Regulation of ACTH secretory pathways in cultured pituitary cells

Although chloroquine, an agent that disrupts regulated protein secretion, has previously been shown to decrease the adrenocorticotropic hormone (ACTH) secretory response to adenosine 3',5'-cyclic monophosphate or corticotropin-releasing factor (CRF) in AtT-20 and rat anterior pituitary cells, respectively, it has no effect on the response to vasopressin. The present study extended experiments with chloroquine to cultured sheep anterior pituitary cells, which have a greater maximum response to vasopressin. Chloroquine (200 microM) had no effect on basal ACTH secretion or on stimulation by vasopressin. In contrast to the rat, the net response to CRF was tripled by chloroquine in ovine cells. The effect of chloroquine on the response to CRF was more effective by coexposure of cells to CRF and chloroquine than by pretreatment with chloroquine. Monensin or vinblastine did not increase the ACTH response to CRF. The results indicate ACTH release in response to vasopressin is chloroquine insensitive in this way, can be dissociated from the mechanism that responds to CRF, and would be consistent with the CRF response mechanism involving pathways that can alter the secretory pool of ACTH. When chloroquine acts to increase the response to CRF, it is likely not to act by stabilizing the CRF-receptor complex.

Cognitive functioning in late Lyme borreliosis

Lyme borreliosis, a tick-borne multisystem disease, may cause a variety of neurologic complications, including meningoencephalitis and encephalopathy. To evaluate neurobehavioral function following treated Lyme borreliosis, 15 patients with Lyme disease and complaints of persistent cognitive difficulty a mean of 6.7 months following antibiotic treatment underwent neuropsychological evaluation and were compared with 10 healthy controls, matched in aggregate for age and education, who underwent the identical neuropsychological assessment. Compared with controls, patients with Lyme disease exhibited marked impairment on memory tests and particularly on selective reminding measures of memory retrieval. The memory impairment did not correlate with serum or cerebrospinal fluid anti-Borrelia burgdorferi antibody titers and was not explained by magnetic resonance imaging findings or depression. The cause of this encephalopathy is currently unknown; however, indirect effects of systemic infection or other toxic-metabolic factors may be partly responsible.

Somatic recombination rather than uniparental disomy suggested as another mechanism by which genetic imprinting may play a role in the etiology of Prader-Willi syndrome

Six Prader-Willi syndrome (PWS) patients with normal karyotypes and their parents were analyzed to determine the nature of the molecular aberrations present in the proximal region of 15q and to determine the parental origin of the aberrant chromosome 15. In addition, the likelihood that uniparental disomy plays a significant role in the etiology of PWS patients with normal karyotypes was studied. Restriction fragment length polymorphisms (RFLPs) recognized by seven probes [pML34 (D15S9), pTD3-21, pCGS0.9, pCGS1.1 (D15S10), IR4.3 (D15S11), IR10.1 (DS15S12), p189-1 (D15S13), IR39 (D15S18), and CMW-1 (D15S24)] mapping to the Prader-Willi chromosome region (PWCR) and an additional two probes [pMS1-14 (D15S1); the cDNA of neuromedin B] mapping elsewhere on chromosome 15 were analyzed in the six PWS patients and their parents. Copy number of each locus within the PWCR was determined by densitometry. Molecular rearrangements of the proximal region of 15q were observed in all of the six probands and the origin of the aberrant chromosome 15 when determined was consistently paternal in origin. While data obtained from our six patients does not support the mechanism of disomy, results obtained from three of the six patients show more complex rearrangements hypothesized to have resulted from somatic recombination. These rearrangements have resulted in acquired homozygosity and the lack of a paternal allele at various loci within the PWCR. The presence of only a maternal contribution at certain loci as the result of somatic recombination may be another mechanism by which genetic imprinting plays a role in the presentation of the PWS phenotype.

