Targeting local tissues by transdermal application: Understanding drug physicochemical properties that best exploit protein binding and blood flow effects

The targeting of topically applied drug molecules into tissues below a site of application requires an understanding of the complex interrelationships between the drug, its formulation, the barrier properties of the skin, and the physiological processes occurring below the skin that are responsible for drug clearance from the site, tissue, and/or systemic distribution and eventual elimination. There is still a certain amount of controversy over the ability of topically applied drugs to penetrate into deeper tissues by diffusion or whether this occurs by redistribution in the systemic circulation. The major focus of our work in this area has been in determining how changes in drug structure and physicochemical properties, such as protein binding and lipophilicity, affect drug clearance into the local dermal microcirculation and lymphatics, as well as subsequent distribution into deeper tissues below an application site. The present study outlines our recent thinking on the drug molecule optimal physical attributes, in terms of plasma and tissue partitioning behaviour, that offer the greatest potential for deep tissue targeting. Drug Dev. Res. 46:309-315, 1999. (C) 1999 Wiley-Liss, Inc.

Administration of growth hormone or IGF-I to pregnant rats on a reduced diet throughout pregnancy does not prevent fetal intrauterine growth retardation and elevated blood pressure in adult offspring

Increasing evidence from human epidemiological studies suggests that poor growth before birth is associated with postnatal growth retardation and the development of cardiovascular disease in adulthood. We have shown previously that nutritional deprivation in the pregnant rat leads to intrauterine growth retardation (IUGR), postnatal growth failure, changes in the endocrine parameters of the somatotrophic axis, and to increased blood pressure in later life. In the present study, we investigated whether administration of insulin-like growth factor-I (IGF-I) or bovine growth hormone (GH) during pregnancy could prevent IUGR and/or alter long-term outcome. Dams h-om day 1 of pregnancy throughout gestation received a diet of nd libitum available food or a restricted dietary intake of 30% of ad libitum fed dams. From day 10 of gestation, dams were treated for 10 days with three times daily subcutaneous injections of saline (100 mu l), IGF-I (2 mu g/g body weight) or GH (2 mu g/g body weight). Maternal weight gain was significantly increased (P

Substrate-dependent regulation of human arylamine N-acetyltransferase-1 in cultured cells

Arylamine N-acetyltransferase-1 (NAT1) is a polymorphically expressed enzyme that is widely distributed throughout the body. In the present study, we provide evidence for substrate-dependent regulation of this enzyme. Human peripheral blood mononuclear cells cultured in medium supplemented with p-aminobenzoic acid (PABA; 6 mu M) for 24 h showed a significant decrease (50-80%) in NAT1 activity. The loss of activity was concentration-dependent (EC50 similar to 2 mu M) and selective because PABA had no effect on the activity of constitutively expressed lactate dehydrogenase or aspartate aminotransferase. PABA also induced down-regulation of NAT1 activity in several human cell lines grown at confluence. Substrate-dependent downregulation was not restricted to PABA. Addition of other NAT1 substrates, such as p-aminosalicylic acid, ethyl-p-aminobenzoate, or p-aminophenol to peripheral blood mononuclear cells in culture also resulted in significant (P < .05) decreases in NAT1 activity. However, addition of the NAT2-selective substrates sulfamethazine, dapsone, or procainamide did not alter NAT1 activity. Western blot analysis using a NAT1-specific antibody showed that the loss of NAT1 activity was associated with a parallel reduction in the amount of NAT1 protein (r(2) = 0.95). Arylamines that did not decrease NAT1 activity did not alter NAT1 protein levels. Semiquantitative reverse transcriptase polymerase chain reaction of mRNA isolated from treated and untreated cells revealed no effect of PABA on NAT1 mRNA levels. We conclude that NAT1 can be down-regulated by arylamines that are themselves NAT1 substrates. Because NAT1 is involved in the detoxification/activation of various drugs and carcinogens, substrate-dependent regulation may have important consequences with regard to drug toxicity and cancer risk.

