Modeling UV-induced inactivation of microorganisms on surfaces.

A model is presented to account for inactivation by UV light of microorganisms on the surfaces of solid materials. In the model, the surface is divided into a discrete number of zones, each having a characteristic exposure factor (alpha). This is the ratio of UV intensity actually "seen" by the microorganism to that incident on the surface. Application of the model requires inactivation data obtained under conditions where the surface microorganisms are fully exposed to incident UV (alpha = 1) as well as kinetic inactivation data for the same microorganisms actually present on the surface of interest during UV irradiation. The kinetics in question may apply either to a single species or to the characteristic microflora associated with a particular material. Standard nonlinear programming techniques were used to determine the number of zones among which the microorganisms are distributed, the alpha for each zone, and the fraction of the microbial population present in each zone. The model was applied to data previously published by Gardner and Shama for UV inactivation of Bacillus subtilis spores on the surfaces of filter papers and also to the data of Stermer et al. for UV irradiation of beef. Good representation of the kinetics was obtained, and a maximum of three zones was required to adequately represent the experimental data. One direct application of the model is that it yields quantitative information about the UV fluences necessary to achieve specified reductions in microbial viability.

Effect of a microcomputer-based registry on adult immunizations.

A survey of patients attending the Cosmopolitan International Diabetes Center showed that one third of those born prior to 1935 did not know their immunization status, and only 56% of this group remembered ever receiving tetanus vaccine. In contrast, of those born after 1935, 98% gave a history of being vaccinated for tetanus, either as a child (76%) or as an adult (22%). Eight of the 35 patients who could not remember or denied receiving pneumococcal vaccine had in fact received it. Most patients could remember whether and when they had received influenza vaccine. A microcomputer-based registry was used to generate summaries of clinical information at each patient visit. These summaries included prevention-related items. There was a three- to five-fold increase in immunization rates when the dates of the most recent vaccinations were prominently displayed on the summary at the time of each visit.

Plasma-cell granuloma producing calcitriol and hypercalcemia.

A teenage boy presented with hypercalcemia and a large intrathoracic mass. Results of an extensive evaluation, including normal findings on parathyroid hormone and urinary 3', 5'-cyclic adenosine monophosphate assays, failed to explain his hypercalcemia. During surgery, a large plasma-cell granuloma of the right middle and lower lobes was resected. Within 2 weeks, serum calcium levels returned to normal. Serum calcitriol (1,25-dihydroxyvitamin D3) levels were elevated before surgery and decreased to normal afterward, correlating with the serum calcium level. Homogenates of the plasma-cell granuloma synthesized a compound indistinguishable from calcitriol.

Elevated circulating immunoreactive calcitonin in the magnesium-deficient normocalcemic rat.

Previous studies indicate that magnesium, like calcium, stimulates the release of calcitonin (CT) from the thyroid gland. On the other hand, C-cell hyperplasia has been noted in magnesium-deficient dogs and rats. To explore further possible interrelationships between magnesium and CT, 21-day-old Sprague-Dawley male rats fed a control diet (0.043% Mg and 0.47 Ca) were match-fed with rats given either a control low calcium diet (0.043% Mg and 0.15% Ca) or a low magnesium-low calcium diet (0.001% Mg and 0.15% Ca). The low calcium content in the magnesium-deficient diet prevented the development of hypercalcemia characteristic of the magnesium-deficient rat. After 17 days, animals were killed by decapitation. Blood was obtained from some animals in the basal state and in other animals 1 min postpentagastrin or 1 min postmagnesium chloride infusion. No significant difference was found in the serum calcium level in the three groups, while the mean serum immunoreactive CT (iCT) level was significantly higher in magnesium-deficient rats both before and after pentagastrin. An acute iv infusion of MgCl2 resulted in significant increases in serum iCT in both the control and magnesium-deficient animals. The results of this study demonstrate that basal serum iCT levels and their response to pentagastrin are increased in magnesium-deficient, normocalcemic animals. The further increase in serum iCT after magnesium infusion in magnesium-depleted animals appears paradoxical and indicates that the relationship between extracellular magnesium and iCT release is not a simple feedback mechanism. It is possible that the increase in circulating iCT may be a response to extracellular-intracellular differences in magnesium concentration. Alternatively, the increased C-cell activity may be secondary to some unknown metabolic alteration induced by magnesium deficiency, rather than to magnesium deficiency per se.

Intrathoracic and multiple abdominal pheochromocytomas in von Hippel-Lindau disease.

A patient had von Hippel-Lindau disease, a functional intrathoracic paraganglioma (pheochromocytoma), bilateral adrenal pheochromocytomas, and a para-adrenal pheochromocytoma. Seven other members of the patient's family had features of von Hippel-Lindau disease and one, a cousin, had medullary carcinoma of the thyroid. This is the first report of a pheochromocytoma arising outside the abdomen in von Hippel-Lindau disease and the 25th report of intrathoracic pheochromocytoma in the literature. The association between von Hippel-Lindau disease and pheochromocytoma is reviewed.

Optic nerve hypoplasia associated with absent septum pellucidum and hypopituitarism.

Five children had bilateral optic nerve hypoplasia, absent septum pellucidum, and hypopituitarism. Absence of the septum pellucidum was shown by computed axial tomography. All of the children were first-born. One of the children was definitely not mentally retarded and one at age 7 months was developing normally. All of the children had severe visual impairment and nystagmus. Pupillary responses varied. Ocular deviations included one with exotropia and three with esotropia. The extent of pituitary hormone deficiency varied. One child was symptomatic from birth, having severe hypoglycemia and seizures. Two children had prolonged neonatal jaundice. One unusual case had growth hormone deficiency with a normal growth curve. Another child with diabetes insipidus had dehydration and polyuria without polydipsia.