Role for Bcl-xL as an inhibitor of cytosolic cytochrome C accumulation in DNA damage-induced apoptosis

Cytochrome C is a mitochondrial protein that induces apoptosis when released into the cytosol or when added to cell-free extracts. Here we show that cells that overexpress the Bcl-2-related protein Bcl-xL fail to accumulate cytosolic cytochrome C or undergo apoptosis in response to genotoxic stress. Coimmunoprecipitation studies demonstrate that Bcl-xL associates with cytochrome C. Cytochrome C binds directly and specifically to Bcl-xL and not to the proapoptotic Bcl-xs protein. The results also demonstrate that Bcl-xs blocks binding of cytochrome C to Bcl-xL. Our findings support a role for Bcl-xL in protecting cells from apoptosis by inhibiting the availability of cytochrome C in the cytosol.

Augmented sympathetic tone alters muscle metabolism with exercise: lack of evidence for functional sympatholysis

It is unclear whether sympathetic tone opposes dilator influences in exercising skeletal muscle. We examined high levels of sympathetic tone, evoked by lower body negative pressure (LBNP, -60 mmHg) on intramuscular pH and phosphocreatine (PCr) levels (31P-nuclear magnetic resonance spectroscopy) during graded rhythmic handgrip (30 contractions/min; approximately 17, 34, 52 and 69% maximal voluntary contraction). Exercise was performed with LBNP and without LBNP (Control). At the end of exercise, LBNP caused lower levels of muscle pH (6.59 +/- 0.09) compared with Control (6.78 +/- 0.05; P < 0.05). PCr recovery, an index of mitochondrial respiration, was less during the recovery phase of the LBNP trial. Exercise mean arterial pressure was not altered by LBNP. The protocols were repeated with measurements of forearm blood flow velocity and deep venous samples (active forearm) of hemoglobin (Hb) saturation, pH, and lactate. With LBNP, mean blood velocity was reduced at rest, during exercise, and during recovery compared with Control (P < 0.05). Also, venous Hb saturation and pH levels during exercise and recovery were lower with LBNP and lactate was higher compared with Control (P < 0.05). We conclude that LBNP enhanced sympathetic tone and reduced oxygen transport. At high workloads, there was a greater reliance on nonoxidative metabolism. In other words, sympatholysis did not occur.

Functional interaction between DNA-PK and c-Abl in response to DNA damage

How DNA damage is converted into intracellular signals that can control cell behaviour is unknown. The c-Abl protein tyrosine kinase is activated by ionizing radiation and certain other DNA-damaging agents, whereas the DNA-dependent protein kinase (DNA-PK), consisting of a serine/threonine kinase and Ku DNA-binding subunits, requires DNA double-strand breaks or other DNA lesions for activation. Here we demonstrate that c-Abl interacts constitutively with DNA-PK. Ionizing radiation stimulates binding of c-Abl to DNA-PK and induces an association of c-Abl with Ku antigen. We show that DNA-PK phosphorylates and activates c-Abl in vitro. Cells deficient in DNA-PK are defective in c-Abl activation induced by ionizing radiation. In a potential feedback mechanism, c-Abl phosphorylates DNA-PK, but not Ku, in vitro. Phosphorylation of DNA-PK by c-Abl inhibits the ability of DNA-PK to form a complex with DNA. We also show that treatment of cells with ionizing radiation results in phosphorylation of DNA-PK that is dependent on c-Abl. Our results support the hypothesis that there are functional interactions between c-Abl and DNA-PK in the response to DNA damage.

An Open Trial of Trimethoprim Alone against Cyclospora Infections

Cyclospora is a coccidian parasite that infects the upper intestine and causes a prolonged illness consisting of fatigue, anorexia, and diarrhea. Untreated infections can last for several weeks.1 Trimethoprim-sulfamethoxazole (co-trimoxazole) was found to be an effective treatment for Cyclospora infections in a 1994 study performed in Nepal.2 However, people with known allergies to sulfa drugs cannot take co-trimoxazole. A number of antibiotics have been tried against Cyclospora infections without success, including norfloxacin, tinidazole, diloxanide furoate, and quinacrine hydrochloride. Azithromycin was not successful in a small open trial in 1993.3 Trimethoprim is not chemically related to sulfa, and allergy to co-trimoxazole is usually attributed to the sulfamethoxazole component. In order to find a treatment for people infected with Cyclospora who are allergic to sulfa drugs, we undertook an open trial of trimethoprim alone, in a dose of 200 mg twice a day for 7 days.