Clinical measures of obesity and weight loss in men

OBJECTIVES: (?) To determine the relationship between waist circumference and body weight in overweight men both before and after participation in a weight loss program; and (2) to make recommendations for the appropriate use of these measures at various stages of weight toss. DESIGN: Weight and waist circumference measures were taken in two diverse groups of men both before and 1-2y after commencing a men's 'waist loss' program. Regression analyses were used to assess the relationship between weight and waist measures. SUBJECTS: One group of 42 retired Caucasian men from New South Wales, and one group of 45 indigenous men from the Torres Strait region of Northern Australia. RESULTS: There were differences in the relationships of weight and waist circumference before the program and change in weight and change in waist circumference after weight loss. These differences were similar in both groups of men (indigenous men and retired Caucasian men), with a 1 cm waist loss being on average equivalent to about 3/4 kg, but with wide variability, suggesting inter-individual variation in fat losses from different depots. This variation suggests that neither weight nor waist alone is a sufficient measure of fat loss for men. CONCLUSIONS: Weight and waist circumference should both be used at various stages in the clinical situation to assess change in body fat in men involved in obesity reduction.

The Australian Burden of Disease Study: measuring the loss of health from diseases, injuries and risk factors

This is an overview of the first burden of disease and injury studies carried out in Australia. Methods developed for the World Bank and World Health Organization Global Burden of Disease Study were adapted and applied to Australian population health data. Depression was found to be the top-ranking cause of non-fatal disease burden in Australia, causing 8% of the total years lost due to disability in 1996. Mental disorders overall were responsible for nearly 30% of the non-fatal disease burden. The leading causes of total disease burden (disability-adjusted life years [DALYs]) were ischaemic heart disease and stroke, together causing nearly 18% of the total disease burden. Depression was the fourth leading cause of disease burden, accounting for 3.7% of the total burden. Of the 10 major risk factors to which the disease burden can be attributed, tobacco smoking causes an estimated 10% of the total disease burden in Australia, followed by physical inactivity (7%).

Neurons in the hilus region of the rat hippocampus are depleted in number by exposure to alcohol during early postnatal life

We have previously shown that exposing rats to a relatively high dose of ethanol during early postnatal life resulted in a deficit in spatial learning ability. This ability is controlled, at least in part, by the hippocampal formation. The purpose of the present study was to determine whether exposure of rats to ethanol during early postnatal life affected the number of specific neurons in the hippocampus. Wistar rats were exposed to a relatively high daily dose of ethanol between postnatal days 10 and 15 by placing them for 3 h each day in a chamber containing ethanol vapor. The blood ethanol concentration was about 430 mg/dl at the end of the exposure period. Groups of ethanol-treated (ET) rats, separation controls (SC), and mother-reared controls (MRC) were anesthetized and killed at 16 days of age by perfusion with phosphate-buffered glutaraldehyde (2.5%). The Cavalieri principle was used to determine the volume of various subdivisions of the hippocampal formation (CA1, CA2+CA3, hilus, and granule cell layer), and the physical disector method was used to estimate the numerical densities of neurons within each subdivision. The total number of neurons was calculated by multiplying estimates of the numerical density with the volume. There were, on average, about 441,000 granule cells in the granule cell layer and 153,000 to 177,000 pyramidal cells in both the CA1 and CA2+CA3 regions in all three treatment groups. In the hilus region, ET rats had about 27,000 neuronal cells. This was significantly fewer than the average of 38,000 such neurons estimated to be present in both MRC and SC animals. Thus, neurons in the hilus region may be particularly vulnerable to the effects of a high dose of ethanol exposure during early postnatal life. (C) 2000 Wiley-Liss, Inc.

An outbreak of blood disease of banana in Irian Jaya, Indonesia

Blood disease of banana is substantiated by using the polymerase chain reaction for the first time from Irian Jaya, Indonesia.

