GT1-7 cell lines). Saturation analyses in crude particulate suspensions of GT1 cells described high affinity and low capacity binding sites for [125I]ICYP (Kd, 41 pM; binding capacity, 25 fmol/mg protein) and [125I]SCH 23982 (Kd, 320 pM; binding capacity, 23 fmol/mg protein). These binding sites were further characterized in competition assays using a variety of agonists and antagonists selective for either beta-adrenergic or DA receptor subtypes. The pharmacological profiles of [125I]ICYP and [125I]SCH 23982 binding obtained from these studies indicated that the radioligands were labeling beta 1-adrenergic and D1-dopaminergic receptor sites, respectively. Northern blot analyses of purified GT1 cell mRNA documented the expression of D1-dopaminergic and beta 1-adrenergic receptor mRNAs. beta 2-Adrenergic receptor mRNA was not identified. All three transcripts were detected in mouse brain mRNA. Both beta 1-adrenergic and D1-receptors were discovered to be positively coupled to adenylyl cyclase. DA and the beta-adrenergic agonist isoproterenol each provoked a rapid and marked stimulation of adenylyl cyclase activity in GT1 cell membrane suspensions. Subtype-selective beta-adrenergic and DA receptor antagonists were used to inhibit isoproterenol- and DA-stimulated adenylyl cyclase activities. Their relative potencies indicated that the isoproterenol stimulation was mediated via the beta 1-adrenergic receptor. The DA-stimulated adenylyl cyclase activity was mediated via the D1-DA receptor. These studies have identified functional beta 1-adrenergic and D1-dopaminergic receptors positively coupled to adenylyl cyclase on GT1 GnRH neurosecretory cells. The existence of these receptors suggests that the noradrenergic and dopaminergic regulation of gonadotropin secretion may be mediated at least in part via direct synapses on GnRH neurons.

Comparative study of thermoradiosensitization by misonidazole and metronidazole in vivo: antitumour effect and pharmacokinetics

Tumour control by local hyperthermia (43.5 degrees C, 30 min) and radiation (20 Gy) given in combination with misonidazole (MISO) or metronidazole (METRO) was studied using FSa-II murine fibrosarcoma. When MISO or METRO (5 mmol/kg) was given 30 min before heat and subsequently treated with radiation, tumour regression was observed for both agents. Radiation dose-response curves for MISO and METRO with heating at 43.5 degrees C for 30 min were identical. Mouse foot reaction was used to evaluate local toxicity following combined heat, a nitroimidazole and radiation treatment. MISO enhanced the magnitude of foot reaction and prolonged the recovery time compared with heat plus radiation controls. There were no observable differences of foot reaction between animals treated with heat plus radiation and those animals treated with heat, radiation and METRO. Pharmacokinetics of the nitroimidazoles heated at 43.5 degrees C for 30 min in FSa-II tumours were investigated as a possible mechanism of thermal sensitization. Local hyperthermia did not alter the pharmacokinetics of METRO. Tumour concentration and tumour/plasma ratio of MISO were slightly decreased during heating. Since the hypoxic metabolism of the nitroimidazoles did not increase significantly during the heat treatment, the thermal enhancement of MISO or METRO radiosensitization cannot be explained by the increase in hypoxic cytotoxicity of the nitroimidazoles at elevated temperature alone. The two nitroimidazoles also were not accumulated in the tumour after heating. Therefore, alternation of pharmacokinetics is not the major mechanism for the thermal enhancement of nitroimidazole radiosensitization. The METRO radiosensitization effect became identical to that of MISO at elevated temperatures is of particular importance in clinical radiosensitization. The very low local and systemic toxicity together with the high efficacy of METRO at elevated temperatures will make it an attractive candidate as a future clinical radiosensitizer.

