Route of transmission might influence the clinical expression of periodontal lesions in "human immunodeficiency virus" positive patients.

BACKGROUND: Various routes have been reported with respect to the transmission of human immunodeficiency virus (HIV) from one individual to another. But it is not clear whether they alter the clinical expression of the disease. This study was conducted to know whether there exists any difference in the occurrence of periodontal lesions among untreated HIV subjects who acquired the disease either through intravenous drug abuse or sexual contact and to correlate those lesions with immune suppression as indicated by CD 4 T lymphocyte counts. MATERIALS AND METHODS: In this cross-sectional study 213 HIV-positive subjects who had not started on Highly Active Anti Retroviral Therapy (HAART) were selected and divided into two groups intravenous drug users (IVDU) and non-IVDU (NIVDU). CD 4 T lymphocyte counts were evaluated and clinical examination was done to detect the presence of pathologic periodontal lesions. RESULTS: Mean probing depth (PD) and clinical attachment level (CAL) are significantly higher in drug users than nondrug users. When periodontal lesions are compared with CD 4 cell counts, it is found that significant inverse relation exists between linear gingival erythema, necrotizing ulcerative periodontitis, and CD 4 counts, but only in nondrug users. CONCLUSION: An inverse correlation between linear gingival erythema, necrotizing ulcerative periodontitis, and CD 4 counts in NIVDU indicating their reliability as a marker for immune suppression. Periodontitis is more prevalent among drug users indicating some difference in disease expression among the groups.

In vitro glucuronidation of the antibacterial triclocarban and its oxidative metabolites.

Triclocarban (3,4,4'-trichlorocarbanilide; TCC) is widely used as an antibacterial in bar soaps. During use of these soaps, a significant portion of TCC is absorbed by humans. For the elimination from the body, glucuronidation plays a key role in both biliary and renal clearance. To investigate this metabolic pathway, we performed microsomal incubations of TCC and its hydroxylated metabolites 2'-OH-TCC, 3'-OH-TCC, and 6-OH-TCC. Using a new liquid chromatography-UV-mass spectrometry method, we could show a rapid glucuronidation for all OH-TCCs by the uridine-5'-diphosphate-glucuronosyltransferases (UGT) present in liver microsomes of humans (HLM), cynomolgus monkeys (CLM), rats (RLM), and mice (MLM). Among the tested human UGT isoforms, UGT1A7, UGT1A8, and UGT1A9 showed the highest activity for the conjugation of hydroxylated TCC metabolites followed by UGT1A1, UGT1A3, and UGT1A10. Due to this broad pattern of active UGTs, OH-TCCs can be efficiently glucuronidated in various tissues, as shown for microsomes from human kidney (HKM) and intestine (HIM). The major renal metabolites in humans, TCC-N-glucuronide and TCC-N'-glucuronide, were formed at very low conversion rates (<1%) by microsomal incubations. Low amounts of N-glucuronides were generated by HLM, HIM, and HKM, as well as by MLM and CLM, but not by RLM, according to the observed species specificity of this metabolic pathway. Among the human UGT isoforms, only UGT1A9 had activity for the N-glucuronidation of TCC. These results present an anomaly where in vivo the predominant urinary metabolites of TCC are N and N'-glucuronides, but these compounds are slowly produced in vitro.

Modification of osteoarthritis in the guinea pig with pulsed low-intensity ultrasound treatment.