ICI 181,037: a novel eukalemic diuretic with antiarrhythmic activity

ICI 181,037, the most active compound from a series of 1,1-diarylcarbin-1-ol-2 amines, was evaluated for diuretic and cardiovascular activity. In saline-loaded rats, the magnitude of water diuresis and saluresis produced by ICI 181,037 (10 mg/kg, p.o.) was equal to that of hydrochlorothiazide. Water diuresis and saluresis produced by ICI 181,037 were enhanced with SKF 525A, ampicillin or neomycin plus lincomycin, suggesting that ICI 181,037 is an active diuretic. In conscious dogs, the saluretic activity of ICI d-181,037 (5 mg/kg, p.o.) was about 80% of the corresponding hydrochlorothiazide value, whereas the l-isomer demonstrated only minimum saluretic activity. In both rats and dogs, the concurrent kaliuresis after ICI 181,037 or its enantiomers was minimal as compared to hydrochlorothiazide. Following chronic dosing with diuretic doses, the basal levels of plasma potassium in dogs were not altered. In amphibian in vitro models for mimicking mammalian nephron, ICI 181,037 and its enantiomers demonstrated antinatriferic and antichloriferic activities, suggesting multiple renal sites of action for this agent. Racemic ICI 181,037 and its isomers reversed ouabain-induced arrhythmia in dogs and/or reduced the ouabain-induced mortality in mice after intravenous administration. It is concluded that ICI 181,037, particularly its d-isomer, is a novel eukalemic diuretic and possesses antiarrhythmic activity.

Transport across the nuclear envelope: enigmas and explanations

The transport of molecules across the nuclear envelope plays a central role in the metabolism of the cell. Significant advances in three major areas highlight the limits of our current knowledge and point to the prospect of exciting future developments. Firstly, findings that ions and small proteins do not diffuse freely into the nucleus call into question the current views of nuclear envelope permeability. Secondly, indications that nuclear protein import can be regulated in conjunction with the cell cycle and development have been confirmed by the clear demonstration of regulated nuclear entry of specific transcription factors and morphogens. Thirdly, identification and characterisation of candidate receptor proteins indicates that the recognition of the nuclear targeting sequence occurs in the cytoplasm, suggesting that a different recognition event occurs at the nuclear pore.

Lead and minor hearing impairment

We examined data recorded for 3,545 subjects aged 6-19 y who participated in the Hispanic Health and Nutrition Survey. We sought to confirm a relationship between blood lead levels and elevated hearing thresholds that we previously reported in a similar study in which data from the Second National Health and Nutrition Examination Survey was used. Lead was associated with an increased risk of hearing thresholds that were elevated above the standard reference level at all four frequencies (i.e., 500 Hz, 1,000 Hz, 2,000 Hz, and 4,000 Hz). Lead was also associated with hearing thresholds when they were treated as a continuous outcome. The relationships appeared to continue at blood lead levels less than 10 micrograms/dl. An increase in blood lead, from 6 micrograms/dl to 18 micrograms/dl, was associated with a 2-dB loss in hearing at all frequencies, and an additional 15% of children had hearing thresholds that were below the standard at 2,000 Hz.

Vmw65 phosphorothioate oligonucleotides inhibit HSV KOS replication and Vmw65 protein synthesis

Phosphorothioate-modified oligomers have been shown to be more stable than natural oligomers to serum and cellular nucleases. For this reason we used these analogs to explore the utility of antisense molecules as potential antiviral agents. The oligomers we studied are complementary to the initiation region of the Vmw65 (alpha-TIF) gene of HSV-1 which is important both for its structural role and in the transactivation of the alpha genes of HSV. Our results demonstrate that Vmw65-specific oligomers inhibit HSV KOS replication in a dose-dependent manner from 25 micrograms/ml (4.3 microM) to 50 ng/ml (9 nM). Vmw65 protein synthesis is inhibited from 51 to 68% at 5 micrograms/ml (0.8 microM) using Vmw65-specific oligomers 293s and 432s respectively. A random AT-rich oligomer, 007s, inhibited HSV KOS replication in a non-dose-dependent manner. Inhibition was only observed at a concentration of 12.5 micrograms/ml (2.1 microM) or more, using an MOI (multiplicity of infection) of 0.05 PFU/cell and a 24-h post-infection harvest.