Efficient culture of Chlamydia pneumoniae with cell lines derived from the human respiratory tract

Two established cell lines, H 292 and HEp-2, originating from the human respiratory tract, were found to be significantly more efficient and practical than the currently used HeLa 229 cells for growth of Chlamydia pneumoniae. Six strains of C. pneumoniae recently isolated from patients with respiratory ailments were used as test cultures. The H 292 and HEp-2 cells yielded much higher inclusion counts for all the test strains than did HeLa 229 cells. When they were compared with each other, H 292 cells yielded more inclusions than did HEp-2 cells, and the differences were statistically significant in 10 of 18 test sets. A simple system with these two cell lines appeared to be very efficient for culturing C. pneumoniae. It does not require treatment of tissue cells with DEAE-dextran before infection, and it may eliminate the need for serial subpassages of specimens to increase culture sensitivity. Monolayers of these cells remained intact and viable in the Chlamydia growth medium so that reinfection could take place, resulting in greatly increased inclusion counts for specimens containing few infectious units. This system may make it more practical for laboratories to culture for C. pneumoniae for treatment of infections and outbreak intervention and will facilitate studies on this recently recognized pathogen.

Enhancement of misonidazole chemosensitization effect by mild local hyperthermia

In an attempt to increase the chemosensitization effect of the alkylating agents 1,3 bis(2-chloroethyl)-1-nitrosourea (BCNU) and cyclophosphamide (CY), by misonidazole (MISO) at the tumor site, mild hyperthermic treatment (41.5 degrees C, 1 hr) was applied at various administration sequences. C3Hf/Sed mice bearing subcutaneous FSa-II tumors in the foot were used for a tumor growth time assay. Local hyperthermic treatment increased the antitumor activities of BCNU and CY by 1.4 and 2.4 fold, respectively. MISO at 2.5 mmole/kg potentiated the antitumor activities of BCNU, but not CY, at normal body temperature. There were no significant improvement of MISO chemosensitization when heat was given before the administration of BCNU and CY. However, a significant enhancement of chemosensitization was observed when heat was given after the administration of MISO and the alkylating agents. Enhancement ratios of about 2.4 and 4.7 were observed with BCNU and CY, respectively. There may be two mechanisms responsible for this thermal enhancement. First, the MISO pre-incubation time that was required for the expression of chemosensitization effect decreased substantially at elevated temperatures. This hypothesis was supported by the pharmacokinetic studies that MISO was rapidly eliminated from tumors in the first 10 min during the local heat treatment and remained at a plateau with a concentration of about 5-fold less than the peak MISO concentration in the control tumors. This rapid elimination might result from the increase in the rate of hypoxic metabolism of MISO in heated tumors. Second, heat may increase the MISO-alkylating agent interactions, which are independent of pre-incubation time. This effect was especially pronounced in CY because pre-incubation-induced chemosensitization of CY in unheated tumor was insignificant in this study. The significant improvement of MISO chemosensitization at moderately elevated temperatures can be useful clinically in combined hyperthermia and chemotherapy treatment.

Radiosensitivity of mouse skin epithelial cell line established in serum-free culture: an alternative to animal use

A cultured line of murine skin epithelial cells was established to investigate the potential use of cultured cells as an alternative to animal use in radiation research. C3Hf/Sed newborn mouse skin cells have been successfully cultured in serum- and Ca(2+)-free medium with no terminal differentiation to keratinized cells. Presently, more than 25 passages have passed with no loss of stem cell capability. The radiosensitivity and repair of sublethal and potentially lethal radiation damages were investigated in this epithelial cell line. The population cell doubling time was 25 +/- 2.9 hr at 37 degrees C. The clonal growth of epithelial cells after irradiation was performed in the serum-free medium in the presence of lethally irradiated skin fibroblasts. Single dose survival curves of exponentially growing epithelial cells were investigated from the seventh to the twenty-third passages, and no significant changes in radiosensitivity and doubling time were found. The confluent epithelial cells also showed an identical sensitivity to radiation. The alpha/beta ratios of survival curves fitted by the linear quadratic model were 6.1 +/- 1.0 and 5.9 +/- 1.3 Gy for cells in exponential and confluent phases, respectively. The survival curve of epithelial cells left in confluence for 8 hr after irradiation showed a smaller beta value than that of cells plated immediately after irradiation with a resultant alpha/beta ratio of 9.5 +/- 3.8 Gy. This alpha/beta ratio was identical to those found in many animal experiments, suggesting a potential use of this cell line as an alternative to animal use. The magnitude of repair of sublethal damage following 6 Gy was greater than that following 3.9 Gy. Survival curves were also obtained following twice-a-day irradiations with no sign of rapid repopulation. These results are discussed by comparing with published in vivo and in vitro data.