Proteolytic activation of protein kinase C delta by an ICE/CED 3-like protease induces characteristics of apoptosis

Recent studies have shown that protein kinase C (PKC) delta is proteolytically activated at the onset of apoptosis induced by DNA-damaging agents, tumor necrosis factor, and anti-Fas antibody. However, the relationship of PKC delta cleavage to induction of apoptosis is unknown. The present studies demonstrate that full-length PKC delta is cleaved at DMQD330N to a catalytically active fragment by the cysteine protease CPP32. The results also demonstrate that overexpression of the catalytic kinase fragment in cells is associated with chromatin condensation, nuclear fragmentation, induction of sub-G1 phase DNA and lethality. By contrast, overexpression of full-length PKC delta or a kinase inactive PKC delta fragment had no detectable effect. The findings suggest that proteolytic activation of PKC delta by a CPP32-like protease contributes to phenotypic changes associated with apoptosis.

Activation of p38 mitogen-activated protein kinase by c-Abl-dependent and -independent mechanisms

The p38 mitogen-activated protein (MAP) kinase defines a subgroup of the mammalian MAP kinases that are induced in response to lipopolysaccharide, hyperosmolarity, and interleukin 1. p38 MAP kinase appears to play a role in regulating inflammatory responses, including cytokine secretion and apoptosis. Here we show that diverse classes of DNA-damaging agents such as cisplatinum, 1-beta-D-arabinofuranosylcytosine, UV light, ionizing radiation, and methyl methanesulfonate activate p38 MAP kinase. We also demonstrate that cells deficient in c-Abl fail to activate p38 MAP kinase after treatment with cisplatinum and 1-beta-D-arabinofuranosylcytosine but not after exposure to UV and methyl methanesulfonate. Reconstitution of c-Abl in the Abl-/- cells restores that response. Similar results were obtained for induction of the Jun-NH2-kinase/stress-activated protein kinase. These findings indicate that p38 MAP and Jun-NH2-kinase/stress-activated protein kinases are differentially regulated in response to different classes of DNA-damaging agents.

The stress response to ionizing radiation involoves c-Abl-dependent phosphorylation of SHPTP1

c-Abl is a nonreceptor tyrosine kinase that is activated by certain DNA-damaging agents. The present studies demonstrate that nuclear c-Abl binds constitutively to the protein tyrosine phosphatase SHPTP1. Treatment with ionizing radiation is associated with c-Abl-dependent tyrosine phosphorylation of SHPTP1. The results demonstrate that the SH3 domain of c-Abl interacts with a WPDHGVPSEP motif (residues 417-426) in the catalytic domain of SHPTP1 and that c-Abl phosphorylates C terminal Y536 and Y564 sites. The functional significance of the c-Abl-SHPTP1 interaction is supported by the demonstration that, like c-Abl, SHPTP1 regulates the induction of Jun kinase activity following DNA damage. These findings indicate that SHPTP1 is involved in the response to genotoxic stress through a c-Abl-dependent mechanism.

c-Abl activation regulates induction of the SEK1/stress-activated protein kinase pathway in the cellular response to 1-beta-D-arabinofuranosylcytosine

Previous work has shown that treatment of cells with the antimetabolite 1-beta-D-arabinofuranosylcytosine (ara-C) is associated with induction of the c-jun gene. The present studies demonstrate that ara-C activates the c-Abl non-receptor tyrosine kinase. We also demonstrate that activity of the stress-activated protein kinase (SAP kinase/JNK) is increased in ara-C-treated cells. Using cells deficient in c-Abl (Abl-/-) and after introduction of the c-abl gene, we show that ara-C-induced c-Abl activity is necessary for the stimulation of SAP kinase. Other studies using cells transfected with a SEK1 dominant negative demonstrate that ara-C-induced SAP kinase activity is SEK1-dependent. Furthermore, we show that overexpression of truncated c-Abl results in activation of the SEK1/SAP kinase cascade.

