Age-associated changes in neuroaxonal transport in the hypothalamo-neurohypophysial system of the mouse

In this study, we investigated age-associated changes in neuroaxonal transport of the hormone vasopressin (AVP) and its associated neurophysin (NPII), from the supraoptic nucleus (SON) of the hypothalamus to the neurohypophysis. C57BL/Icrfat male mice of 6 and 28 months of age were injected in the hypothalamus with L-[35S]cysteine. Animals were killed up to 2.25 h after injection and NPII and AVP from the SON and neurohypophysis were separated using HPLC, and the fractions counted for radioactivity. In the SON, radiolabelled NPII and AVP were first detected after 0.50 h in both young and old mice. There was no significant difference between the age-groups in the incorporation of radiolabel over the time course studied. Radiolabelled NPII in the neurohypophysis was significantly above background after 1.25 h in the young, and after 1.50 h in the old mice. The differences between the two age groups was significant (P = 0.05). Radiolabelled AVP followed a similar trend, but was not significantly above background until 1.50 h in the young and 1.75 h in the old. The differences between the two age groups was on the point of significance (P = 0.056). These results indicate a significant reduction of up to 25% in the rate of axonal transport of neurohypophyseal peptides with advancing age.

Cerebral activity prior to motion task performance: an electroencephalographic study

Cerebral activity, as reflected by power in the alpha waveband (8-13 Hz), was examined prior to the performance of three tasks with different effort and accuracy requirements. The study aimed to further investigate changes in activity observed in an earlier study in which expert karate performers exhibited significant increases in alpha band power during preparation for a training task. In contrast to the earlier research, the high effort task produced a significant decrease in 'alpha' power prior to performance. 'Alpha' power prior to the high accuracy task showed significant differences mediated by the outcome. Successful performance was preceded by higher levels of 'alpha' power than unsuccessful attempts. The reported use of a cognitive strategy on the first task produced a significant difference in activity, lower alpha power being associated with the use of such a technique.

Comments on review by Swaab--brain aging and Alzheimer's disease. "Wear and tear" versus "use it or lose it"

This review discusses a new hypothesis about cellular ageing in the context of current experimental observations and other well-known ideas, particularly "wear and tear," the relationship between metabolic rate and life span, and "free radical" reactions. However, even though these concepts are frequently used in the literature it is clear from the data discussed by Swaab that there are fundamental disagreements between the theories and experimental observations.

Stress hormone and blood glucose response following acute stroke in the elderly

We studied the relation of reactive hyperglycemia, stress hormone response, and outcome in 23 consecutive elderly patients (median age 80 [range 75-92] years) following an acute first stroke. The median delay from the onset of the stroke to the first blood sample (day 0) was 9 (range 4-22) hours. Subsequent blood samples were taken, after fasting, for the determination of blood glucose, cortisol, catecholamine, insulin, C-peptide, glucagon, and lactate concentrations on days 1, 2, 3, 7, 14, 30, and 90. For all 23 patients, a significant relation was found between the blood glucose concentration and survival (p = 0.03) and the blood glucose concentration decreased with time (p less than 0.001). There was also a significant relation between blood glucose concentration and outcome (p = 0.02). For the 15 patients with complete data, the major determinants of the blood glucose concentration were the cortisol, insulin, and glucagon concentrations (all p less than 0.001), which accounted for 42% of the variance. When all the indexes were analyzed together by logistic regression, only the cortisol concentration was related to outcome (p = 0.02). Hyperglycemia following a stroke probably reflects the intensity of the stress hormone response. We have confirmed that hyperglycemia is a predictor of outcome in persons with stroke.

The effect of endotoxin on membrane fatty acid composition in BCG-sensitized mice

The effects of endotoxin on mouse liver phospholipid fatty acid composition have been investigated. Administration of endotoxin from Salmonella abortus equi led to a decrease in the polyunsaturated fatty acid content of livers from mice sensitized with Bacille Calmette Guérin (BCG). The content of arachidonic acid fell significantly in both the phosphatidylcholine and phosphatidylinositol fractions whereas in the phosphatidylethanolamine fraction the linoleic acid content was significantly reduced. The polyunsaturated fatty acids were replaced by increased amounts of oleic acid and palmitic acid, leading to a reduction in the polyunsaturated to saturated fatty acid ratio.