Effect of administration schedules on the potentiation of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) by misonidazole in subcutaneous 9L tumors

Our previous studies demonstrated that metabolism of misonidazole (MISO) by hypoxic cells is required to potentiate the cytotoxicity of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) in sc 9L tumors. To determine the influence of administration schedules on this chemosensitization, tumors were either clamped to produce a reversible hypoxia or left unclamped. MISO (2.5 mmoles kg-1) was administered to rats with unclamped tumors simultaneously with BCNU (9 or 12 mg kg-1), 20 min before BCNU, or 2.5 hr before BCNU, and the drug pharmacokinetics and BCNU cytotoxicity were measured. MISO administered 20 min or 2.5 hr before BCNU increased the plasma elimination half-time (t1/2) of BCNU, but MISO administered simultaneously with BCNU did not change the plasma elimination t1/2 of BCNU. In unclamped sc 9L tumors, all administration schedules decreased the peak BCNU concentration and increased the initial BCNU elimination t1/2; however, the BCNU exposure dose (AUC0-infinity) calculated from these data did not change significantly. In agreement with the AUC calculations, none of the administration schedules altered the BCNU cytotoxicity in unclamped tumors. If the tumors were clamped for 5-120 min after the peak MISO concentration was reached, BCNU-induced cell kill was increased by a constant factor of 3 over the first hour of the clamping period and by an additional factor of 7 over the second hour of the clamping period. If the tumors were clamped for 2 hr after the peak MISO concentration was reached and then BCNU administered 0-60 min after the clamp was released, this chemosensitization remained at a constant factor of approximately 20 for the first 10 min, and then decreased rapidly to a factor of approximately 3 by 20 min after the clamp was released. These data indicate that in sc 9L tumors, (1) at least two biochemical mechanisms are involved in this MISO-BCNU interaction, one of which depends on the duration and extent of the metabolism of MISO by hypoxic cells, and (2) reoxygenation does not immediately eliminate the potentiation of BCNU by MISO. These data also suggest that MISO should be given 2-4 hr before BCNU to achieve the maximum chemosensitization in clinical trials.

2-Nitroimidazole potentiation of nitrosourea induced cytotoxicity in subcutaneous implants of rat 9L brain tumor cells

To determine if the 2-nitroimidazole (2-NI) and the nitrosourea (NU) in a brain tumor chemopotentiation trial should be selected on the basis of known structure-activity relationships (electron affinity, lipophilicity, alkylating activity, carbamoylating activity), s.c. implants of rat 9L brain tumor cells were treated with combinations of misonidazole (MISO) or etanidazole (SR-2508) administered under oxic and hypoxic conditions, and BCNU, CCNU or chlorozotocin (CLZ) administered under oxic conditions. Cell kill was assessed by an in vivo to in vitro colony formation assay. To mimic the 'preincubation effect', the 2-NI was injected i.p., and 30 min later the tumor was clamped. After 2 hr, the clamp was released, and the NU administered immediately. MISO (2.5 mmole/kg) and SR-2508 (3.75 mmole/kg) reached the same peak tumor concentration in 30 min. Both 2-NIs were metabolized at the same rate in the clamped tumors; however, metabolism of the 2-NIs by hypoxic cells over the 2 hr clamping period did not produce any measurable s.c. 9L cell kill. The relative effectiveness of the NUs for killing oxic s.c. 9L tumor cells was: BCNU greater than CCNU greater than CLZ. Clamping the tumor prior to NU administration did not change the NU cytotoxicity. No potentiation of the NU cytotoxicity by the 2-NIs was observed in oxic tumors. Although metabolism of MISO by hypoxic cells did not result in potentiation of CLZ cytotoxicity at any dose, it resulted in potentiation of BCNU cytotoxicity at all doses and CCNU cytotoxicity at high doses.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacokinetics and cytotoxicity of RSU-1069 in subcutaneous 9L tumours under oxic and hypoxic conditions

