Oxidative stress during antituberculous therapy in young and elderly patients

Using allantoin (ATN) as a marker for reactive oxygen species (ROS), oxidative stress during antituberculous (anti-TB) therapy was compared in 10 young and 9 elderly patients. Before treatment, ATN plasma concentrations in patients were similar to that of volunteers. Administration of a combination of isoniazid (INH), rifampicin (RIF) and pyrazinamide (PZA) increased plasma ATN in both groups of patients. ATN concentrations (M +/- SE) at six hours were higher (P < 0.05) in elderly than in young patients on day one, 8.22 +/- 1.50 vs 1.89 +/- 0.98 microgram/mL); day 30, (5.85 +/- 0.82 vs 0.87 +/- 0.57 microgram/mL; and day 90, (4.84 +/- 1.24 vs 0.52 +/- 0.50 microgram/mL). Because total amount of ATN excreted was similar in both groups on the three occasions, more ATN was formed in elderly than young patients. In conclusion, there was more oxidative stress in elderly than young patients. It is thereby suggested that Anti-TB drugs induce formation of ROS and elderly patients are at a greater risk of toxicity probably because of poor antioxidant mechanisms.

Genetic mosaicism at the insulin locus in liver associated with childhood hepatoblastoma

Hepatoblastoma is commonly associated with loss of heterozygosity (LOH) involving chromosome region 11p15.5. This region may contain an as yet unidentified tumor suppressor gene relevant to this and other tumors associated with the Beckwith-Wiedemann syndrome. Using the insulin (INS) locus as a marker for this region we have identified two of three patients with hepatoblastoma whose livers demonstrated genetic mosaicism. One tumor arose from the clone demonstrating LOH in the liver while the other arose from the clone without LOH.

Tuberculosis in health care workers at a hospital with an outbreak of multidrug-resistant Mycobacterium tuberculosis

OBJECTIVE

Investigate reports of tuberculosis in health care workers employed at a hospital with an outbreak of multidrug-resistant Mycobacterium tuberculosis.

DESIGN

Case series of tuberculosis in health care workers, January 1, 1989, through May 31, 1992. Antimicrobial susceptibility testing and restriction fragment length polymorphism analysis of M tuberculosis isolates. Longitudinal analysis of cumulative tuberculin skin test surveillance data. Assessment of infection control. The patients consisted of 361 health care workers who had either serial tuberculin skin tests or tuberculosis.

RESULTS

Six health care workers, the largest number linked to one multidrug-resistant tuberculosis outbreak, had disease due to M tuberculosis that matched the outbreak strain from hospitalized patients. The two who were seropositive for human immunodeficiency virus died, one of tuberculous meningitis and the other of multiple causes including tuberculosis. The estimated risk of a skin test conversion was positively associated with time and increased by a factor of 8.3 (1979 to 1992). In 1992 the annual risk for workers in the lowest exposure occupational group was 2.4%. In comparison, nurses and housekeepers had relative risks of 8.0 (95% confidence interval, 3.2 to 20.3) and 9.4 (95% confidence interval, 2.7 to 32.3), respectively. Laboratory workers had a relative risk of 4.2 (95% confidence interval, 1.1 to 15.5). Tuberculosis admissions increased, but the hospital had inadequate ventilation to isolate tuberculosis patients effectively. There were lapses in infection control practices.

CONCLUSIONS

Health care workers who were exposed during a hospital outbreak of multidrug-resistant tuberculosis had occupationally acquired active disease. The human immunodeficiency virus-infected health care workers with tuberculosis had severe disease and died. The risk of skin test conversion increased during the study period, and higher exposure occupations had elevated risk. Effective infection control is essential to prevent the transmission of tuberculosis to health care workers.

Screening for diabetes mellitus in adults. The utility of random capillary blood glucose measurements

OBJECTIVE

Because half of the people with non-insulin-dependent diabetes mellitus (NIDDM) are undiagnosed and because near-normal glycemic control can prevent diabetic complications, we evaluated the use of field-based random capillary blood glucose measurement as a screening test for NIDDM.

RESEARCH DESIGN AND METHODS

A cross-sectional sample of 828 Egyptians > or = 20 years of age underwent both a random capillary blood glucose measurement performed with a portable reflectance meter in the field and an oral glucose tolerance test in the laboratory. The sensitivity and specificity of random capillary blood glucose measurements in predicting the presence of NIDDM were evaluated.

