General anesthesia for cesarean section in a Singapore maternity hospital: a retrospective survey.

We conducted a retrospective study of all cases of cesarean section at the KK Women's and Children's Hospital over a one-year period from September 1, 2002 to August 31, 2003, with the aim of evaluating current anesthetic practice. These cases were identified using hospital databases and relevant data was extracted from clinical notes. There were 14244 deliveries during the study period with a cesarean section rate of 25.2% (3583 cases). Of these, 20.4% (732 cases) were performed under general anesthesia. Maternal request was the chief reason for general anesthesia, especially among elective cases. Regional block failure accounted for 16% of the general anesthesia cases performed or 4.0% of the total regional techniques attempted. Regional block failure rate was highest for emergency cases in which an indwelling labor epidural catheter was used to provide surgical anesthesia via a bolus top-up. General anesthesia still has a definite place for cesarean delivery despite the predominant use of regional techniques in our institution.

Free-floating cryostat sections for immunoelectron microscopy: Bridging the gap from light to electron microscopy.

Frozen skin sections are routinely used for light microscopic immunohistochemical study of the skin basement membrane zone for two reasons: some skin basement membrane zone proteins are labile to routine chemical fixation, and skin is not amenable to vibratome sectioning. However, inherent limitations of conventional frozen sections, including compromised morphology and a requirement for glass slide-mounting, usually limit immunohistochemical study to the light microscopy level. In the present study, we introduce use of unfixed, free-floating cryostat sections for characterization of immunolocalizations of selected skin basement membrane proteins at both the light and electron microscopy level. The new procedure employs free-floating cryostat sections that can be processed as routine tissue specimens and can be subjected to a variety of special staining procedures including immunohistochemistry. Especially useful is the ease of progressive processing of the same tissue specimen from light microscopy to electron microscopy. In this regard, the method renders itself useful when results of immunolabeling experiments need to be elucidated quickly at histological and ultrastructural levels as required for diagnostic and accelerated investigative strategies.

Microwave superheating enhances immunocytochemistry in the freshly frozen rat brain.

The goal of this study was to evaluate the effects of microwave irradiation on immunocytochemical staining in freshly frozen rat brain tissue using an antibody previously shown to successfully stain only formalin-fixed materials. GFAP immunoreactivity was markedly increased in sections exposed to microwave heating when compared with control tissue. Uniform staining enhancement was mainly a result of increased numbers of immunoreactive soma and large astrocytic processes. The integrity of the tissue was not affected by this treatment. Other antibodies need to be tested with this method, but our results suggest that microwave irradiation is useful for rapid antigen retrieval in freshly frozen central nervous system tissue.

Microdensitometric measures of cytoplasmic RNA and total protein in pyramidal neurons of the insular cortex and midfrontal gyrus in patients with Alzheimer's disease.

Scanning and integrating microdensitometry of azure B- and Coomassie brilliant blue G-stained tissue sections was used to measure the levels of RNA and protein, respectively, in pyramidal neurons of the insular cortex (INS) and midfrontal gyrus (MFG) in patients with Alzheimer's disease (AD) and age-matched, nondemented control subjects. AD was associated with a decreased neuronal RNA (by 7.4 per cent) and protein (by 28.7 per cent) content in INS. Although the neuronal RNA content was maintained at the control amounts in MFG, the average protein level was lower (14.7 per cent) in AD patients. These results demonstrate a disease-related impairment in metabolic function in two brain regions connected via discrete corticocortical pathways. Such findings support the hypothesis that a primary site of pathology occurs in AD, and specific neural deficits occur secondarily in certain connected brain regions.

Cytophotometric analysis of T-2 toxin induced alterations in chromatin condensation and neuronal nuclear volume of rat supraoptic-magnocellular neurons.

Quantitative cytophotometry and ocular filar micrometry were used to monitor T-2 toxin induced alterations in chromatin and neuronal nuclear volume in supraoptic-magnocellular neurons of rat hypo-thalami. Thirty male Sprague-Dawley rats (200-220g) were given a single i.p. injection of T-2 toxin (0.5, 0.75, 1.0 and 1.5 X LD50), a trichothecene mycotoxin; rats were decapitated 8 hours post-dosing. After stoichiometric Feulgen-DNA staining of brain sections, scanning-integrating microdensitometry was used to quantify changes in the susceptibility of chromatin to Feulgen acid hydrolysis. Changes in neuronal nuclear volumes were also determined histometrically. Within the magnocellular neurons of the supraoptic nuclei, significant reductions in F-DNA reactivity were observed in the 0.5, 0.75, and 1.0 X LD50 groups (i.e. 3.7%, 4.4% and 2.5%, respectively); however, rats receiving 1.5 X LD50 T-2 toxin showed no difference in F-DNA reactivity compared to controls. In addition, ocular filar micrometry demonstrated increased neuronal nuclear volumes in all groups receiving T-2 toxin, and following an inverse trend to that seen with F-DNA stainability. Additional observations included pronounced polydipsia, polyphagia and horripilation in the experimental groups, independent of the dosages employed; these changes were evident within 1 hour post-injection. It is postulated that the T-2 toxin induced reduction in the susceptibility of chromatin to Feulgen acid hydrolysis and concomitant increases in neuronal nuclear volumes represent an early indication of impaired metabolic activity. Since these neurons are important sites of vasopressin (antidiuretic hormone) synthesis, these data suggest an impaired osmoregulatory ability. The pronounced polydipsia which occurred shortly after intoxication is further evidence of this impairment. Although these findings do not provide insight relating to the mechanism of osmoregulatory disruption, it is evident that an impaired ability to osmoregulate is among the earliest indications of acute T-2 toxin mycotoxicosis.