Alterations in the superoxide dismutase gene of an isoniazid-resistant strain of Mycobacterium tuberculosis.

Genetic analysis of a set of six Mycobacterium tuberculosis strains differing in virulence for the guinea pig revealed an altered restriction enzyme fragmentation pattern associated with the superoxide dismutase (SOD) gene in a low-virulence, isoniazid-resistant strain. In addition, it was found that the SOD enzyme produced by the isoniazid-resistant strain differed in its electrophoretic mobility from the SOD of other M. tuberculosis strains. Detailed analysis of these strain-specific differences showed that the restriction fragment length polymorphism resulted from the presence of a copy of a repetitive element 552 bp upstream of the SOD gene and that the anomalous electrophoretic mobility arose from a single nucleotide change, resulting in replacement of an aspartic acid residue by histidine in the SOD enzyme of the isoniazid-resistant strain. Possible relationships between genetic changes and strain-dependent differences in virulence are discussed.     

Changes in immunologic response in tonsillectomized children. I. Immunosuppression in recurrent tonsillitis.

The possible immunoregulatory role of the tonsils was studied by determining immunoglobulins IgG, A, M, E and factors C'3, C'4 and PFB of the complement system before and after tonsillectomy. The synthesis in vitro of IgG and IgM by lymphocytes stimulated with pokeweed mitogen was also measured. There were statistically significant differences between pre and post-operative levels of serum IgG, IgA and IgM, which decreased after surgery. Practically no change in the mean values of IgE and no significant differences in the levels of serum C'3, C'4, and PFB, were found. The in-vitro synthesis of both immunoglobulins (IgG, IgM) by lymphocytes increased significantly after tonsillectomy. Our results suggest that not only does tonsillectomy have no counterproductive effect on the immune system, but that, on the contrary, it seems to improve the immune response, since it appears to unblock the suppression to which the immune system was subject.     

Do weekly and fast-rotating shiftwork schedules differentially affect duration and quality of sleep?

 Characteristics of shiftwork schedules can have distinct impacts on workers’ sleep. This report presents comparisons of the effects of two different shiftwork schedules on duration and quality of the main sleep episodes in comparable worker populations at two different petrochemical plants. No significant differences were found for sleep duration in comparing the two plants. However, within each plant’s shift cycles, morning and night shifts showed shorter sleep durations than all other workdays and days off. Quality of sleep was perceived as lowest for night shifts of both plant schedules, and of lesser quality for weekly than for fast-rotating shifts. These results support recommendations for reducing the number of consecutive nights of shiftwork. However, before recommending any optimal shift schedule, interactions of sleep duration and quality with shift schedules need much further evaluation. Received: 18 December 1995/Accepted: 18 July 1996     

Endothelial Vascular Function in Hypertensive Patients After Renin—Angiotensin System Blockad

It is unclear whether single and combined pharmacologic inhibition of the renin-angiotensin-aldosterone system have similar effects on endothelial function and blood pressure (BP). The authors evaluated 63 hypertensive patients divided into 4 groups (hydrochlorothiazide 25 mg/d; irbesartan [IRBE] 150 mg/d; quinapril [QUIN] 20 mg/d; or IRBE 150 mg/d + QUIN 20 mg/d) and 25 healthy normotensive subjects (normal) followed for 12 weeks. Endothelium-dependent dysfunction measured as flow-mediated dilation at Weeks 0 and 12 were: normal, 11.5%±2.4% vs 13.5%±2.0%; hydrochlorothiazide, 7.3%±2.0% vs 12.8%±3.1%; QUIN, 7.2%±2.8% vs 13.2%±2.1%; IRBE, 7.1%±2.8% vs 13.0%±2.9%; and IRBE + QUIN, 7.5%±1.9% vs 12.8%±3.0%. Nitroglycerin-mediated responses were: normal, 26.0%±1.9% vs 24.0%±2.5%; hydrochlorothiazide, 17.0%±2.2% vs 18.3%±2.6%; QUIN, 17.8%±3.2% vs 23.4%±3.0%; IRBE, 16.8%±3.6% vs 24.7%±2.0%; and IRBE + QUIN, 17.3%±3.0% vs 25.1%±2.5%. Antihypertensive therapy restored BP to normal and improved the endothelium-dependent and -independent dysfunction after renin-angiotensin-aldosterone system blockade. In a further finding, the combined effect of angiotensin-converting enzyme inhibition and angiotensin II type 1 receptor blockade was not superior to the action of either of these treatments separately.     

Rupture of the posterior tibial tendon: CT and surgical findings

Computed tomography (CT) was performed in 42 patients with 49 clinically suspected tears of the posterior tibial tendon. Twenty-eight of the 49 suspected tears were subsequently surgically explored and repaired. Three patterns of tendon abnormalities were recognized on CT scans: type I-intact, hypertrophied, heterogeneous tendon; type II-attenuated tendon; and type III-absence of a portion of a tendon. Types I and II correlated with partial rupture seen during surgery, and type III correlated with complete rupture of the tendon. CT findings were accurate in 96% of the patients who underwent surgery. In four cases (14%), tendon rupture was seen on CT scans, but the extent of the injury was underestimated and the rupture was misclassified. Reactive periostitis of the distal tibia was seen in 71% of diseased tendons and may represent an important factor in the diagnosis of tendon rupture.     

Progressive bulbar palsy: a case report diagnosed by lingual symptoms

The aim of this report is to show a case of Progressive Bulbar Palsy (PBP), diagnosed by oral medicine specialists, from oral symptoms of the disease. We have found no more than two published cases of PBP diagnosed by lingual alterations. We have followed the patient for almost four years, which is remarkable considering that the normal survival period for these patients is up to three years. We would like to emphasize the role of general dentists in the diagnosis of systemic conditions based on an oral examination that should include the oro-facial muscles.