Seminal vesicle abscess: a case report and review of literature

Seminal vesicle abscess, a rare urologic entity, is usually diagnosed with computerized tomography (CT) scan. We report a case of seminal vesicle abscess that required a transrectal ultrasonography to confirm the diagnosis. An analysis of 20 cases of seminal vesicle abscess reported in the literature is also reviewed.

Ultrasound guided seminal vesicle biopsies in men with suspected prostate cancer

PURPOSE

The histology of ultrasound guided seminal vesicle biopsies is assessed and the results are correlated with clinical or pathological stage of prostate cancer.

MATERIALS AND METHODS

A total of 517 consecutive men underwent bilateral (515) or unilateral (2) seminal vesicle biopsy during sextant biopsy of the prostate.

RESULTS

Seminal vesicle epithelium and muscularis were identified in 490 of 1,032 biopsy specimens (47%) and smooth muscle consistent with seminal vesicle muscularis was identified in 393 (38%). The seminal vesicle biopsy was positive for cancer in 7 of 123 patients (6%) with with clinical stages T1c and T2 tumors, 27 of 60 (45%) with stages T3 to 4 disease and 9 of 13 (69%) with metastatic cancer. Of 39 patients who underwent radical prostatectomy 1 of 36 (3%) without and 0 of 3 (0%) with seminal vesicle invasion had a positive seminal vesicle biopsy.

CONCLUSIONS

Seminal vesicle epithelium and muscularis or smooth muscle consistent with the seminal vesicle muscularis can be procured in most patients using contemporary ultrasound guided biopsy techniques. However, apparently false-negative seminal vesicle biopsies are not uncommon and seminal vesicle biopsies contribute little to the staging of T1c and T2 tumors.

Association of the DF3/MUC1 breast cancer antigen with Grb2 and the Sos/Ras exchange protein

The DF3/MUC1 mucin-like glycoprotein is aberrantly overexpressed in human breast carcinomas. Although the precise functional role of this protein remains unclear, the cytoplasmic tail contains potential tyrosine phosphorylation sites for binding to Src homology 2 (SH2) domains. In the present studies using human MCF-7 breast cancer cells, we show that tyrosine phosphorylated DF3 directly interacts with the SH2 domain of the adaptor protein Grb2. The findings indicate that a pYTNP site in DF3 is responsible for this interaction. The results also demonstrate that the DF3/Grb2 complex associates with the guanine nucleotide exchange protein Sos. Because Sos binds to the SH3 domains of Grb2 and, thereby, associates with Ras at the cell membrane, formation of a DF3/Grb2/Sos complex supports a role for DF3 in intracellular signaling.

Activation of the c-Abl tyrosine kinase in the stress response to DNA-damaging agents

The product of the c-abl gene is a non-receptor tyrosine kinase that is localized to the nucleus and cytoplasm. The precise function of c-Abl is unknown. Here we show that ionizing radiation activates c-Abl. Similar results were obtained with the alkylating agents cis-platinum and mitomycin C. We also demonstrate that cells deficient in c-Abl fail to activate Jun kinase (JNK/SAP kinase) after ionizing radiation or alkylating agent exposure and that reconstitution of c-Abl in these cells restores that response. In contrast, the stress response to tumour-necrosis factor is stimulated by a c-Abl-independent mechanism. These findings indicate that c-abl is involved in the stress response to DNA-damaging agents.

Prostate specific antigen after gonadal androgen withdrawal and deferred flutamide treatment

PURPOSE

We assess the impact of deferred flutamide treatment on the serum prostate specific antigen (PSA) level in patients with localized or metastatic cancer.

MATERIALS AND METHODS

The study included 45 patients with localized cancer and 50 with metastatic cancer with an increasing (87) or stable (8) PSA level after gonadal androgen withdrawal.

RESULTS

Of 40 evaluable patients with localized cancer and 50 with metastatic cancer 32 (80%) and 27 (54%), respectively, had a PSA decrease of 50% or more of baseline during flutamide treatment (p = 0.014). Among patients with localized cancer actuarial analysis of freedom from PSA elevation during flutamide treatment favored those with a 50% or greater PSA decrease (p = 0.006) but in patients with metastatic cancer the analysis revealed no significant difference.

CONCLUSIONS

The relative density of tumor cells that are dependent on adrenal androgen after gonadal androgen withdrawal may be greater in patients with localized cancer and deferred flutamide treatment may enhance cancer control in those with localized disease.

