Dose-dependent activity of pyrazinamide in animal models of intracellular and extracellular tuberculosis infections

Recent in vitro pharmacokinetic data suggest that the currently recommended dose of pyrazinamide may be suboptimal for killing intracellular bacilli in humans. We evaluated a range of pyrazinamide doses against intracellular and extracellular Mycobacterium tuberculosis in chronically infected mice and guinea pigs, respectively. Antibiotics were given five times weekly for 4 weeks beginning 28 days after infection. Human-equivalent doses of isoniazid reduced lung bacterial counts 10-fold in each species. Pyrazinamide given at 1/4 and 1/2 the human-equivalent dose was minimally active, while human-equivalent doses reduced lung bacterial counts by ～1.0 log(10) in each species. Doubling the human-equivalent dose of pyrazinamide reduced the lung bacillary burden by 1.7 and 3.0 log(10) in mice and guinea pigs, respectively. As in humans and mice, pyrazinamide showed significant synergy with rifampin in guinea pigs. Clinical studies are warranted to investigate the sterilizing activity and tolerability of higher doses of pyrazinamide in combination tuberculosis regimens.     

Inflammation and dyslipidaemia: a possible interplay between established risk factors in North Indian males with coronary artery disease

Objectives

Coronary artery disease (CAD) is a leading cause of morbidity and mortality in the developed world and is rapidly assuming epidemic proportions in developing countries, including India. This has led to extensive research to determine the risk factors and the pathways that may predispose to the elevated risk of this disease. Important among them include lipoproteins, homocysteine, lipoprotein (a), pro-inflammatory cytokines and others. The following study was undertaken to determine a possible inter-relationship between inflammation and dyslipidaemia, which are important risk factors for CAD in the atherosclerosis-prone North Indian male population.

Methods

The study groups comprised 150 clinically assessed North Indian male patients with acute myocardial infarction (AMI), diagnosed on electrocardiographic and biochemical criteria, and 150 healthy controls. Apolipoprotein-AI (Apo-AI), apolipoprotein-B (Apo-B) and C-reactive protein (CRP) levels were estimated using kits based on the immunoturbidimetric assay from Randox, UK. Tumour necrosis factor-α (TNF-α) and lipoprotein (a) were assayed using commercially available ELISA kits from Diaclone Research, Belgium and Innogenetics, Belgium, respectively.

Results

The patients with AMI showed highly significant elevations in the levels of total serum cholesterol, triglycerides, LDL cholesterol, Apo-B and a significant decline in HDL cholesterol, compared with healthy controls. Significantly elevated serum levels of inflammatory markers, TNF-α and CRP were seen in patients with AMI, compared to the control subjects. A significantly positive correlation of TNF-α was observed with lipoprotein (a) in patients with CAD.

Conclusion

The data clearly underlines a possible interplay between inflammation and dyslipidaemia in the pathogenesis of CAD in the Indian context. This insight into the aetiopathogenesis of CAD will prove highly beneficial for devising better preventive measures and pharmacological interventions for CAD.     

Involvement of MT1‐MMP and TIMP‐2 in human periodontal disease

Oral Diseases (2010) 16 , 388–395 Objectives: Periodontal disease is characterized by an increased collagen metabolism. Although membrane type‐1 matrix metalloproteinase (MT1‐MMP) plays a critical role in collagen degradation, its involvement in human periodontitis remains to be determined. Methods: MT1‐MMP and TIMP‐2 expression and distribution were evaluated in gingival tissue samples derived from 10 healthy and 12 periodontitis‐affected human subjects. MT1‐MMP and TIMP‐2 expression were assessed through Western‐blot of tissue homogenates. The main cell types involved in MT1‐MMP and TIMP‐2 production were evaluated by means of immunohistochemistry. Results: Both MT1‐MMP and TIMP‐2 were significantly increased in periodontitis‐affected gingival tissues when compared to healthy gingiva. Moreover, the balance between MT1‐MMP and its inhibitor TIMP‐2 was altered in periodontitis‐affected tissues, suggesting an imbalance in this proteolytic axis. Immunohistochemistry demonstrated the expression of MT1‐MMP in fibroblasts and macrophages in gingival tissues. MT1‐MMP was detected in cells in close association with the gingival collagen matrix. TIMP‐2 expression was identified in fibroblasts, macrophages and epithelial cells. Conclusions: Our observations show an increased expression of MT1‐MMP and TIMP‐2 in periodontitis‐affected gingival tissues. The altered balance between these two molecular mediators of collagen remodeling suggests their involvement in human periodontal disease.     