Loss of resistance technique for locating the epidural space: evaluation of glass and plastic syringes

Location of the epidural space in epidural anaesthesia usually involves the measurement of loss of resistance using glass or plastic syringes. In the present study two varieties of glass syringe and one plastic type were evaluated to determine the resistive forces associated with plunger movement. The mean static (fs) and dynamic (fd) forces for polished glass syringes having a ground plunger only were fs = 0.47 X 10(-3) +/- 0.22 X 10(-3) N and fd = 0.37 X 10(-3) +/- 0.19 X 10(-3) N and for polished glass syringes having a ground barrel and plunger were fs = 0.43 X 10(-3) +/- 0.16 X 10(-3) N and fd = 0.38 X 10(-3) +/- 0.15 X 10(-3) N. Each of these values was significantly lower (P less than 0.5) than those for plastic syringes fs = 2.22 X 10(-3) +/- 0.48 X 10(-3) N and fd = 1.46 X 10(-3) +/- 0.37 X 10(-3) N. It is concluded that glass syringes are favoured over plastic for locating the epidural space because frictional forces developed with glass syringes were significantly lower than with plastic.

Haemodynamic and neurohumoral responses in elderly patients with postural hypotension

Haemodynamic and neurohumoral responses to head-up tilt were measured in 28 elderly patients with postural hypotension (EPPH) and 12 healthy elderly subjects (HE). There were no differences in catecholamines between the groups and only noradrenaline increased on tilt (P less than 0.001). Plasma renin activity and aldosterone were similar in HE and EPPH in the supine and tilt positions. In both groups vasopressin increases (P = 0.032), and plasma volume decreases were the same (P = 0.673). Supine EPPH had higher heart rates (P = 0.019) but similar cardiac indices (P = 0.621). Both had similar changes on tilting (P = 0.975 and P = 0.341). Stroke volume decrease was higher in HE (35%) than EPPH (23%; P less than 0.001). HE showed an increase in peripheral resistance on tilting with no change in EPPH (P = 0.005). EPPH had larger coefficients of variation for all variables. The differences in haemodynamic responses and the similarity of neurohumoral responses during tilting suggest end-organ failure in EPPH with individual variations. Postural hypotension in old age is not a single entity.

The ageing hypothalamo-neurohypophysial system. An analysis of the neurohypophysis in normal hydration, osmotic loading and rehydration

Age-associated changes in the structure and function of the neurohypophysis may contribute to the decreased ability to conserve water in older animals. We investigated the neurohypophyses of 6 and 28-month-old male mice using radioimmunoassay and quantitative morphological techniques. The dry-weight and volume of the neurohypophysis increased significantly with age but the quantity of vasopressin in the gland remained constant. Oxytocin levels decreased with age. A quantitative morphological analysis was performed on the compartments of the neurohypophysis from male mice of 6 and 28 months of age which were either normally hydrated, osmotically loaded, or osmotically loaded and rehydrated. The absolute volumes of the axon endings, swellings, their constituent organelles and the axon terminals containing degenerating subcellular components were determined. The design of the analysis allowed us to examine both age-related changes and statistical interactions between the age of the animal and the behaviour of a variable during the osmotic loading/rehydration phase of the experiment. There was a significant age-related reduction in the volume of the neurohypophysis occupied by the endings and swellings. The diameters of the neurosecretory granules found in the endings were significantly smaller than those in the swellings in both age groups but the size difference was greater in the young animals. Dehydration and subsequent rehydration of old male mice leads to extensive re-modelling of the neurohypophysial compartments and subcellular organelles to the configuration found in the adult animal.

Reduced survival with increasing plasma osmolality in elderly continuing-care patients

The results reported here are from a 2-year follow-up study of 58 elderly patients in a continuing-care unit. Most of these patients were in a hyperosmolar state at the time of entry (mean plasma osmolality 304 +/- 8 mOsmol/kg). The survival of those patients with the highest osmolality (greater than 308 mOsmol/kg) was significantly reduced (p = 0.025), with an increased mortality at 2 years (15/20 patients, p = 0.053). There was no correlation between age and plasma osmolality (r = 0.02) and the effect of osmolality on survival was independent of age. Hyperosmolality was either a marker for, or a cause of, increased mortality in this group of frail elderly patients.