Blood vessels from bone marrow

Lengths of silastic tubing were inserted into the peritoneal cavity of rats or rabbits. By two weeks the free-floating implants had become covered by a capsule consisting of several layers of macrophage-derived myofibroblasts and collagen matrix overlaid by a single layer of mesothelial cells. The tubing was removed from the harvested implant and the tissue everted. This now resembled an artery with an inner lining of mesothelial cells (the intima), a media of myofibroblasts, and an outer collagenous adventitia. The tube of living tissue was grafted by end-to-end anastomoses into the transected carotid artery or abdominal aorta of the same animal in which the tissue had been grown, where it remained parent for four months and developed structures resembling elastic lamellae, The myofibroblasts developed a high volume fraction of myofilaments and became responsive to contractile and relaxing agents similar to smooth muscle cells of the adjacent artery wall.

Loss of connectivity in Alzheimer's disease: an evaluation of white matter tract integrity with colour coded MR diffusion tensor imaging

A novel MRI method-diffusion tensor imaging-was used to compare the integrity of several white matter fibre tracts in patients with probable Alzheimer's disease. Relative to normal controls, patients with probable Alzheimer's disease showed a highly significant reduction in the integrity of the association white matter fibre tracts, such as the splenium of the corpus callosum, superior longitudinal fasciculus, and cingulum. By contrast, pyramidal tract integrity seemed unchanged. This novel finding is consistent with the clinical presentation of probable Alzheimer's disease, in which global cognitive decline is a more prominent feature than motor disturbance.

A new blood-fluke, Cardicola Forsteri, (Digenea : Sanguinicolidae) of southern blue-fin tuna (Thunnus Maccoyii) in aquaculture

Cardicola forsteri sp. nov. (Digenea: Sanguinicolidae) is described from the heart of captive southern blue-fin tuna, Thunnus maccoyii (Scombridae), from South Australia. The new species is distinguished from other species of Cardicola by its very extensive testis, the length of its oesophagus, the length of its gut caeca and the form of its ovary. Cardicola smithi appears to be associated with heart and gill lesions(1).

Sporadic and familial pheochromocytomas are associated with loss of at least two discrete intervals on chromosome 1p

Pheochromocytomas are tumors of the adrenal medulla originating in the chromaffin cells derived from the neural crest. Ten % of these tumors are associated with the familial cancer syndromes multiple endocrine neoplasia type 2, von Hippel-Lindau disease (VHL), and rarely, neurofibromatosis type 1, in which germ-line mutations have been identified in RET, VHL, and NF1, respectively. In both the sporadic and familial forms of pheochromocytoma, allelic loss at 1p, 3p, 17p, and 22q has been reported, yet the molecular pathogenesis of these tumors is largely unknown. Allelic loss at chromosome 1p has also been reported in other endocrine tumors, such as medullary thyroid cancer and tumors of the parathyroid gland, as well as in tumors of neural crest origin including neuroblastoma and malignant melanoma, In this study, we performed fine structure mapping of deletions at chromosome 1p in familial and sporadic pheochromocytomas to identify discrete regions likely housing tumor suppressor genes involved in the development of these tumors. Ten microsatellite markers spanning a region of similar to 70 cM (Ipter to 1p34.3) were used to screen 20 pheochromocytomas from 19 unrelated patients for loss of heterozygosity (LOH). LOH was detected at five or more loci in 8 of 13 (61%)sporadic samples and at five or more loci in four of five (80%) tumor samples from patients with multiple endocrine neoplasia type 2. No LOH at 1p was detected in pheochromocytomas from two VHL patients, Analysis of the combined sporadic and familial tumor data suggested three possible regions of common somatic loss, designated as PCI (D1S243 to D1S244), PC2 (D1S228 to D1S507), and PC3 (D1S507 toward the centromere). We propose that chromosome Ip may be the site of at least three putative tumor suppressor loci involved in the tumorigenesis of pheochromocytomas. At least one of these loci, PC2 spanning an interval of <3.8 cM, is Likely to have a broader role in the development of endocrine malignancies.

