Effects of iron and culture filtrates on killing of Neisseria gonorrhoeae by normal human serum.

Neisseria gonorrhoeae GC9, both colony types T2 and T4, were killed by normal human serum, although populations of colony type T4 were more susceptible. Ferric ammonium citrate prevented the killing of populations of both T2 and T4 colony types. Other iron compounds tested showed no protective effect, nor did ammonium citrate or the divalent cations magnesium or calcium. A filtrate from cultures of an N. gonorrhoeae strain grown in a liquid defined medium showed a similar protective effect in the serum assay. The filtrate appeared to chelate iron, as measured by decreased ability of iron-free transferin to bind iron in the presence of the filtrate. However, the two effects did not appear to be related. Neither ferric ammonium citrate nor the culture filtrate sufficiently inactivated complement to account for protection.     

Radiographic studies of the ventricles in syringomyelia

Summary Radiographic investigations of 171 patients with communicating syringomyelia have been reviewed. Hydrocephalus was found in onethird of the cases and has occasionally progressed after operation on the posterior fossa, sometimes with accompanying clinical deterioration. The outlets of the fourth ventricle were usually abnormal; tonsillar descent, arachnoiditis and both together were seen. Arachnoiditis correlated strongly with a history of difficult birth. The foramen of Magendie was sometimes patent and sometimes blocked. There was no consistent level of occlusion corresponding to a persistent roof of the fourth ventricle. The cisterna magna was usually small or obliterated but some examples of large cisterns or subarachnoid pouches were found. Radiological demonstration of a communication from the fourth ventricle to the syrinx occurred in only seven patients by positive contrast material and not by air. It is suggested that a sizable communication is rare at the time when patients seek treatment.     

Planning and decision making for ambulatory surgery

There has been rapid growth in the number of ambulatory surgical centers in the United States over the past few years. Yet little research has been done to assist community health planners and surgeons in decision making and planning for ambulatory surgery. In this paper, an analytical framework is developed to assist surgeons in deciding whether to perform a procedure on an ambulatory or an inpatient basis. The Hospital Discharge Survey data collected by the National Center for Health Statistics are also analyzed to investigate their applicability in this analytical framework as well as to aid planners in developing community-wide ambulatory surgery projections. In spite of the limitations on the available data, the models developed here suggest possible future avenues for planning ambulatory surgeries.     

Where is group practice headed?

A CRAHCA educational program was held recently to determine the changes in the health service environment that are most likely to occur in the near future, and how these changes will affect medical group practice.     

The epidemiology of Entamoeba histolytica in Mexico City. A pilot survey I

Stocks of intestinal amoebae isolated from hospital patients in Mexico City and grown in monoxenic culture were compared among themselves and with those already described (Sargeaunt & Williams, 1979), using the electrophoretic patterns of four enzymes: glucose phosphate isomerase (GPI), phosphoglucomutase (PGM), L-malate:NADP⁺ oxido-reductase (oxalacetate-decarboxylating) (ME) and hexokinase (HK). New isoenzyme groups (Sargeaunt & Williams, 1979) of all the amoebae, including Entamoeba histolytica have been demonstrated. Amongst these have been found seven more groups of E. histolytica, two new groups of E. hartmanni, one new group of Dientamoeba fragilis and one new group of E. coli. Of the seven new groups of E. histolytica three are known to originate from patients with clinical amoebiasis whilst the remainder are from asymptomatic subjects. Only 11·2% of the 125 isolations were associated with clinical amoebiasis, and these are clearly distinguished from the isolations from asymptomatic patients by their electrophoretic isoenzyme pattern.     

Observations on the human cornea in vitro

Human corneas seem to have a vegetative physiology similar to the rabbits. The swelling-hydration characteristics of the stromas are similar and there is a pump in the endothelium which continuously pumps fluid out of the stroma. An electrical potential is found across the endothelium which is stimulated and stabilised in the presence of 0·5 mm reduced glutathione. Both fluid flow across the endothelium and trans-endothelial electrical potential are reversibly abolished in the absence of exogenous bicarbonate and CO₂ which suggests that the two phenomena are manifestations of a common underlying mechanism.Difficulties in using the specular microscope on human cornea in vitro are illustrated. It is suggested that results from such experiments usually cannot be interpreted.