Faculty Bibliography

BACKGROUND: A 1991 survey showed high levels of drug resistance among tuberculosis patients in New York, NY. As a result, the tuberculosis control program was strengthened, including expanded use of directly observed therapy and improved infection control. METHODS: We collected isolates from every patient in New York City with a positive culture for Mycobacterium tuberculosis during April 1994; results were compared with those in the April 1991 survey. RESULTS: From 1991 to 1994, the number of patients decreased from 466 to 332 patients. The percentage with isolates resistant to 1 or more antituberculosis drugs decreased from 33% to 24% (P < .01); with isolates resistant to at least isoniazid decreased from 26% to 18% (P < .05); and with isolates resistant to both isoniazid and rifampin decreased from 19% to 13% (P < .05). The number of patients with isolates resistant to both isoniazid and rifampin decreased by more than 50%. Among never previously treated patients, the percentage with resistance to 1 or more drugs decreased from 22% in 1991 to 13% in 1994 (P < .05). The number of patients with consistently positive culture results for more than 4 months decreased from 130 to 44. A history of antituberculosis treatment was the strongest predictor of drug resistance (odds ratio = 3.1; P < .001). Human immunodeficiency virus infection was associated with drug resistance among patients who never had been treated for tuberculosis. CONCLUSIONS: Drug-resistant tuberculosis declined significantly in New York City from 1991 to 1994. Measures to control and prevent tuberculosis were associated with a 29% decrease in the proportion of drug resistance and a 52% decrease in the number of patients with multidrug-resistant tuberculosis

A gene (pncA) with mutations associated with pyrazinamide resistance in Mycobacterium tuberculosis complex members was characterized in 67 pyrazinamide-resistant and 51 pyrazinamide-susceptible isolates recovered from diverse geographic localities and anatomic sites and typed by IS6110 profiling. All pyrazinamide-susceptible organisms had identical pncA alleles. In striking contrast, 72% of the 67 resistant organisms had pncA mutations that altered the primary amino acid sequence of pyrazinamidase. A total of 17 previously undescribed mutations were found, including upstream mutations, missense changes, nucleotide insertions and deletions, and termination mutations. The mutations were arrayed along virtually the entire length of the gene. These data are further evidence that most drug resistance in M. tuberculosis is due to simple mutations occurring in chromosomally encoded genes rather than to acquisition of resistance genes by horizontal transfer events

The Mycobacterium tuberculosis H37Rv efpA gene encodes a putative efflux protein, EfpA, of 55,670 Da. The deduced EfpA protein was similar in secondary structure to Pur8, MmrA, TcmA, LfrA, EmrB, and other members of the QacA transporter family (QacA TF) which mediate antibiotic and chemical resistance in bacteria and yeast. The predicted EfpA sequence possessed all transporter motifs characteristic of the QacA TF, including those associated with proton-antiport function and the motif considered to be specific to exporters. The 1,590-bp efpA open reading frame was G+C rich (65%), whereas the 40-bp region immediately upstream had an A+T bias (35% G+C). Reverse transcriptase-PCR assays indicated that efpA was expressed in vitro and in situ. Putative promoter sequences were partially overlapped by the A+T-rich region and by a region capable of forming alternative secondary structures indicative of transcriptional regulation in analogous systems. PCR single-stranded conformational polymorphism analysis demonstrated that these upstream flanking sequences and the 231-bp, 5' coding region are highly conserved among both drug-sensitive and multiply-drug-resistant isolates of M. tuberculosis. The efpA gene was present in the slow-growing human pathogens M. tuberculosis, Mycobacterium leprae, and Mycobacterium bovis and in the opportunistic human pathogens Mycobacterium avium and Mycobacterium intracellular. However, efpA was not present in 17 other opportunistically pathogenic or nonpathogenic mycobacterial species