RESULTS

Multivariate analyses showed that the screening test performed better when subjects had eaten shortly before the test (area under receiver operating characteristic curve, 0.87 for a 1-h postprandial period compared with 0.69 for an 8-h postprandial period) and that the optimal capillary blood glucose cutoff points to define a positive test increased with age. For a postprandial period of 1 h, cutoff points of 115 mg/dl for individuals 30 years of age and 140 mg/dl for those 75 years of age yielded similar performance characteristics (sensitivity 82% and specificity 78% for those 30 years old; sensitivity 81% and specificity 80% for those 75 years old).

CONCLUSIONS

Adjusting random capillary blood glucose measurements for the postprandial period and using age-specific cutoff point values can improve performance of the screening test.

A new and simple questionnaire to identify people at increased risk for undiagnosed diabetes

OBJECTIVE

To develop a simple questionnaire to prospectively identify individuals at increased risk for undiagnosed diabetes.

RESEARCH DESIGN AND METHODS

People with newly diagnosed diabetes (n = 164) identified in the Second National Health and Nutrition Examination Survey and those with neither newly diagnosed diabetes nor a history of physician-diagnosed diabetes (n = 3,220) were studied. Major historical risk factors for undiagnosed non-insulin-dependent diabetes were defined, and classification trees were developed to identify people at higher risk for previously undiagnosed diabetes. The sensitivity, specificity, and predictive value of the classification trees were described and compared with those of an existing questionnaire.

RESULTS

The selected classification tree incorporated age, sex, history of delivery of a macrosomic infant, obesity, sedentary lifestyle, and family history of diabetes. In a representative sample of the U.S. population, the sensitivity of the tree was 79%, the specificity was 65%, and the predictive value positive was 10%.

CONCLUSIONS

This classification tree performed significantly better than an existing questionnaire and should serve as a simple, noninvasive, and potentially cost-effective tool for diagnosing diabetes in the U.S.

Clusterin expression and apoptosis in tissue remodeling associated with renal regeneration

To analyze the role of clusterin in renal diseases involving a regenerative process, we have used a novel rodent model to compare temporal and spatial expression of clusterin mRNA. Thus, renal artery stenosis was used to induce unilateral non-infarctive renal atrophy. After several weeks, when cellular pathology of atrophic kidneys involved minimal apoptosis or inflammatory response and mitosis was at normal levels, regeneration of atrophic kidneys was stimulated by removal of the contralateral healthy kidneys. The regrowth response was very rapid and involved renal hyperplasia rather than hypertrophy. Regenerating kidneys were studied 0, 4, 8, 24 hours and 2, 3, 5, 7, and 14 days after contralateral nephrectomy. Several parameters were compared: level and localization of clusterin mRNA; cell proliferation; cell dedifferentiation and redifferentiation and apoptosis. During the acute regenerative phase (first 24 hr) clusterin expression was markedly increased, decreasing to untraceable levels by five days of regeneration. Clusterin mRNA was localized in dilated or collapsed atrophic tubules that had lost identifying surface structures of normal tubular epithelium (termed dedifferentiated). Clusterin was also localized in the periphery of some blood vessel walls. Cell proliferation peaked at three to five days of regeneration, and was also localized in dedifferentiated tubules. Despite the regenerative stimulus, an unexpected result was a transient but marked increase in apoptotic cell death in atrophic tubules in the first 24 hours of regeneration. Our results provide evidence of a temporal association between increased clusterin expression and apoptosis, but in situ localization showed clusterin mRNA over apparently viable, as well as apoptotic, cells in the epithelium of tubules showing clusterin expression. Clusterin mRNA was rarely identified over epithelial cells in foci of non-atrophic (non-dedifferentiated) nephrons that responded to the regenerative stimulus by cellular hypertrophy. The dramatic response after initiation of regeneration, especially the initiation of apoptosis in the tubular epithelium, may have applications for the study of genetic changes leading to renal oncogenesis.

Tumor progression and loss of heterozygosity at 5q and 18q in non-small cell lung cancer

We investigated the frequency and clinical significance of loss of heterozygosity (LOH) at the APC, MCC, and DCC tumor suppressor gene loci in 108 cases of resected non-small cell lung cancer (NSCLC). LOH at the APC/MCC gene cluster at chromosome 5q21 occurred frequently; it affected 29% of informative NSCLC cases and correlated with a significantly worse survival (P < 0.01). Furthermore, in the subtype most frequently affected (SCC), LOH at 5q not only correlated with a worse survival but also tumor involvement of the mediastinal and/or hilar nodes. In contrast, LOH at the DCC locus at chromosome 18q was far less frequent, occurring in 14% of NSCLC cases, and it was not associated with advanced stage or prognosis. These data suggest that LOH at 5q has a role in determining tumor progression and survival in NSCLC, and may prove to be a clinically useful prognostic indicator.