Prostate specific antigen regression and progression after androgen deprivation for localized and metastatic prostate cancer

To identify prostate specific antigen (PSA) functions of prognostic significance in regard to treatment with androgen deprivation for prostate cancer we analyzed the pretreatment PSA, PSA half-life, PSA nadirs, times to PSA elevation and PSA doubling times in 245 patients with localized and 78 with metastatic disease who were treated with this modality. There was a direct correlation between the pretreatment PSA and the time to PSA elevation in patients with localized cancer (p = 0.000003) but no significant correlation in those with metastatic cancer. The PSA half-life was highly variable and did not correlate with other PSA functions of prognostic significance. Incremental increases in the PSA nadir correlated with the time to PSA elevation in patients with localized and metastatic cancer (p < 0.000001 and p = 0.00009, respectively), and with other parameters of prognostic significance. The median PSA doubling time in 26 patients with localized cancer in whom distant metastases did not develop (7.5 months) was significantly longer than that in 7 in whom new metastases developed (2.5 months) and in 43 with preexisting metastatic cancer (2.5 months) (p < 0.05 and p < 0.0001, respectively). In the 7 patients with localized cancer in whom metastases developed the median of the ratios of the PSA when the metastases were manifest and the pretreatment PSA was 0.14, and in 24 patients with preexisting metastatic cancer the median of the ratios of the antemortem PSA and the pretreatment PSA was 1.2. These data show that PSA synthesis by prostate cancer is reduced after androgen deprivation but that the PSA nadir and PSA doubling time following treatment provide important prognostic information.

Synthesis and in vivo hypoglycemic screening studies on some life essential metal complexes of oral antidiabetic [N-(p-tolylsulphonyl)-N'-n butyl-urea] (tolbutamide)

Present communication deals with the synthesis of complexes of [N-(p-tolylsulphonyl)-N'-n butyl-urea], with certain transition metals viz. Cu(II), Zn(II), Fe(II) and Cd(II). Structures of all the complexes have been established on the basis of their consistent elemental and spectral analysis. Also, it reports their in vivo hypoglycemic screening on albino rats. Out of all the complexes studied, Zn-Tolbutamide complex could be recommended as more potent hypoglycemic agent in lieu of tolbutamide alone.

Placebo-controlled trial of co-trimoxazole for Cyclospora infections among travellers and foreign residents in Nepal

Cyclospora is a coccidian (previously referred to as cyanobacterium-like bodies) that has been implicated in cases of prolonged diarrhoea. The average duration of symptoms is more than three weeks, and no specific treatment has been shown to shorten the illness. A case report suggested that co-trimoxazole may be effective. Expatriate persons with gastrointestinal complaints and cyclospora detected on examination of faeces were recruited from two clinics in Kathmandu, Nepal, between May and August, 1994. Participants were assigned in a randomised, double-blinded manner to receive either cotrimoxazole (160 mg trimethoprim, 800 mg sulphamethoxazole) or placebo tablets twice daily for 7 days. Of 40 patients included in the study, 21 received cotrimoxazole and 19 placebo. There were no significant differences between these two groups in age, sex, time in Nepal, duration or severity of illness, or presence of other enteric pathogens. After 3 days, 71% of patients receiving co-trimoxazole still had cyclospora detected, compared with 100% of patients receiving placebo (p = 0.016). After 7 days, cyclospora was detected in 1 (6%) of 16 patients treated with co-trimoxazole who submitted stool specimens compared with 15 (88%) of 17 patients receiving placebo (p < 0.0001). Eradication of the organism was correlated with clinical improvement. There was no evidence of relapse of infection among treated patients followed for an additional 7 days. Treatment with co-trimoxazole for 7 days was effective in curing cyclospora infection among an expatriate population in Nepal.