The acute toxicity, pharmacokinetics and hypoxic cytotoxicity of RSU-1069 were investigated using the subcutaneous (sc) rat 9L tumour model. The pharmacokinetics were studied after i.p. injection of RSU-1069 (20 mg kg-1 or 100 mg kg-1). For both doses, the elimination of RSU-1069 followed first-order kinetics in both plasma and unclamped tumours. After 100 mg kg-1, the peak plasma concentration of RSU-1069 was 40 micrograms ml-1; the elimination t1/2 was 39.3 +/- 11.1 min. After 20 mg kg-1, the peak plasma concentration was 3 micrograms ml-1; the elimination t1/2 was 47.8 +/- 6.3 min. In unclamped tumours, the peak concentration was 50 micrograms g-1 with an elimination t1/2 of 36.1 +/- 9.6 min for the 100 mg kg-1 dose, and 4 micrograms g-1 with an elimination t1/2 of 41.9 +/- 6.1 min for the 20 mg kg-1 dose. The tumour and plasma elimination half-times were not significantly different (P greater than 0.2) for the two doses. Clamping the tumour 30 min after administration of 100 mg kg-1 of RSU-1069 decreased the tumour elimination t1/2 to 10.9 +/- 1.4 min. After releasing the clamp, RSU-1069 returned rapidly to the unclamped tumour concentration. The unclamped tumour/plasma ratio reached a maximum of 4-6, then decreased to a constant value of about 2 for both doses, indicating that RSU-1069 accumulates in these 9L tumours. RSU-1069 kills hypoxic sc 9L cells more efficiently than oxic sc 9L cells; at a surviving fraction of 0.5, the SER was 4.8. For in vitro 9L cells, the SER was approximately 50 when the comparison was between those treated in 2.1% 0(2) and those treated in less than 7.5 x 10(-3)% 0(2); it was approximately 100 when the comparison was between those treated in 21% 0(2) and those treated in less than 7.5 x 10(-3)% 0(3). Tumours treated with RSU-1069 and clamped for various times exhibited biphasic cell-kill kinetics; at 50 mg kg-1, little additional cell kill was achieved after 40 min of clamping. Our data also indicate that RSU-1069 is 300-1000 fold more efficient than misonidazole or SR2508 for killing hypoxic sc 9L tumour cells in situ.

Chemosensitization of the nitrosoureas by 2-nitroimidazoles in the subcutaneous 9L tumor model: pharmacokinetic and structure-activity considerations