The Impact on Morbidity and Length of Stay of Early Versus Delayed Complete Lymphadenectomy in Melanoma: Results of the Multicenter Selective Lymphadenectomy Trial (I)

Background

Complete lymph node dissection, the current standard treatment for nodal metastasis in melanoma, carries the risk of significant morbidity. Clinically apparent nodal tumor is likely to impact both preoperative lymphatic function and extent of soft tissue dissection required to clear the basin. We hypothesized that early dissection would be associated with less morbidity than delayed dissection at the time of clinical recurrence.

Materials and Methods

The Multicenter Selective Lymphadenectomy Trial I randomized patients to wide excision of a primary melanoma with or without sentinel lymph node biopsy. Immediate completion lymph node dissection (early CLND) was performed when indicated in the SLN arm, while therapeutic dissection (delayed CLND) was performed at the time of clinical recurrence in the wide excision-alone arm. Acute and chronic morbidities were prospectively monitored.

Results

Early CLND was performed in 225 patients, and in the wide excision-alone arm 132 have undergone delayed CLND. The 2 groups were similar for primary tumor features, body mass index, basin location, and demographics except age, which were higher for delayed CLND. The number of nodes evaluated and the number of positive nodes was greater for delayed CLND. There was no significant difference in acute morbidity, but lymphedema was significantly higher in the delayed CLND group (20.4% vs. 12.4%, P = .04). Length of inpatient hospitalization was also longer for delayed CLND.

Conclusion

Immediate nodal treatment provides critical prognostic information and a likely therapeutic effect for those patients with nodal involvement. These data show that early CLND is also less likely to result in lymphedema.     

Manganese intake and cholestatic jaundice in neonates receiving parenteral nutrition: a randomized controlled study

Infants requiring parenteral nutrition (n = 244) were randomized to receive either 1 (group 1, n = 121) or 0.0182 micromol/kg/d (group 2, n = 123) of manganese supplementation. The whole-blood manganese and serum direct bilirubin concentrations of the infants were monitored, as was the development of cholestasis (peak serum direct bilirubin concentration >50 micromol/L). Subgroup analysis was carried out on the data of 78 infants in group 1 and 82 in group 2 who had received manganese supplementation and more than three-quarters of their total daily fluid as parenteral nutrition for >14 d. Of all the infants randomized, the high manganese group (group 1) showed a trend towards developing higher peak whole-blood manganese concentration [group 1 versus group 2: median (interquartile range): 606.0 (421.0; 1005.0) vs 566.0 (336.0: 858.0); p=0.061] and higher peak serum direct bilirubin concentration [37.0 (10.5; 122.5) vs 19.0 (8.0; 112.5); p=0.153], but the differences between the 2 groups did not reach statistical significance. The 2 groups did not differ in terms of the occurrence of cholestasis during parenteral nutrition (63/121 vs 57/123; p=0.444). Subgroup analysis of infants who had received more than three-quarters of their total daily fluid as parenteral nutrition showed, however, that the high manganese group developed significantly higher whole-blood manganese concentration [743.5 (498.0; 1211.0) vs 587.0 (438.0; 982.0); p=0.037] and serum direct bilirubin concentration [84.0 (28.0; 170.0) vs 25.5 (9.0; 117.0): p < 0.001]. Although there was no significant difference in the occurrence of cholestasis (58/78 vs 49/82; p = 0.073), more infants in the high manganese group developed a more severe degree of direct hyperbilirubinaemia, with peak serum direct bilirubin >100 micromol/L (32/78 vs 20/82; p = 0.038). Conclusion: We conclude that the pathogenesis of parenteral nutrition-related cholestasis is probably multifactorial, and that high manganese intake is a significant contributory factor.