Variable histology of anastomotic biopsies with detectable prostate specific antigen after radical prostatectomy

Progressive elevation of the prostate specific antigen (PSA) level after radical prostatectomy for adenocarcinoma is generally considered as irrefutable evidence of recurrent tumor. We assessed the results of 62 biopsies of the vesicourethral anastomosis in 41 men who had 3 or more consecutive PSA levels of 0.4 ng./ml. or greater after radical prostatectomy and no evidence of metastatic disease. The median PSA at the time of the first biopsy was 2.2 ng./ml. (range 0.4 to 50). Histological confirmation of recurrent cancer was established after 1 biopsy procedure in 39% of the patients and after 1 or more biopsy procedures in 59%. Biopsy was positive in 78% of 23 patients with an abnormal digital rectal examination, 40% of 5 with an abnormal transrectal ultrasound only, and 23% of 13 with a normal digital rectal examination and ultrasound. Among the patients with and without biopsy proved tumor recurrence there were no significant differences between the pathological stage or histological grade of the primary tumors, the month after surgery of the first detectable PSA level, the PSA doubling time, the month after surgery of the positive biopsy or the last negative biopsy, and the PSA level at the time of the positive biopsy or the last negative biopsy. In 6 cases benign prostatic tissue only was recovered from 1 or more biopsy specimens. This experience demonstrates that in patients with a detectable PSA after radical prostatectomy recurrent cancer may be difficult to document by biopsy of the vesicourethral anastomosis.

Genotoxicity of polychlorinated biphenyls (PCBs): recombinogenesis by biotransformation products

A coplanar polychlorinated biphenyl (PCB) when eaten by test animals increased the rate of recombination in somatic cells, indicating a new mechanism of action for these compounds. Using the eye-mosaic test a high bioactivation strain of Drosophila that consumed 4,4'-dichlorobiphenyl (4,4'-DCB) manifested a genotoxicity rate that was three-fold greater than that in animals fed the solvent-spiked medium. This compound was not genotoxic in a suppressed bioactivation strain indicating that genotoxicity requires bioactivation of the compound. High bioactivation test strains made heterozygous for a paracentric inversion, a chromosomal rearrangement that suppresses homologous recombination, exhibited significantly reduced genotoxicity after treatment.

Experience with radical prostatectomy and radiation therapy for localized prostate cancer at a Veterans Affairs Medical Center

We assessed the actuarial survival of 357 patients with localized prostate cancer who were treated with radical prostatectomy or radiation therapy at a Veterans Affairs Medical Center between 1980 and 1991 and who were followed for a median of 59 months. During this period patients with clinical stages A2 and B tumors who had an anticipated life expectancy of 10 years or greater were generally treated with surgery. Patients with stages A2 and B tumors who were not candidates for surgery and those with stage C tumors were generally treated with radiation therapy. There were no significant differences among the cause specific, clinical disease-free and prostate specific antigen disease-free survival curves of patients with stages A2 and B tumors who were treated with radical prostatectomy (138) or radiation therapy (138) but the all cause and metastases-free survival curves favored the surgery group (p < 0.000001 and 0.046, respectively). There was no significant difference between the all cause survival curves of the patients with stages A2 and B tumors and of 81 patients with stage C tumors who were treated with radiation therapy. However, the cause specific survival curves favored the patients with stages A2 and B tumors (p = 0.000007). This study demonstrates that there is a high risk of death from co-morbidities in a hospital based population of American veterans with localized prostate cancer who are not candidates for radical prostatectomy.

Prostate specific antigen progression rates after radical prostatectomy or radiation therapy for localized prostate cancer

BACKGROUND

The purpose of the study was to determine whether a difference is noted in the rate of prostate specific antigen (PSA) elevation after radical prostatectomy or radiation therapy for localized prostate cancer.

METHODS

PSA doubling times were calculated by linear regression analysis in 50 patients who had been treated by radical prostatectomy and who had three or more increasing PSA levels and in 55 patients who had been treated with radiation therapy and who had three or more increasing PSA levels.

RESULTS

No significant difference was noted in the mean PSA doubling times in the two patient groups when stratified by the site of tumor recurrence or by pretreatment tumor stage, tumor grade, or acid phosphatase level.

CONCLUSIONS

Because the PSA doubling time probably parallels the tumor growth rate, these data suggest that the malignant potentials of recurrent tumor after radical prostatectomy and after radiation therapy are equivalent.

Results of partial patellectomy

We present an assessment of 200 patellar fractures treated mostly (175) by partial patellectomy. In 23 cases in which the quadriceps mechanism was 75% intact (MRC power approximately 4), the fractures were treated conservatively, with an overall acceptable result. The operative series with an average follow-up of 3 years has shown 80.3% excellent to good results. A classification of fractures of the patella, based on the anatomical fracture line and quadriceps functional loss as recorded in 690 case histories, is suggested.