ANTEROVENTRAL WALL OF THE THIRD VENTRICLE AND DORSAL LAMINA TERMINALIS: HEADQUARTERS FOR CONTROL OF BODY FLUID HOMEOSTASIS?

1. The subfornical organ, median preoptic nucleus and the organum vasculosum of the lamina terminalis (OVLT) are a series of structures situated in the anterior wall of the third ventricle and form the lamina terminalis. The OVLT and ventral part of the median preoptic nucleus are part of a region known as the anteroventral third ventricle region.
2. Data from many laboratories, using techniques ranging from lesions, electrophysiology, neuropharmacology, Fos expression, immunohistochemistry and receptor localization, indicate that the tissue in the lamina terminalis plays a major role in many aspects of body fluid and electrolyte balance.
3. The subfornical organ and OVLT lack the blood-brain barrier and detect alterations in plasma tonicity and the concentrations of circulating hormones such as angiotensin II and possibly atrial natriuretic peptide and relaxin.
4. This information is then integrated within the lamina terminalis (probably in the median preoptic nucleus) with neural signals from other brain regions. The neural output from the lamina terminalis is distributed to a number of effector sites including the paraventricular (both parvo- and magno-cellular parts) and supraoptic nuclei and influences vasopressin secretion, water drinking, salt intake, renin secretion, renal sodium excretion and cardiovascular regulation.     

Oral rehydration solutions in gastroenteritis before and after admission to hospital

Two recent studies published in this Journal draw attention to deficiencies in treatment of children with acute infectious diarrhoea in Australia.^1,2 There is now no doubt that use of correctly constituted oral rehydration solutions provides optimal therapy for affected children unless circulation is compromised, vomiting is more than average, or complicating disorders are present. In the vast majority of cases, these complications do not occur. A high proportion of the childhood population experiences gastroenteritis at some time. It is known that 50% of Melbourne children require medical attention for rotavirus infection alone during their first 3 years of life, although less than 5% require admission.     

A theoretical consideration of some biological parameters involved in cell kinetic investigations of oral leukoplakia and abnormal states in stratified squamous epithelium

The correct interpretation of cell kinetic data for normal epithelia requires a consideration of several interrelating factors. In abnormal states, such as leukoplakia, the lack of appropriate data for these parameters makes such interpretation difficult. Consequently, an altered mitotic index need not indicate an abnormality of cell proliferation.     

The expectations of the dental graduate.

The young dental graduate expects to deliver a certain standard of health care to the community. It is likely that both the standard of care required by the Australian people and the proportion of the population seeking treatment will increase in the coming decades. The dental profession has a responsibility to meet these demands. Although dentists should expect adequate monetary return for their activities, it would be improper to limit entry into the profession solely on the grounds of seeking to maintain some present datum line of "economic viability" of practice.     

Effects of low dose oral contraceptives containing norethindrone and ethinyl estradiol on serum levels of progesterone and pituitary gonadotropins

Serum gonadotropin and progesterone levels were studied in longterm (>18 months) patients receiving oral contraceptives containing either 1.0 mg or 0.5 mg norethindrone in combination with 35 μg of ethinyl estradiol. In ten patients treated with 1.0 mg norethindrone and 35 μg ethinyl estradiol, no mid-cycle surges of LH were noted and LH levels never exceeded 225 ng/ml. FSH levels were generally elevated during the first half of the cycle. Serum progesterone concentrations in these patients and in fourteen additional women whose blood was sampled intermittently were generally less than 1 ng/ml, and no characteristic luteal phase elevation of this hormone was detected. Of six patients treated with 0.5 mg norethindrone and 35 μg ethinyl estradiol, five clearly had no mid-cycle surge of LH, and levels of this hormone never exceeded 250 ng/ml. The concentrations of FSH and progesterone in these patients and serum progesterone levels in two additional women whose blood was sampled intermittently were similar to those found in patients treated with 1 mg norethindrone and 35 μ ethinyl estradiol. In the sixth patient, hormonal levels did not follow the same pattern, but they were not characteristic of ovulation. It is concluded that there is no evidence of cyclic fluctuations in FSH, LH and progesterone characteristic of ovulation in patients treated longer than eighteen months with either 1.0 mg or 0.5 mg norethindrone in combination with 35 μg ethinyl estradiol.