The atypical pneumonias: The South African context

Community-acquired pneumonia (CAP) is a common clinical presentation in general practice. The prevalence and burden of disease caused by the atypical bacteria (Mycoplasma pneumoniae; Chlamydophila pneumoniae and Legionella pneumophila) are not well defined in South Africa. Each of the atypical bacteria is discussed individually with regard to clinical presentation; diagnosis and treatment. A unified approach to CAP and its management is discussed

Alkaline stress-induced apoptosis in human pulmonary artery endothelial cells.

The effect of alkaline stress, or an increase in extracellular pH (pHext), on cell viability is poorly defined. Human pulmonary artery endothelial cells (HPAEC) were subjected to alkaline stress using different methods of increasing pHext. Viability and mode of cell death following alkaline stress were determined by assessing nuclear morphology, ultrastructural features, and caspase-3 activity. Incubation of monolayers in media set to different pHext values (7.4-8.4) for 24-h induced morphological changes suggesting apoptosis (35-45% apoptotic cells) following severe alkaline stress. The magnitude of apoptosis was related to the severity of alkaline stress. These findings were confirmed with an assessment of ultrastructural changes and caspase-3 activation. While there was no difference in the intracellular calcium level ([Ca(2+)](i)) in monolayers set to pHext 7.4 versus 8.4 following the first hour of alkaline stress, blockade of calcium uptake with the chelator, EGTA, potentiated the magnitude of apoptosis under these conditions. Potentiation of apoptosis was reduced by calcium supplementation of the media. Finally, alkaline stress was associated with an increase in intracellular pH. This is the first report of apoptosis following alkaline stress in endothelial cells in the absence of other cell death stimuli.

Release of the coracoacromial ligament can lead to glenohumeral laxity: a biomechanical study.

The purpose of this study was to determine change in glenohumeral joint translation after release of the coracoacromial ligament. Six fresh, frozen unpaired glenohumeral joints were tested in a neutral position and at 30 degrees internal and 30 degrees external rotation of the humerus at 0 degrees, 30 degrees, and 60 degrees of abduction on a custom glenohumeral joint translation testing apparatus. A joint compression load of 20 N was simulated; then a 15-N load was applied to the humerus in anterior, posterior, superior, and inferior directions, and translations on the glenoid were measured with an electromagnetic tracking device. The tests were then repeated after a 1.5-cm section of the coracoacromial ligament was released from the acromion. A multivariate analysis of variance was used for statistical analyses with a P value of.05 as the level of significance. At 0 degrees and 30 degrees of abduction, release of the coracoacromial ligament resulted in a significant increase in glenohumeral joint translations, in both the anterior and inferior directions. In addition, the differences in translation between before and after the release of the coracoacromial ligament decreased in all directions as glenohumeral abduction increased, and they were not significant at 60 degrees of abduction in any of the rotations. The results of this study suggest that the coracoacromial ligament has a role in static restraint of the glenohumeral joint. It provides a suspension function and may restrain anterior and inferior translations through an interaction with the coracohumeral ligament. Although this is a biomechanical study without simulation of the shoulder muscles, it indicates that the coracoacromial ligament contributes to glenohumeral stability. Caution should be exercised in the release of the coracoacromial ligament in those with rotator cuff pain associated with glenohumeral instability.

Glenohumeral translation after arthroscopic thermal capsuloplasty with a radiofrequency probe.

The purpose of this study was to determine whether there are changes in anterior and posterior glenohumeral translation after arthroscopic thermal capsuloplasty with a radiofrequency probe. Anteriorly directed loads of 15 N and 20 N were sequentially applied to the humerus of each of 5 cadaveric glenohumeral joints, and anterior translation on the glenoid was measured through use of a customized translation apparatus and an electromagnetic tracking device. The tests were then repeated with posteriorly directed forces, and posterior translation was measured. During testing, the glenoid was rigidly fixed and the glenohumeral joint was positioned to simulate 90 degrees of shoulder abduction and 90 degrees of external rotation. By means of the radiofrequency probe, thermal energy was then applied to the anteroinferior capsuloligamentous structures; anterior and posterior translation measurements were repeated. The results showed a significant reduction in anterior and posterior translations after thermal capsuloplasty (P < .05). Anterior translation decreased from 6.8 to 4.0 mm (a 41% decrease) with the 15-N load and from 8.6 to 4.9 mm (a 42% decrease) with the 20-N load. Posterior translation decreased from 9.3 to 5.8 mm (a 36% decrease) with the 15-N load and from 10.4 to 6.5 mm (a 35% decrease) with the 20-N load. The results of this study indicate that the radiofrequency probe can be used to decrease both anterior and posterior glenohumeral translation in vitro. The biological effect on heat-treated tissues over time needs to be studied to prove that this is a satisfactory treatment for glenohumeral instability.

Synthesis and biological activity of luteinizing hormone-releasing hormone and related peptides.

Syntheses of the decapeptide luteinizing hormone-releasing hormone, less thanGlu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH2 are described. The basic properties of arginine can provide a simple repetitive isolation procedure for arginine-containing peptides. The biological activities of the decapeptide, of a range of fragments and modified fragments, and of two analogs with alteration in the series at position 4 were measured by in vitro incubation with sheep pituitary slices, measuring the liberated LH by bioassay. None of the compounds of shortened sequence were active, with the exception of less thanGlu-His-Trp which showed 1% of the decapeptide in one of four experiments. Neither [Ser(But)4]-LH-RH-nor [Leu4]-LH-RH showed significant activity indicating (despite the known activity of [Ala4]-LH-RH) the importance of this part of the structure for full biological activity.

PIP: Numerous syntheses of luteinizing homrone-releasing hormone (LH-RH), with a decapeptide structure of less than (Glu-His-Ser-Tyr-Gly-Leu-Arg-P ro-Gly-NH2, are described. Arginine offers a simple repetitive isolation procedure for arginine-containing peptides. In vitro incubation with sheep pituitary slices and measurement of liberated LH by bioassay were utilized to examine the biological activities of the de capeptide, of a range of fragments and modified fragments, and of 2 analogs with alteration in the serine at position 4. Except for less than Glu-His-Trp, which showed 1% of the activity of the decapeptide in 1 of 4 experiments, none of these compounds of shortened sequence showed activity. Despite the established activity of Ala4-LH-RH, neither Ser (But) 4-LH-RH or Leu4-LH-RH showed significant activity.