Alterations of the pharmacokinetics and cytotoxic effects of the nitrosoureas, 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) and 1-(2-chloroethyl)-3-(cyclohexyl)-1-nitrosourea (CCNU) by the 2-nitroimidazoles, misonidazole (MISO) and SR-2508 were investigated using the subcutaneous (sc) 9L tumor model in male Fisher 344 rats. When 50 mg/kg of CCNU was given i.p., the peak plasma concentration of CCNU was about 3 micrograms/ml. CCNU was eliminated with biphasic kinetics that had a terminal half-time (T1/2) of approximately 47 min. When 2.5 mmole/kg of MISO was given i.p. 150 min before CCNU, the peak plasma concentration of CCNU was increased by approximately 63% with no change in the elimination kinetics. Clamping did not change the pharmacokinetics of CCNU in either plasma or tumors. MISO pretreatment increased the peak CCNU concentration in unclamped tumors by 3-fold, but had no effect on the CCNU pharmacokinetics in clamped tumors. With the exception of a decrease in the peak BCNU concentration in tumors similar to that observed with MISO, SR-2508 (3.75 mmole/kg, i.p.) did not change the pharmacokinetics of BCNU or CCNU in plasma and tumors. CCNU had no effect on the MISO concentration in plasma and unclamped tumors. However, in the clamped tumors, CCNU delayed the return of the MISO concentration to the unclamped tumor level by about an additional 60 min after the clamp was released. SR-2508 was eliminated from the plasma with biphasic kinetics having an initial and terminal T1/2 of approximately 11 and approximately 76 min, respectively. SR-2508 reached a peak tumor concentration of about 500 micrograms/ml in 30 min. The elimination T1/2 for SR-2508 in unclamped and clamped tumors was approximately 81 and approximately 42 min, respectively. When the clamp was released, the SR-2508 concentration returned to the level found in the unclamped tumors approximately 90 min after it reached its nadir; BCNU and CCNU had no effect on the kinetics of this process. MISO significantly potentiated the cytotoxicity of BCNU in clamped tumors at surviving fractions less than or equal to 0.5. MISO did not potentiate the cytotoxicity of CCNU until the surviving fraction reached 0.05. SR-2508 did not potentiate the cytotoxicity of either BCNU or CCNU.(ABSTRACT TRUNCATED AT 400 WORDS)

Simple, efficient purification of filamentous hemagglutinin and pertussis toxin from Bordetella pertussis by hydrophobic and affinity interaction

Two major antigens of Bordetella pertussis, filamentous hemagglutinin (FHA) and pertussis toxin (PT), were efficiently purified from culture filtrate by exploiting their relative hydrophobicities and differences in affinity to sialic acid-containing protein. High yields of FHA (40 to 80 mg/liter) and PT (8 to 16 mg/liter) were first produced by growing the bacteria in the modified CL medium. The FHA and PT in the culture filtrate were adsorbed onto butyl-Sepharose by hydrophobic interaction at appropriately high ionic strength. Elution of the antigens was effected by decreasing their hydrophobicities with a buffer of low ionic strength. FHA was then separated from PT with an affinity column of fetuin-Sepharose. The fraction passing through the column contained purified FHA, and the fetuin-bound PT was eluted with buffered MgCl2. The FHA and PT purified by these steps were electrophoretically and serologically identical to the reference purified FHA and PT preparations. Approximately 16 to 32 mg of purified FHA and 4 to 8 mg of purified PT were obtained from 1 liter of culture filtrate. The described procedure for making FHA and PT antigens from B. pertussis for serologic and immunologic use is very simple, efficient, and reproducible.

Purification and characterization of subunits of a high molecular weight human salivary mucin

A high molecular-weight mucin was purified from human submandibular-sublingual saliva. The purity of the mucin preparation was demonstrated by the absence of other salivary proteins, by antibody reactivity and by gel electrophoresis. After reduction with mercaptoethanol a putative link component with approximate Mr 150,000 and a glycoprotein component of higher Mr could be detected by gel electrophoresis. These subunits were subsequently purified and they showed distinct differences in their amino acid compositions, demonstrating that the mucin consisted of two different subunits. The link had a number of similarities with the link component of intestinal mucin and a parotid agglutinin and has previously been shown to cross-react with antiserum to link component from intestinal mucin. Salivary and intestinal mucins may therefore have similar subunit structure.