OBJECTIVE: The Hartley guinea pig develops articular cartilage degeneration similar to that seen in idiopathic human osteoarthritis (OA). We investigated whether the application of pulsed low-intensity ultrasound (PLIUS) to the Hartley guinea pig joint would prevent or attenuate the progression of this degenerative process. METHODS: Treatment of male Hartley guinea pigs was initiated at the onset of degeneration (8 weeks of age) to assess the ability of PLIUS to prevent OA, or at a later age (12 months) to assess the degree to which PLIUS acted to attenuate the progression of established disease. PLIUS (30 mW/cm(2)) was applied to stifle joints for 20 min/day over periods ranging from 3 to 10 months, with contralateral limbs serving as controls. Joint cartilage histology was graded according to a modified Mankin scale to evaluate treatment effect. Immunohistochemical staining for interleukin-1 receptor antagonist (IL-1ra), matrix metalloproteinase (MMP)-3, MMP-13, and transforming growth factor (TGF)-beta1 was performed on the cartilage to evaluate patterns of expression of these proteins. RESULTS: PLIUS did not fully prevent cartilage degeneration in the prevention groups, but diminished the severity of the disease, with the treated joints showing markedly decreased surface irregularities and a much smaller degree of loss of matrix staining as compared to controls. PLIUS also attenuated disease progression in the groups with established disease, although to a somewhat lesser extent as compared to the prevention groups. Immunohistochemical staining demonstrated a markedly decreased degree of TGF-beta1 production in the PLIUS-treated joints. This indicates less active endogenous repair, consistent with the marked reduction in cartilage degradation. CONCLUSIONS: PLIUS exhibits the ability to attenuate the progression of cartilage degeneration in an animal model of idiopathic human OA. The effect was greater in the treatment of early, rather than established, degeneration.

Variable-number tandem repeats that are useful in genotyping isolates of Salmonella enterica subsp. enterica serovars Typhimurium and Newport.

The genome of Salmonella enterica subsp. enterica serovar Typhimurium strain LT2 was analyzed for direct repeats, and 54 sequences containing variable-number tandem repeat loci were identified. Ten primer pairs that anneal upstream and downstream of each selected locus were designed and used to amplify PCR targets in isolates of S. enterica serovars Typhimurium and Newport. Four of the 10 loci did not show polymorphism in the length of products. Six loci were selected for analysis. Isolates of S. enterica serovars Typhimurium and Newport that were related to specific outbreaks and showed identical pulsed-field gel electrophoresis patterns were indistinguishable by the length of the six variable-number tandem repeats. Isolates that differed in their pulsed-field gel electrophoresis patterns showed polymorphism in variable-number tandem repeat profiles. Length of the products was confirmed by DNA sequence analysis. Only 2 of the 10 loci contained exact integers of the direct repeat. Eight loci contained partial copies. The partial copies were maintained at the ends of the variable-number tandem repeat loci in all isolates. In spite of having partial copies that were maintained in all isolates, the number of direct repeats at a locus was polymorphic. Six variable-number tandem repeat loci were useful in distinguishing isolates of S. enterica serovars Typhimurium and Newport that had different pulsed-field gel electrophoresis patterns and in identifying outbreak-associated cases that shared a common pulsed-field gel pattern.

Interaction studies on proteins encoded by the phthiocerol dimycocerosate locus of Mycobacterium tuberculosis.

Polyketide synthases (PKSs) of Mycobacterium tuberculosis are increasingly being seen as producers of virulence factors that are important for pathogenesis by the bacterium. Thus, the phenolphthiocerol synthase PKS cluster of M. tuberculosis is responsible, in part, for the synthesis of a virulence determinant called phthiocerol dimycocerosate (PDIM). Here, we provide evidence that the PpsE protein, which is part of that cluster, interacts with the type II thioesterase TesA of M. tuberculosis. The interaction was demonstrated by employing a two-hybrid system, and confirmed using a GST (glutathione S-transferase) pull-down' assay after both proteins had been purified to homogeneity. Based on the present findings, a revised model for the processing of polyketides during the synthesis of PDIM is presented.

Cyanurate mimics of hydrogen-bonding patterns of nucleic bases: crystal structure of a 1:1 molecular complex of 9-ethyladenine and N-methylcyanuric acid.

[figure: see text] 9-Ethyladenine forms a unique molecular complex with N-methylcyanuric acid consisting of homomeric and heteromeric hydrogen-bonding patterns. Also, the homomeric hydrogen bond pattern is different than that observed in its pure crystal structures.

Molecular basis of Celmer's rules: role of the ketosynthase domain in epimerisation and demonstration that ketoreductase domains can have altered product specificity with unnatural substrates.