Allelic loss of cyclophilin 40, an estrogen receptor-associated immunophilin, in breast carcinomas

Purpose: Cyclophilin 40 (CyP40) is an estrogen receptor-associated protein which appears to modify receptor function. The aim of this study was to determine the extent of allelic loss at the CyP40 locus in a panel of breast carcinomas using a newly characterized microsatellite marker located upstream of the CyP40 gene and then to correlate this with losses at chromosomal sites for cancer-associated genes. Methods: Allelic loss at CyP40 was determined from patients' matched tumor and normal breast tissue using Genescan 672 software analysis of fluorescently labeled, PAGE-separated PCR products incorporating the marker. For each patient, allelic loss at CyP40 was then assessed and compared with losses at markers for various cancer-associated genes. Results: Allelic loss was detected in 30% of breast carcinomas from patients heterozygous for the CyP40 marker. All carcinomas demonstrating allelic loss were grade II or III invasive ductal carcinomas and generally showed multiple losses at other sites near known cancer-associated genes. Conclusions: The polymorphic marker which we characterized was useful in determining allelic loss at the CyP40 locus in breast cancer patients and when applied in these studies in conjunction with various cancer-associated gene markers, suggests that deletions in the region of the CyP40 gene might be a late event in breast tumor progression.

Systemic administration of antisense p75(NTR) oligodeoxynucleotides rescues axotomised spinal motor neurons

The 75 kD low-affinity neurotrophin receptor (p75(NTR)) is expressed in developing and axotomised spinal motor neurons. There is now convincing evidence that p75NTR can, under some circumstances, become cytotoxic and promote neuronal cell death. We report here that a single application of antisense p75(NTR) oligodeoxynucleotides to the proximal nerve stumps of neonatal rats significantly reduces the loss of axotomised motor neurons compared to controls treated with nonsense oligodeoxynucleotides or phosphate-buffered saline. Our investigations also show that daily systemic intraperitoneal injections of antisense p75(NTR) oligodeoxynucleotides for 14 days significantly reduce the loss of axotomised motor neurons compared to controls. Furthermore, we found that systemic delivery over a similar period continues to be effective following axotomy when intraperitoneal injections were 1) administered after a delay of 24 hr, 2) limited to the first 7 days, or 3) administered every third day. In addition, p75(NTR) protein levels were reduced in spinal motor neurons following treatment with antisense p75(NTR) oligodeoxynucleotides. There were also no obvious side effects associated with antisense p75(NTR) oligodeoxynucleotide treatments as determined by behavioural observations and postnatal weight gain. Our findings indicate that antisense-based strategies could be a novel approach for the prevention of motor neuron degeneration associated with injuries or disease. (C) 2001 Wiley-Liss, Inc.

Recombinant human growth hormone, but not insulin-like growth factor-I, enhances central fat loss in postmenopausal women undergoing a diet and exercise program

We examined the effect of recombinant human growth hormone (rhGH) and/or recombinant human insulin-like growth factor-I (rhIGF-I) on regional fat loss in postmenopausal women undergoing a weight loss regimen of diet plus exercise. Twenty-seven women aged 59-79 years, 20-40% above ideal body weight, completed a 12-week program consisting of resistance training 2 days/week and walking 3 days/week, while consuming a diet that was 500 kcal/day less than that required for weight maintenance, Participants were randomly assigned in a double-blind fashion to receive rhGH (0.025 mg/kg BW/day: n=7), rhIGF-I (0.015 mg/kg BW/day: n=7), rhGH + rhIGF-I (n = 6), or placebo (PL: n = 7). Regional and whole body fat mass were determined by dual X-ray absorptiometry. Body fat distribution was assessed by the ratios of trunk fat-to-limb fat (TrF/LimbF) and trunk fat-to-total fat (TrF/TotF), Limb and trunk fat decreased in all groups (p < 0.01). For both ratios of fat distribution, the rhGH treated group experienced an enhanced loss of truncal compared to peripheral fat (p less than or equal to 0.01), with no significant change for those administered rhIGF-I or FL. There was no association between change in fat distribution and indices of cardiovascular disease risk as determined by serum lipid/lipoprotein levels and maximal aerobic capacity. These results suggest that administration of rhGH facilitates a decrease in central compared to peripheral fat in older women undertaking a weight loss program that combines exercise and moderate caloric restriction, although no beneficial effects are conferred to lipid/lipoprotein profiles, Further, the effect of rhGH is not enhanced by combining rhCH with rhIGF-I administration. In addition, rhIGF-I does not augment the loss of trunk fat when administered alone.