Pleuro-pulmonary paragonimiasis

Paragonimiasis is a food borne zoonosis due to a trematode belonging to the genus Paragonimus. Although present throughout the world, about 90% of the cases occur in Asia where around 20 million people are infected. The parasitic cycle is complex with two different intermediate hosts. Man is infected by ingesting the raw or undercooked flesh of the second host - a freshwater crab or prawn - or possibly of a paratenic mammal host (wild boar), which contains the infective larval stage metacercariae that reaches the lung which is the main target organ. Epidemiological, pathological, and clinical aspects are reviewed. The main symptoms are protracted cough, and recurrent "benign" hemoptysis. Abnormal pleuro-pulmonary imaging features are constant, but protean and non-specific, leading to frequent confusion with tuberculosis. Diagnosis is easily achieved by ova search in the sputum or pleural fluid, or by serology. Evolution is usually considered benign, although not well known. Finally, praziquantel is the effective first choice treatment. Some paradoxical aspects of this disease are underlined such as: underdiagnosis despite a very simple diagnostic procedure, or opposite tendencies according to location, either extinction or re-emergence.     

STUDIES ON INFLAMMATION : VIII. INHIBITION OF FIXATION BY UREA. A FURTHER STUDY ON THE MECHANISM OF FIXATION BY THE INFLAMMATORY REACTION

A concentrated urea solution effectively dissolves fibrin. The injection into the peritoneal cavity of a urea solution (30 or 50 per cent) together with or after an inflammatory irritant (aleuronat) prevents wholly or in part the local fixation of graphite particles or ferric chloride introduced subsequently. The histologic picture in the retrosternal lymphatics explains how this comes about. When free dissemination of graphite to the retrosternal nodes occurs, the lumen of the lymphatic vessel is unobstructed, whereas partial dissemination is accompanied by small fibrinous thrombi occluding the lumen in part only. Trypan blue injected at the periphery of an inflamed skin area treated with a concentrated urea solution and bacteria (Staph. aureus) penetrates readily into the area, whereas it fails to do so when introduced around an inflamed area consequent on the injection of distilled water and bacteria (Staph. aureus). Concentrated urea per se is an inflammatory irritant. Graphite particles injected into a peritoneal cavity previously treated with concentrated urea penetrate freely to the retrostemal lymphatic nodes; the lymphatic vessel is relatively unobstructed. Trypan blue injected into the circulating blood accumulates rapidly in cutaneous areas almost immediately after the latter have been treated with concentrations of urea ranging from 50 per cent down to 20 per cent. The results of this study furnish evidence, in addition to that already provided, that fixation of foreign substances is primarily due to mechanical obstruction caused by a fibrin network and by thrombosed lymphatics at the site of inflammation. The significance of fixation in relation to immunity and its bearing upon some of the other processes involved in the inflammatory reaction have been stressed.     

Prevalence of polymorphisms in the dihydrofolate reductase and dihydropteroate synthetase genes of Plasmodium falciparum isolates from southern Mauritania

The increasing resistance of Plasmodium falciparum in the treatment of uncomplicated malaria with pyrimethamine/sulphadoxine has been associated in several studies with the occurrence of point mutations in the genes of dihydrofolate reductase (DHFR) and dihydropteroate synthetase (DHPS). In this study, the prevalence of these mutations was examined in samples from south-east Mauritania, where atypically strong rainfalls in 1998 and 1999 led to a severe outbreak of falciparum malaria. We analysed 386 samples by polymerase chain reaction (PCR) for infection with P. falciparum, of which 162 (41.97%) were positive. These isolates were examined for point mutations in the genes of DHFR (codons 16, 51, 59, 108 and 164) and DHPS (codons 436, 437, 540, 581 and 613) by nested PCR and subsequent mutation-specific restriction enzyme digest. We found a low overall prevalence of DHFR gene mutations (up to 18.6% of isolates), but a high overall prevalence of DHPS gene mutations (up to 49.1% of isolates). Thus, emerging resistance to antifolate drugs may be expected to develop soon in the investigated area. This study demonstrates the utility of simple, relatively rapid and inexpensive molecular methods and their application in surveillance programmes. Testing for prevalence of point mutations conferring antifolate resistance might help to identify the developing of drug resistance at a very early stage.     

STUDIES ON INFLAMMATION : I. FIXATION OF VITAL DYES IN INFLAMED AREAS

Trypan blue injected into normal subcutaneous tissue passes rapidly to the regional lymphatic node and is found in lymph drawn from its efferent lymphatic. When the dye is injected into the normal peritoneal cavity it rapidly appears in the lymph of the retrosternal lymphatics and stains deeply the retrosternal lymphatic nodes. Trypan blue injected into the site of inflammation in the subcutaneous tissue or in the peritoneal cavity is fixed in the inflamed area and fails to reach the regional lymphatic nodes. If an inflammatory reaction has been produced in the dermis or in the subcutaneous tissue, trypan blue injected into the circulating blood enters the site of inflammation and is fixed so that the tissues are deeply stained.     

STUDIES ON INFLAMMATION : XIV. ISOLATION OF THE FACTOR CONCERNED WITH INCREASED CAPILLARY PERMEABILITY IN INJURY

There is present in inflammatory exudates a factor which induces a prompt increase in the permeability of normal capillaries. Its liberation and presence in exudates offers a reasonable explanation for the mechanism of increased permeability of small vessels in injured tissue. A method for the isolation and purification of this permeability factor has been described. In its essential features, this consists of treating the exudate with pyridine followed by acetone. After separation of the protein fractions further purification can be obtained by prolonged extraction with butyl alcohol or by subjecting the acetone supernatant fraction to low temperature (–20°C.). The latter favors spontaneous separation of the active principle. The purified material is a crystalline doubly refractive nitrogenous substance. The factor is evidently not a protein, yet it contains amino and carboxyl groups. It gives a positive test for the presence of an indole nucleus in its structure (Adamkiewicz test). The active material is dialyzable; and it is precipitated by concentrated ammonium sulfate. The present evidence indicates that it is an intermediary breakdown product of protein metabolism, probably belonging to the group of relatively simple polypeptides. Further studies are being conducted in an endeavor to determine its precise chemical structure.     

STUDIES ON INFLAMMATION : II. A MEASURE OF THE PERMEABILITY OF CAPILLARIES IN AN INFLAMED AREA

1. By means of a colorimetric method the concentration of trypan blue in capillaries can be estimated by direct observation and its changes followed as the dye passes out of the circulating blood stream. 2. The change in concentration of trypan blue in the capillaries of both the normal and the inflamed mesentery of frogs can be described by two separate exponential equations of the type: y = be^-ax. 3. From these equations it is found that the rate of fall of concentration following intraventricular injection of the dye is almost twice as great in the capillaries of the inflamed as in those of the normal mesentery. This difference is a measure of increased permeability with inflammation.