BACKGROUND: Polyketides are structurally diverse natural products with a range of medically useful activities. Non-aromatic bacterial polyketides are synthesised on modular polyketide synthase multienzymes (PKSs) in which each cycle of chain extension requires a different 'module' of enzymatic activities. Attempts to design and construct modular PKSs that synthesise specified novel polyketides provide a particularly stringent test of our understanding of PKS structure and function. RESULTS: We show that the ketoreductase (KR) domains of modules 5 and 6 of the erythromycin PKS, housed in the multienzyme subunit DEBS3, exert an unexpectedly low level of stereochemical control in reducing the keto group of a synthetic analogue of the diketide intermediate. This led us to construct a hybrid triketide synthase based on DEBS3 with ketosynthase domain ketosynthase (KS)5 replaced by the loading module and KS1. The construct in vivo produced two major triketide stereoisomers, one expected and one surprising. The latter was of opposite configuration at three out of the four chiral centres: the branching alkyl centre was that produced by KS1 and, surprisingly, both hydroxyl centres produced by the reduction steps carried out by KR5 and KR6 respectively. CONCLUSIONS: These results demonstrate that the epimerising activity associated with module 1 of the erythromycin PKS can be conferred on module 5 merely by transfer of the KS1 domain. Moreover, the normally precise stereochemical control observed in modular PKSs is lost when KR5 and KR6 are challenged by an unfamiliar substrate, which is much smaller than their natural substrates. This observation demonstrates that the stereochemistry of ketoreduction is not necessarily invariant for a given KR domain and underlines the need for mechanistic understanding in designing genetically engineered PKSs to produce novel products.

Manganese superoxide dismutase signals matrix metalloproteinase expression via H2O2-dependent ERK1/2 activation.

Manganese-superoxide dismutase (Sod2) removes mitochondrially derived superoxide (O(2)) at near-diffusion limiting rates and is the only antioxidant enzyme whose expression is regulated by numerous stimuli. Here it is shown that Sod2 also serves as a source of the intracellular signaling molecule H(2)O(2). Sod2-dependent increases in the steady-state levels of H(2)O(2) led to ERK1/2 activation and subsequent downstream transcriptional increases in matrix metalloproteinase-1 (MMP-1) expression, which were reversed by expression of the H(2)O(2)-detoxifying enzyme, catalase. In addition, a single nucleotide polymorphism has recently been identified (1G/2G) at base pair--1607 that creates an Ets site adjacent to an AP-1 site at base pair --1602 and has been shown to dramatically enhance transcription of the MMP-1 promoter. Luciferase promoter constructs containing either the 1G or 2G variation were 25- or 1000-fold more active when transiently transfected into Sod2-overexpressing cell lines, respectively. The levels of MMP-2, -3, and -7 were also increased in the Sod2-overexpressing cell lines, suggesting that Sod2 may function as a "global" redox regulator of MMP expression. In addition, Sod2(-/+) mouse embryonic fibroblasts failed to respond to the cytokine-mediated induction of the murine functional analog of MMP-1, MMP-13. This study provides evidence that the modulation of Sod2 activity by a wide array of pathogenic and inflammatory stimuli may be utilized by the cell as a primary signaling mechanism leading to matrix metalloproteinase expression.

Knowledge-based design of bimodular and trimodular polyketide synthases based on domain and module swaps: a route to simple statin analogues.

BACKGROUND: Polyketides are structurally diverse natural products that have a range of medically useful activities. Nonaromatic bacterial polyketides are synthesised on modular polyketide synthase (PKS) multienzymes, in which each cycle of chain extension requires a different 'module' of enzymatic activities. Attempts to design and construct modular PKSs that synthesise specified novel polyketides provide a particularly stringent test of our understanding of PKS structure and function. RESULTS: We have constructed bimodular and trimodular PKSs based on DEBS1-TE, a derivative of the erythromycin PKS that contains only modules 1 and 2 and a thioesterase (TE), by substituting multiple domains with appropriate counterparts derived from the rapamycin PKS. Hybrid PKSs were obtained that synthesised the predicted target triketide lactones, which are simple analogues of cholesterol-lowering statins. In constructing intermodular fusions, whether between modules in the same or in different proteins, it was found advantageous to preserve intact the acyl carrier protein-ketosynthase (ACP-KS) didomain that spans the junction between successive modules. CONCLUSIONS: Relatively simple considerations govern the construction of functional hybrid PKSs. Fusion sites should be chosen either in the surface-accessible linker regions between enzymatic domains, as previously revealed, or just inside the conserved margins of domains. The interaction of an ACP domain with the adjacent KS domain, whether on the same polyketide or not, is of particular importance, both through conservation of appropriate protein-protein interactions, and through optimising molecular recognition of the altered polyketide chain in the key transfer of the acyl chain from the ACP of one module to the KS of the downstream module.

