Histopathology in tropical medicine: a perspective

Histopathology may serve a wide spectrum of diagnostic purposes in tropical medicine other than for infectious and parasitic diseases. In addition, it is essential in defining new pathological entities and collecting statistical data on morbidity and mortality. It should also constitute a basic support for advancement and research in tropical diseases. For practical purposes, both histopathology and cytopathology are often more effective than clinical chemistry and microbiology in providing the clinician with a final diagnosis. They do not rely on complicated and delicate equipment, and the few reagents they require can be stored indefinitely. Formalin fixation permits most histological methods to be used, including special stains and immunohistochemistry. Formalin-fixed material can be examined several days after excision. Implementing pathology laboratories in tropical countries may constitute a practical, cost-effective approach to the planning of diagnostic services at the regional or district level. A fraction of the medical graduates in developing countries should be devoted to the staffing of these laboratories.     

Carotid surgery in stroke prevention

Extracranial carotid disease accounts for up to 50 percent of strokes. Transient ischemic attacks are associated with a 30 to 35 percent risk of stroke within five years of the initial episode. Carotid endarterectomy is a safe and effective way of reducing the risk of stroke in patients with TIAs. It is also helpful in patients with amaurosis fugax, and may benefit selected patients with acute stroke or those with asymptomatic but hemodynamically significant stenosis.     

Further evidence of preserved memory function in Alzheimer's disease

Memory performance of elderly patients in the early stages of Alzheimer's disease (DAT) was compared with that of elderly control subjects. In explicit tests of recognition memory, which involve conscious recollection, the DAT patients were grossly impaired. In implicit tests of anagram solution and wordstem completion, which do not require conscious recollection, the DAT patients were not impaired. These findings further support the idea that a separate memory system, episodic memory, underlies conscious recollection, that it is this system which is most commonly damaged in amnesia, and that memory systems not involving conscious recollection may be spared in the early stages of Alzheimer's disease.     

Astroglial alterations in rat hippocampus during chronic lead exposure.

The present study was performed in order to follow the response of astroglial cells in the rat hippocampus to chronic low-level lead exposure. The experiments combined immunohistochemistry using anti-glial fibrillary acidic protein (GFAP) antibody and conventional transmission electron microscopy (EM). Chronic administration with drinking water [1 g% w/v (subclinical dose) of lead acetate dissolved in distilled water] was started through the mother's milk when pups were 7 days old. Following weaning, experimental offspring were treated for 3 months with the same concentration of adulterated water. The group of intoxicated animals and their controls were sacrificed by perfusion-fixation at 30, 60, and 90 days of exposure. After 60 days of lead treatment, staining of GFAP-positive cells demonstrated an astroglial transformation from the quiescent to the reactive state, characterized by an increase in GFAP. In control rats no changes in GFAP immunostaining were observed. The intensity of the astroglial response was enhanced after 90 days of lead intoxication, showing an increment of GFAP immunoreactivity. Quantification of these changes was made by computerized image analysis, confirming that the sectional areas of the astroglia in lead-exposed animals were larger than those in controls. These results are consistent with the ultrastructural alterations. Simultaneously with the increment in gliofilaments, intranuclear inclusions were seen in some astrocytes. The mechanisms by which lead affects astrocytes are unknown. Probably the astroglial changes induced by lead intoxication produce microenvironmental modifications that may disturb the neuronal function.     

Infantile spasms in COFS syndrome

Cerebro-oculo-facial-skeletal (COFS) syndrome is a rare, autosomal recessive syndrome characterized by microcephaly, microphthalmia and/or cataracts, neurogenic arthrogryposis, and multiple congenital anomalies. A term female infant with COFS syndrome who developed infantile spasms at the age of 3 months is reported. The patient had a good response to intramuscular ACTH with disappearance of infantile spasms and resolution of the hypsarrhythmic pattern on electroencephalography succeeded by a slow, synchronous pattern. Modified hypsarrhythmia returned after ACTH therapy was discontinued. Infantile spasms have not previously been reported in association with COFS syndrome and are a potentially treatable aspect of the disease. This patient may add to the clinical spectrum of COFS syndrome or may have a variant.     

Reconstruction of the mandible using the scapular spine pedicled upon trapezius muscle; description of the posterior approach to the transverse cervical vessels

We describe the reconstruction of the mandible using the spine of the scapula pedicled upon trapezius in a woman who had undergone previous mandibular irradiation and surgery. We show how the vascular supply to the trapezius scapular spine compound flap can be approached posteriorly and the spine of the scapula used to provide good length and contour for replacement of a wide mandibular defect.     

Prevention of diabetes in BioBreeding/Worcester rats with monoclonal antibodies that recognize T lymphocytes or natural killer cells

Diabetes-prone BioBreeding/Worcester (BB/Wor) rats received thrice weekly injections of mAb against antigens expressed on the surface of all T cells (OX19), cytotoxic/suppressor, and NK cells (OX8), helper/inducer cells (W3/25, OX35, OX38), and Ia+ cells (OX6, 3JP, OX17). Treatment with OX8 or OX19 achieved stable reductions of splenic and peripheral blood NK cells and helper/inducer T lymphocytes, respectively, and protected against diabetes. OX19 injections also prevented lymphocytic insulitis, thyroiditis, and the synthesis of autoantibodies to thyroid colloid and smooth muscle antigens. OX8 injections reduced splenic NK-mediated YAC-1 cell lysis, but did not prevent insulitis, thyroiditis, or autoantibody synthesis. Injections of mAb specific for antigens on the surface of helper/inducer cells, and for cells expressing IaE antigens provided marginal protection against diabetes without reductions of phenotypic subsets. These findings suggest that pancreatic beta cell destruction in the spontaneously diabetic BB/Wor rat is mediated by the combined action of NK and helper/inducer cells.     

Neuronal development of the chick cerebral cortex. A Golgi study

The neuronal morphological development of the avian telencephalic cortex (DMC) is studied in Golgi-stained brain sections. The neuronal types at embryonic days 10, 13, 16, as well as of newborn chick are identified. The immature neurons are characterized by the presence of hair-like processes, growth cones and dendritic varicosities. These characteristics are absent in neuronal types of newborn chick. There are five patterns of differentiation, which produce six neuronal types in the newborn chick: horizontal neurons, pyramidal neurons, bipyramidal neurons, short axon multipolar neurons, long axon multipolar neurons and periventricular neurons. The morphological features of migrating embryonic cells are described. The dendritic spines appear in 16-day embryos in the majority of neuronal types.