Preparation of filamentous hemagglutinin from Bordetella pertussis and assay for serum antibodies to filamentous hemagglutinin and pertussis toxin for clinical and public health laboratories

A procedure that is sufficiently simple and economical for use in clinical and public health laboratories for producing and purifying filamentous hemagglutinin (FHA) and determining antibodies to this major antigen of Bordetella pertussis in serum is described. High yields of FHA (40 to 80 mg/liter) were obtained in the supernatant by cultivating B. pertussis in modified CL medium. The FHA antigen was separated from pertussis toxin (PT) and other antigens by chromatography on hydroxylapatite. Removal of residual PT activity in the FHA fraction was effected by affinity absorption of PT with Fetuin immobilized to Sepharose 4B. The FHA was used as the antigen for determining titers of immunoglobulin G (IgG), IgA, and IgM to FHA in sera of patients with pertussis by an improved enzyme-linked immunosorbent assay. Development of the interfering background color commonly observed in conventional FHA enzyme-linked immunosorbent assay procedures was eliminated by washing the reaction wells with a buffer of high ionic strength before adding the peroxidase conjugates. In the absence of nonspecific background color, the reaction endpoints were easy to read. The FHA prepared by the procedure described was identical to a reference preparation of purified FHA in sodium dodecyl sulfate-polyacrylamide gel electrophoresis profiles and serological specificity assays. High yields of FHA were obtained from all four strains of B. pertussis tested in this study, indicating that the procedure for enhanced production of FHA may be generally applicable to other strains of B. pertussis. Results from tests of 50 serum specimens with clinical information on pertussis for FHA and PT antibodies by the assay procedures described exemplified the usefulness and caveats of serodiagnosis for pertussis.

Ability of the alpha and beta anomers of chlorozotocin to kill rat 9L tumor cells in vitro

Chlorozotocin (CLZ), a nitrosourea synthesized in the hope that it would have little bone marrow toxicity, has been shown to be effective against animal tumors and tumor cells in culture. However, the clinical results with CLZ have been disappointing. The original report on the synthesis of CLZ indicated that alpha and beta anomers at the D-glucose moiety should be expected, particularly when CLZ is placed in aqueous solution. In this study, the alpha and beta anomers have been separated by high-performance liquid chromatography and characterized by UV spectroscopy, mass spectroscopy, and nuclear magnetic resonance. The equilibration and decomposition of the anomers in various physiological solutions were determined as a function of temperature, pH, and serum concentration. In Eagle's basal medium (pH 7.2) held at 25 degrees C, CLZ decomposed with a t1/2 of approximately 82 min; at 37 degrees C with serum, CLZ decomposed with a t1/2 of less than 10 min. In these two cases, the beta:alpha ratio reached 1 in approximately 48 min and less than 5 min, respectively. The maximum beta:alpha ratio obtained in all cases ranged from 1.25 to 1.5. After holding CLZ in tissue culture medium and compensating for its decomposition, 9L rat brain tumor cells were treated in vitro with CLZ having different ratios of the alpha and beta anomers. These experiments demonstrated that the beta anomer has little, if any, ability to kill 9L cells. Thus, this anomerization phenomenon may have been responsible for the disappointing clinical results with CLZ. Our data suggest that appropriate preparation, handling, and drug delivery procedures might be devised to minimize this problem in both experimental and clinical situations.

Biodistribution of misonidazole and 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) in rats bearing unclamped and clamped 9L subcutaneous tumors