Laryngeal preservation by treatment with induction chemotherapy and radiotherapy protocol for stage III & IV carcinoma larynx--results of a pilot study.

Total laryngectomy for advanced carcinoma of the larynx is effective but functionally disabling. In an effort at laryngeal preservation, 33 patients of stage III/IV carcinoma larynx were treated between 1987 and 1991 with induction chemotherapy followed by definitive radiation. Two chemotherapy protocols were administered. Group I patients received one to three cycles of cisplatin 100 mg/m2 (day 1), bleomycin 15 U/m2 (day 1), and 5-fluorouracil 1000 mg/m2/day (day 2 to 5) at three weekly intervals. This was then followed by radiotherapy. Group II received one to six weekly injections of single agent methotrexate 50 mg/m2 with or without leucocovorin rescue followed by radiotherapy. Any recurrence was salvaged by surgery. Midway through the study, Group II protocol was discontinued as the initial results were not comparable with Group I or standard treatment. The Group I protocol, however, yielded an initial locoregional control rate of 83.3 per cent With the addition of surgical salvage the locoregional control rate was 94.4 per cent and the control rate with laryngeal preservation was 88.8 per cent. The Kaplan-Meier probability of two years and five years disease-free survival was 81.9 per cent and 61.4 per cent respectively. For disease-free survival with laryngeal preservation the corresponding figures for two years and five years were 58.3 per cent and 41.7 per cent. The control group of 51 patients treated with radical surgery followed by radiotherapy yielded survival figures at two years and five years of 64.3 per cent and 57.2 per cent. The difference in the survival of Group I and the control group was not statistically significant (p value = 0.280). These initial results indicate that for stage III and for surgically resectable stage IV laryngeal carcinomas, a protocol of induction combination chemotherapy consisting of cisplatin, bleomycin and 5-fluorouracil followed by radiotherapy and combined with surgical salvage whenever required, can lead to comparable cure rates. In addition, a large proportion of patients are spared the morbidity of a total laryngectomy.

Panic disorder: a different perspective.

Panic disorder is a chronic and debilitating illness. In this article, we present an algorithm of the diagnosis and treatment of the illness. We place much importance upon the patient variables associated with the treatment decisions. We emphasize strong patient involvement in treatment as a way to become panic free and improve level of functioning. Panic disorder is defined in DSM-IV1 as "The presence of recurrent panic attacks followed by at least one month of persistent concern about having another panic attack, worry about the possible implications or consequences of the panic attack, or a significant behavioral change related to the attacks." A panic attack is defined as "a discrete period of intense fear or discomfort, in which four or more of the following symptoms developed abruptly and reached a peak within 10 minutes." 1) Palpitations, pounding heart or accelerated heart rate; 2) sweating; 3) trembling or shaking; 4) sensations of shortness of breath or smothering; 5) feeling of choking; 6) chest pain or discomfort; 7) nausea or abdominal distress; 8) feeling dizzy, unsteady, light-headed or faint; 9) derealization or depersonalization; 10) fear of losing control or going crazy; 11) fear of dying; 12) paresthesias; 13) chills or hot flashes. The following hypotheses have been used to conceptualize panic disorder from a psychiatrist's perspective.

Strongyloides stercoralis infection in AIDS.

Strongyloides stercoralis infection in humans continues to be a subject that has frequently inspired reviews and papers. Within the AIDS epidemic, interest gathered momentum with the inclusion of this infection in the indicator diseases list, and its subsequent removal 5 years later by the CDC. These actions have prompted a debate as to whether this infection has special significance in patients with AIDS and whether its exclusion from the CDC criteria is justified. A detailed review of the world literature reveals an increased awareness and diagnosis of this infection in patients with AIDS which takes the form of dissemination, a rapid course, and a usually fatal outcome.