Homozygous intragenic deletion in the WT1 gene in a sporadic Wilms' tumour associated with high levels of expression of a truncated transcript

We have examined a panel of 21 sporadic Wilms' tumours for rearrangements in the Wilms' tumour suppressor gene, WT1. In one tumour with specific allele loss in chromosome 11p13, a homozygous deletion in the 3' end of the gene, encompassing exon 10 and the 3' untranslated region, was identified. High levels of a truncated WT1 transcript, predicted to encode a polypeptide missing the fourth zinc finger were expressed in this tumour. All other samples showed normal patterns of digestion on Southern blots. This observation confirms previous findings that large deletions in the gene occur infrequently in sporadic Wilms' tumours and that the zinc-finger region of the encoded polypeptide is critical for correct functioning of the gene.

Subcellular localisation of the antitumour drug mitoxantrone and the induction of DNA damage in resistant and sensitive human colon carcinoma cells

Cellular uptake and subcellular localisation of the antitumour agent mitoxantrone were studied in a human colon-carcinoma cell line and a mitoxantrone-resistant subline showing features consistent with an atypical multidrug-resistance phenotype involving altered topoisomerase II. Flow cytometry indicated a reduced uptake of mitoxantrone in the resistant line. Confocal microscopy indicated that mitoxantrone-associated fluorescence was primarily found within discrete cytoplasmic inclusions and around the periphery of the nucleus, with low levels being observed within the nucleus. The frequency of cytoplasmic inclusions was reduced in mitoxantrone-resistant cells as compared with parental cells. Fluorescence in cytoplasmic inclusions persisted throughout a 24-h post-treatment period in both cell lines. The results suggest that the persistence of mitoxantrone in cells is a determinant for the continuous induction of DNA damage, perhaps through chronic topoisomerase II trapping, and that modified sequestration may contribute to clinically relevant moderate levels of non-classic multidrug resistance.

Microsatellite instability and other molecular abnormalities in non-small cell lung cancer

Microsatellites are highly polymorphic, short-tandem repeat sequences dispersed throughout the genome. Instability of these repeat sequences at multiple genetic loci may result from mismatch repair errors and occur in hereditary nonpolyposis colorectal carcinoma and certain sporadic cancers. In non-small cell lung cancer, we found that microsatellite instability was infrequent, affecting only 7 (6.5%) of 108 cases. Despite being observed in all histological subtypes and at different tumor stages, microsatellite instability most commonly affected only one of the six loci tested on five chromosomal arms. In addition, microsatellite instability was associated with extensive, concurrent molecular changes including K-ras and p53 mutations as well as frequent loss of heterozygosity at chromosomal regions 5q, 8p, 9p, 11p, and 17p.

Analysis of paediatric tumour types associated with hemihyperplasia in childhood

In order to further explore the relationship between hemihyperplasia in children and the occurrence of embryonal tumours of childhood, the records at St Jude Children's Research Hospital were examined for patients who presented with a malignant tumour and hemihyperplasia. Of 27 evaluable patients, 19 had Wilm's tumour and one had massive bilateral nephroblastomatosis. The tumours were more likely to occur on the side affected by hemihyperplasia than to be found contralaterally. All but five of these patients developed the tumours before the age of six. Twenty-two of the 27 patients developed tumours associated with allelic loss on chromosome band 11p15, suggesting that the locus associated with hemihyperplasia may be also located at chromosome band 11p15.