The biodistribution of misonidazole (MISO) and 1,3bis(2-chloroethyl)-1-nitrosourea (BCNU) was studied using the subcutaneous (s.c.) 9L tumor model in male Fisher 344 rats. A transient hypoxia in these tumors was created by clamping the blood supply to the tumor. Reoxygenation occurred upon release of the clamp. The plasma and tumor concentrations of MISO and BCNU were quantitated by high pressure liquid chromatography. When 12 mg/kg of BCNU was given i.p. without MISO, the peak plasma concentration was about 6 micrograms/ml, and the elimination half-time was about 16 min. When 2.5 mmole/kg of MISO was given i.p. 150 min before the BCNU, the peak plasma concentration of BCNU increased by approximately 33%, and the plasma elimination half-time increased by approximately 57%. Clamping the tumor for 120 min did not significantly change the BCNU concentration in plasma, but in tumors the time to reach the peak level was delayed slightly, and the peak concentration was reduced when compared to that in the unclamped tumors. MISO pretreatment decreased the BCNU peak concentration in both unclamped and clamped tumors, but the decrease was more pronounced in the unclamped tumors. In both unclamped and clamped tumors, the BCNU concentration and its rate of disappearance were identical about 30 min after BCNU administration, with or without MISO pretreatment. The elimination half-time of MISO from the plasma (approximately 142 min) was identical for rats with unclamped or clamped tumors. The half-time for the disappearance of MISO from unclamped tumors was about 98 min. BCNU had no effect on the MISO concentration in plasma and unclamped tumors. MISO disappeared in the clamped tumors with a half-time of about 40 min. When the clamp was released, the MISO concentration returned to the level in the unclamped tumors after about 45 min. BCNU delayed the return of the MISO concentration to the unclamped tumor level by about 60 min. Two conclusions can be drawn from this study. First, the pharmacokinetics of each drug changed when the two drugs were combined. Second, the data indicate that alterations in the tumor BCNU pharmacokinetics are not the major mechanism responsible for the chemopotentiation previously measured in s.c. 9L tumors.

New, practical approach to detecting antibody to pertussis toxin for public health and clinical laboratories

A new, practical method for determining antibody to pertussis toxin (PT) by enzyme-linked immunosorbent assay for public health and clinical laboratories is possible because of recent advances in understanding the pathobiology of Bordetella pertussis and the physicochemical properties of PT. The new approach does not require the use of highly purified PT antigen, which is difficult and expensive for most laboratories to obtain. Moreover, it employs only reagents that are commercially readily available. The method combines the purification of PT antigen and an assay for PT antibody into one process. It depends on (i) growth of B. pertussis in a simple, defined medium to obtain a PT-rich supernatant with little contamination of cellular antigens; (ii) a simple, one-step concentration of PT in the culture supernatant with Affi-Gel Blue (Bio-Rad Laboratories, Richmond, Calif.); and (iii) specific adsorption of PT as the test antigen to microtiter wells coated with fetuin for the enzyme-linked immunosorbent assay. The procedure is sensitive and specific for PT antibody. It is technically simple, reproducible, and can be performed in a modestly equipped laboratory.

Role of nonprotein thiols in enzymatic reduction of 2-nitroimidazoles

The role of nonprotein thiols (NPSH) in the enzymatic reduction of the nitro function in 2-nitroimidazoles (2-NI) has been investigated. The addition of NPSH has been shown previously to protect cells from the hypoxic cytotoxicity of 2-NI, whereas depletion of NPSH enhances the hypoxic cytotoxicity. In this report, we have investigated the effects of thiol depleting agents, N-ethylmaleimide (NEM) and diethyl maleate (DEM), on the enzymatic reduction of the nitro group. Cytosolic and microsomal fractions of rat hepatic tissue and xanthine oxidase were employed as sources of nitro reductases. Addition of NPSH caused an enhancement in the reduction of the nitro group of 2-NI; cysteine was significantly more effective than glutathione (GSH) in stimulating the enzymatic reduction. The reduction of the nitro function was decreased markedly in the presence of NEM or DEM. Addition of cysteine or GSH reversed the inhibition with NEM. Both NEM and DEM also attenuated the enhancement of reduction observed after the addition of NPSH. These results suggest that the addition of NPSH facilities the reduction of the nitro function to the reduced intermediates that may be inactivated by an excess of NPSH, whereas the depletion of NPSH allows the accumulation of the toxic nitro radicals causing increased cytotoxicity.