Oxygen-dependent desulphation of monomethyl sulphate by Agrobacterium sp. M3C

Agrobacterium sp. M3C, previously isolated from canal-water for its ability to grow on monomethyl sulphate, degraded this ester with stoichiometric liberation of inorganic sulphate. In contrast with the biodegradation of monomethyl sulphate in Hyphomicrobium sp., and of other longer-chain alkyl sulphates in Pseudomonas spp., the pathway in Agrobacterium appeared not to involve a sulphatase enzyme capable of catalysing ester-bond hydrolysis. No such sulphatase was detectable under a range of conditions of bacterial culture, or using various methods for preparing cell-extracts, or different assay conditions. There was no incorporation of 18O-label from H2(18O) into the liberated inorganic sulphate. No methanol was detectable during biodegradation, and the organism was incapable of growth on methanol, and did not produce methanol dehydrogenase activity when grown on monomethyl sulphate. Tracer studies using mono[14C]-methyl sulphate indicated that formate serine and glycine were produced during the biodegradation. The presence of these amino acids, together with high activity of hydroxypyruvate reductase, indicated the operation of the serine pathway common in methylotrophs. Use of an oxygen electrode in conjunction with monomethyl[35S]sulphate showed that release of 35SO2(-4) was dependent on availability of O2, and that there was equimolar stoichiometry among monomethyl sulphate degraded, O2 consumed and 35SO2(-4) released. A proposed pathway for the degradation involved an initial mono-oxygenation to methanediol monosulphate with subsequent elimination of SO2(-4) and concomitant formation of formaldehyde. The pathway was compared with degradation mechanisms for other C1 compounds and for other sulphate esters.

Effect of lysophosphatidylcholine on the filtration coefficient in intact dog lungs

Lysophosphatidylcholine (lyso-Pc) is a lysophospholipid normally found in low concentrations in the lung. At high concentrations lyso-Pc, instilled into the airways, causes pulmonary edema. We tested the hypothesis that the edema caused by lyso-Pc was due to an increase in pulmonary microvascular membrane permeability. In 11 anesthetized dogs we continuously weighed the left lower lobes (LLL) while instilling lyso-Pc (20 mM) into the LLL airways. After 30 min we determined the microvascular membrane fluid filtration coefficient (Kf) from the relationship between the rate of LLL weight gain and the pulmonary microvascular pressure. Kf was not significantly different between the lyso-Pc-treated lobes (0.048 +/- 0.018 ml.min-1.mmHg-1) vs. control lobes (0.067 +/- 0.031 ml.min-1.mmHg-1). Our data do not support the hypothesis that lyso-Pc, instilled into the airways, causes an increase in pulmonary microvascular permeability.

Age-associated changes in the kidney of the laboratory mouse

This paper describes a qualitative and quantitative morphological investigation of the kidneys of male laboratory mice without macroscopic pathology at 6, 12, 24 and 34 months of age. In the 6- and 12-month old adults there were no signs of microscopic pathological changes in either the kidney cortex or medulla. However, at 24 and 34 months of age minor pathology, such as focal interstitial inflammation, was detected. In both these age groups there were a few glomeruli with sclerotic changes. There were no significant differences in the total volume of the kidneys, cortex, medulla or other structures with age. There was a significant increase in the diameter of the glomeruli with age but no change in the total numbers of glomeruli. The increase in volume of the glomerulus appears to be due to cellular components rather than changes in the blood vessels. It is concluded that in animals without macroscopic pathological changes there are only minor alterations in kidney structure with age, and that any alterations which do take place occur very late in the life span.

Elderly female patients in continuing care: why are they hyperosmolar?

We have shown that the majority of elderly female patients in continuing care are in a hyperosmolar state. Thirty-two out of thirty-nine subjects had an osmolality greater than 295 mosm/kg and the mean osmolality was 302 +/- 8 mosm/kg (range 280-317 mosm/kg). No significant relationship was found with the degree of confusion (rs = 0.31; p greater than 0.05). In the second part of the study neither the measured degree of hydration, or any acute, small increases in fluid input influenced the plasma osmolality.

Age-related changes in the stomach of the laboratory mouse: a quantitative morphological study

This report is of a quantitative morphological investigation of the gastric wall in the aged laboratory mouse. Male mice of 6, 9, 18, 28 and 34 months of age were killed and the mid-greater curvature of the stomach examined qualitatively and quantitatively for age-related changes. There was no evidence of superficial or atrophic gastritis in any of the mice investigated. There were significant decreases in the relative volumes of parietal and chief cell components with age, and a significant increase in other components in the lamina propria. The relative volume of the mucous cell compartment did not change with age. In all cases where a significant change was observed it took place in the 34-month-old age group when compared with 6-, 9- or 18-month-old animals. There was a progressive change in the components after 18 months of age but this only achieved significance at 34 months. It was concluded that alterations in the gastric wall take place later in the life-span and appear to be a physiological, rather than a pathological change.