Etoposide-induced cell cycle delay and arrest-dependent modulation of DNA topoisomerase II in small-cell lung cancer cells

As an approach to the rational design of combination chemotherapy involving the anti-cancer DNA topoisomerase II poison etoposide (VP-16), we have studied the dynamic changes occurring in small-cell lung cancer (SCLC) cell populations during protracted VP-16 exposure. Cytometric methods were used to analyse changes in target enzyme availability and cell cycle progression in a SCLC cell line, mutant for the tumour-suppressor gene p53 and defective in the ability to arrest at the G1/S phase boundary. At concentrations up to 0.25 microM VP-16, cells became arrested in G2 by 24 h exposure, whereas at concentrations 0.25-2 microM G2 arrest was preceded by a dose-dependent early S-phase delay, confirmed by bromodeoxyuridine incorporation. Recovery potential was determined by stathmokinetic analysis and was studied further in aphidicolin-synchronised cultures released from G1/S and subsequently exposed to VP-16 in early S-phase. Cells not experiencing a VP-16-induced S-phase delay entered G2 delay dependent upon the continued presence of VP-16. These cells could progress to mitosis during a 6-24 h period after drug removal. Cells experiencing an early S-phase delay remained in long-term G2 arrest with greatly reducing ability to enter mitosis up to 24 h after removal of VP-16. Irreversible G2 arrest was delimited by the induction of significant levels of DNA cleavage or fragmentation, not associated with overt apoptosis, in the majority of cells. Western blotting of whole-cell preparations showed increases in topoisomerase II levels (up to 4-fold) attributable to cell cycle redistribution, while nuclei from cells recovering from S-phase delay showed enhanced immunoreactivity with an anti-topoisomerase II alpha antibody. The results imply that traverse of G1/S and early S-phase in the presence of a specific topoisomerase II poison gives rise to progressive low-level trapping of topoisomerase II alpha, enhanced topoisomerase II alpha availability and the subsequent irreversible arrest in G2 of cells showing limited DNA fragmentation. We suggest that protracted, low-dose chemotherapeutic regimens incorporating VP-16 are preferentially active towards cells attempting G1/S transition and have the potential for increasing the subsequent action of other topoisomerase II-targeted agents through target enzyme modulation. Combination modalities which prevent such dynamic changes occurring would act to reduce the effectiveness of the VP-16 component.

Multilevel therapeutic targeting by topoisomerase inhibitors

The successful use of cytotoxic agents in the clinical management of LCH depends upon the selective targeting of cells participating in the disease process. The topoisomerase 'poisons', currently used extensively in the treatment of aggressive malignancies, represent an intriguing class of cytotoxic agents exerting their cytostatic and cytotoxic effects at multiple levels according to cell type. The non-DNA intercalating topoisomerase II poison, etoposide (VP-16), is the "drug of first choice" in the treatment of LCH by cytotoxic chemotherapy. This major anticancer agent traps the nuclear enzyme DNA topoisomerase II on DNA in a sequence-specific manner, the processing of trapped complexes giving rise to a plethora of cellular effects not least the potential activation of pathways leading to cell cycle arrest and apoptosis. This short review describes the principles of topoisomerase inhibition, the multiplicity of cellular effects and the concept of cellular targeting in LCH. The successful treatment of LCH by cytotoxic chemotherapy will depend on both the identity of the target tissues and a clear view of therapeutic intent, given the potential for induction of haematological neoplasia.

Correlation of loss of heterozygosity at 11p with tumour progression and survival in non-small cell lung cancer

Loss of heterozygosity (LOH) affecting loci at 11p13 and 11p15 occurs in childhood and adult carcinomas, including non-small cell lung cancer (NSCLC). In NSCLC, the highest reported frequency of LOH was 72% at the 11p13 catalase (CAT) locus. As this locus is centromeric to the Wilms' tumour (WT1) locus, possible involvement of WT1 in the pathogenesis of NSCLC was considered. We thus examined 101 cases of NSCLC for LOH at the WT1 and five other polymorphic loci along 11p. At 11p13, the frequencies of LOH were 20% (9/46) at the FSHB locus, 9% (5/53) at the WT1 locus, and 15% (6/41) at the CAT locus. The shortest region of overlap (SRO) at 11p13 was mapped centromeric to, but excluding, the WT1 locus. Only adenocarcinomas showed LOH in this region. At 11p15, LOH affected 23% (18/77) of informative cases, with the highest frequency of 36% at the insulin (INS) locus. The SRO at 11p15 was mapped telomeric to the RRM1 locus. A third region, at 11p13-15 between WT1 and RRM1, was also affected by LOH. LOH at 11p correlated significantly with advanced T stage and nodal involvement in NSCLC tumours. In the squamous cell carcinoma subtype, LOH along 11p also correlated with nodal involvement. Furthermore, squamous tumours with LOH involving 11p13 loci had significantly worse survival than those without LOH. These data suggest that tumor suppressor gene(s) on 11p affect the progression of NSCLC, particularly squamous cell carcinomas.