Large-cell change of hepatocytes (LCC), also called liver cell dysplasia of large-cell type, is a set of cytologic changes comprising nuclear and cytoplasmic enlargement, nuclear pleomorphism, and multinucleation. This entity is encountered frequently on histologic or cytologic examination of specimens obtained from livers with a variety of chronic diseases and originally was thought to have a premalignant nature. Accumulating evidence, however, now suggests that LCC is merely a reactive change. Having often observed LCC in liver specimens with chronic biliary tract disease, that is, in livers where cholestasis preceded hepatocyte injury, we surmised that LCC may be a result of prolonged cholestasis. To determine whether there was any association between LCC and cholestasis, we examined microscopically a series of 400 nodules from 40 consecutive adult cirrhotic livers, resected on transplantation, and graded LCC and cholestasis semiquantitatively. LCC was present diffusely in cirrhotic nodules of 25 specimens (62.5%). Nine additional specimens (22.5%) had focal mild LCC. Usually, LCC and cholestasis occurred together, in the same cirrhotic nodules and in the same areas of nodules. There was a statistically significant association between the presence and grade of LCC and those of cholestasis (p < 0.0001; chi-square test). Within etiological categories of cirrhosis (chronic hepatitis; n = 28; alcoholic liver disease; n = 6; biliary disease: n = 6), the significance was maintained. We conclude that, in cirrhosis of different etiologies, LCC may represent a reactive change that results from prolonged cytoplasmic cholestasis

To study local structures in proteins, we previously developed an autoassociative artificial neural network (autoANN) and clustering tool to discover intrinsic features of macromolecular structures. The hidden unit activations computed by the trained autoANN are a convenient low-dimensional encoding of the local protein backbone structure. Clustering these activation vectors results in a unique classification of protein local structural features called Structural Building Blocks (SBBs). Here we describe application of this method to a larger database of proteins, verification of the applicability of this method to structure classification, and subsequent analysis of amino acid frequencies and several commonly occurring patterns of SBBs. The SBB classification method has several interesting properties: 1) it identifies the regular secondary structures, alpha helix and beta strand; 2) it consistently identifies other local structure features (e.g., helix caps and strand caps); 3) strong amino acid preferences are revealed at some positions in some SBBs; and 4) distinct patterns of SBBs occur in the 'random coil' regions of proteins. Analysis of these patterns identifies interesting structural motifs in the protein backbone structure, indicating that SBBs can be used as 'building blocks' in the analysis of protein structure. This type of pattern analysis should increase our understanding of the relationship between protein sequence and local structure, especially in the prediction of protein structures

Twenty-six patients with Grade III acromioclavicular joint separations were evaluated to determine the outcomes of nonoperative and operative management. Evaluation consisted of a detailed functional questionnaire, physical examination, and comprehensive isokinetic strength assessment. The patients were divided into two groups: operative (n = 16) and nonoperative (n = 10). Operative management consisted of coracoclavicular stabilization with heavy suture material and with nine of the sixteen patients treatment also consisted of coracoacromial ligament transfer and lateral clavicle resection. Nonoperative management consisted of short-term immobilization with early range of motion and rehabilitation. The two groups were similar in all characteristics except mean age: 30.7 years for the operative group and 49.6 years for the nonoperative group. Follow-up evaluation was performed an average of 32.9 months after either injury (nonoperative group) or surgery. Our results indicated that nonoperative management was superior to operative management with respect to time to return to work (0.8 months vs. 2.6 months), time to return to athletics (3.5 months vs. 6.4 months) and time of immobilization (2.7 weeks vs. 6.2 weeks). However, operative management was superior to nonoperative management in the following parameters: time to attain completely pain-free status, the patient's subjective impression of pain, range of motion, functional limitations, cosmesis, and long-term satisfaction. There were no significant differences between the two groups with respect to shoulder range of motion, manual muscle testing, or neurovascular findings. Isokinetic strength testing of the involved shoulder, expressed as a percentage of the uninvolved shoulder, showed no significant differences in peak torque, total work, or total power between the operative and nonoperative groups. However, comparison of the involved to the uninvolved extremity within each group did reveal a trend toward decreased peak torque, work, and power for abduction in the involved extremity regardless of the treatment used. These findings reached statistical significance only for power at the slower testing speed (60 degrees/sec). There was also a significant decrease in power in the involved extremity for external rotation at the faster speed (120 degrees/sec) in the nonoperative group. Finally, the absolute values for peak torque, work, and power were significantly greater for all motions tested in the operative group as compared to the nonoperative group. This may reflect the difference in age between the two groups. Based upon the patients studied, there are benefits to both nonoperative and operative methods of treatment of Grade III acromioclavicular separations. Recovery of strength did not differ between the two groups and therefore should be viewed as a less important factor in patient selection for operative versus nonoperative management. Careful patient selection should remain an important aspect of treatment for this controversial injury