A new urethral catheter

A new balloon catheter for women with a flexible urethral portion that conforms to the shape of the closed urethra was tested. In sheep control catheters caused epithelial destruction, which was absent with the conformable catheter. A 12 week crossover trial compared control catheters in 52 long stay geriatric patients. Eighty two out of 91 conformable catheters were rated as comfortable compared with 68 of 87 control (p = 0.006). The average length of time in situ was 15.9 days for the conformable catheter compared with 12.9 days for the control (p = 0.001). The average number of bypasses a week with the conformable catheter was 1.1 compared with 1.3 for the control; this difference was not significant. Examination of 249 used catheters showed significantly fewer with intraluminal obstruction with struvite among the conformable than control catheters (1 (0.8%) versus 15 (11.5%); p less than 0.001). This new catheter for women is a substantial improvement over the Foley catheter and (except in urethral stricture) is suitable for all forms of drainage.

Age changes in the human female urethra: a morphometric study

Aging in the human female urethra can contribute towards urinary problems. To our knowledge the effect of age on urethral tissues has not been quantified previously. Histological sections were prepared from 8 regions along the length of the urethra from 26 women between 19 and 88 years old. Using quantitative morphological techniques the relative volume fractions of various tissue components were determined. As age increased there was a decrease in the relative volume of striated muscle and blood vessels, and an increase in the relative volume of connective tissue. There was no change in the smooth muscle components. These age changes in the human female urethra may lead to impairment of urethral function.

Renal vasopressin receptors in ageing C57BL/Icrfat mice

The mechanism of water conservation is impaired in ageing mammals. An age-related defect in the release of vasopressin has been implicated but, more recently, attention has moved to the renal component of the water conservation mechanism. Previous studies using renal cells prepared from mice of different ages have shown that the threshold dose of vasopressin required to elicit a significant rise in cyclic AMP (cAMP) was greater in older animals. The dose-response curve was moved to the right in 35-month-old mice, i.e. the concentration of vasopressin required to give maximum cAMP output was increased. To investigate this further we examined the binding of vasopressin to renal medullary cells maintained in short-term culture, to determine whether the decreased response of cAMP levels to vasopressin is due to changes in hormone-receptor interaction. In 6-month-old male mice the dissociation constant (Kd) was 2.38 nmol/l and the maximum binding of the hormone (Bmax) was 47.6 fmol/10(6) cells, and at 30 months of age Kd was 2.37 nmol/l and Bmax was 47.0 fmol/10(6) cells. In female mice the changes were more complicated because the data for the 6-month-old mice could be split into two groups. It is concluded that there are no age-related differences in the numbers of receptors or their affinity for vasopressin, and that the decreased cAMP response is probably associated with post-receptor mechanisms in this species.

Ageing in the hypothalamo-neurohypophysial-renal system

Ageing is characterised by a failure in the maintenance of the internal environment (homeostasis) which is regulated by the hypothalamic neuroendocrine system. Of the many systems that undergo age-related degeneration is the control of water metabolism which leads to a variety of complications in the elderly. The magnocellular neurons of the hypothalamus produce the peptide anti-diuretic hormone (vasopressin) which acts on the kidney regulating water loss in the urine. This physiological axis lends itself to both fundamental studies of the cellular and molecular biology of ageing, and to studies of age-related alterations in the functional ability of elderly people. This review summarises some of the recent research into age-related changes in this system. The morphological and functional changes in the hypothalamus, neurohypophysis and kidney are described for the various species examined and the results discussed in terms of ageing in humans.

The epithelium in the female urethra: a quantitative study

Histological sections were prepared from 8 regions along the length of the urethra in 16 women 19 to 82 years old. The epithelium was examined under the light microscope at 4 points in each region and the type of epithelium was classified. Our results indicate that the human female urethra is lined by stratified squamous, pseudostratified columnar and, occasionally, transitional epithelium. There is a gradual change from squamous to columnar epithelium with advancing age. More squamous epithelium is present at the distal end of the urethra.

Long-term study of the immuno-pathological consequences of sympathetic orchiopathia in the rat

Unilateral testicular ischaemia was induced in Wistar rats by ligation and division of the testicular and deferential vessels. Damage (as assessed by a Johnsen count) to the contralateral testis caused significant spermatogenic suppression only at the equator of the testis at 28 days after operation. Cytotoxic antisperm antibody production increased progressively from 7 to 14 days and became maximal at 28 days after infarction, but after 3 and 6 months antibody production was decreasing. The presence of agglutinating antisperm antibody was noted at 28 days, 3 months and 6 months after infarction. Serum immunoglobulin estimations revealed an increase in IgG and IgM levels at 7 days and IgM levels at 14 days, supporting the contention that an immunological reaction had occurred. It is suggested that unilateral testicular ischaemia in the rat, an animal model intended to mimic torsion of the testis in the human, causes a transient immunological phenomenon (sympathetic orchiopathia) which recovers over the course of time. Caution should be exercised before regarding this relatively common surgical emergency as an aetiology of oligospermia or asthenospermia.