Growth hormone alters lipolysis and hormone-sensitive lipase activity in 3T3-F442A adipocytes

While growth hormone (GH) has long been known as a lipolytic hormone, it has been difficult to study the cellular mechanisms for this effect. Since cultured 3T3-F442A adipocytes have recently proven to be useful to study chronic effects of GH on adipocyte metabolism, we examined the effects of GH on lipolysis. In these cells, GH alone produced a dose-dependent increase in the release of glycerol after 24 to 48 hours. The maximum increase occurred with 10 ng/mL human GH. The effect of GH was similar in the presence and absence of dexamethasone. Under each condition, the stimulation of glycerol release was accompanied by a GH-induced increase in the activity of hormone-sensitive lipase (HSL), a key lipolytic enzyme. The increase in HSL required 24 hours with GH and lasted at least 48 hours. The increase in HSL activity by epinephrine, like glycerol release, was potentiated by GH. Although GH potently simulates the activity of the lipogenic enzyme glycerol phosphate dehydrogenase (GPD) in differentiating 3T3-F442A preadipocytes, GH had a negligible effect on GPD activity in the differentiated adipocytes with chronic or short-term incubation. However, in contrast to the chronic effect of GH, short-term (30-minute) incubation with GH inhibited epinephrine-stimulated glycerol release, a characteristic transient antilipolytic effect of GH. These studies indicate that chronic GH treatment is lipolytic in cultured 3T3-F442A adipocytes, and document that lipolytic responses to GH involve an increase in the activity of HSL.

Cell-free expression of the coxsackievirus 3C protease using the translational initiation signal of an insect virus RNA and its characterization

We have expressed the 3C protease of coxsackievirus B3 (CVB3) in a cell-free system. This expression system employs the translational initiation signal of an insect virus RNA, black beetle virus (BBV) RNA 1, to direct CVB3-specific protein synthesis. Using this expression system, we demonstrate that a biologically active 3C protease is synthesized which possesses both cis and trans processing capabilities. This in vitro-synthesized 3C protease is analogous to the native 3C, which was obtained from cytoplasmic extracts of CVB3-infected HeLa cells, in all biological parameters that were evaluated. In addition, antibody prepared against the 3C protease purified from extracts of CVB3-infected HeLa cells cross-reacts with the 3C protease produced in this cell-free system. Using the translational initiation signal from BBV RNA 1, we also have expressed the CVB3 capsid precursor and part of the P2 region in vitro, and have shown that the capsid precursor is cleaved between 1C (VP3) and 1D (VP1) by the proteolytic activity of in vitro-synthesized 3C in trans. Evidence also is presented to implicate the 2A protein of CVB3 as having proteolytic function.

A potent new synthetic analog of vasopressin with relative agonist specificity for the pituitary

The biological activity of a new synthetic analog of vasopressin, deamino[D-3-(3'-pyridyl)-Ala2, Arg8] vasopressin, was assessed in a number of assays. Antidiuretic (V2) and vasoconstrictor (V1), agonist and antagonist activities were assessed in rats in vivo. Corticotropin-releasing activity was assessed with cultured dissociated ovine anterior pituitary cells in vitro and in sheep in vivo. Compared to vasopressin, the analog is a weak agonist at antidiuretic receptors (1/381 compared to AVP); it is a weak antagonist of the vasoconstrictor response (pA2 = 6.22). Nonetheless, the analog is a full, relatively potent agonist at pituitary corticotrope receptors (relative potency of 1/36). These data indicate that analogs of vasopressin can be synthesized which are relatively selective for agonist activity at pituitary vasopressin receptors, and in doing so, further support the contention that the pituitary receptor is quite distinct from the classical V1 receptor.

Vasculitic skin ulcers associated with myelofibrosis--a case report

This is the case report of a seventy-seven-year-old woman with ulcerated skin vasculitis of the lower extremities that preceded the appearance of myelofibrosis. No previous report of this association has been found in a survey of the literature.

Short stature and decreased serum growth hormone-binding protein in the Mountain Ok people of Papua New Guinea

Two circulating GH-binding proteins (GH-BP), one of which is related to the GH receptor, have been described. To assess their possible role in or link with determining statural growth, we measured their activity/level in the serum of 25 adult subjects from a short-statured population from the highlands of Papua New Guinea (Mountain Ok people, similar in stature to African pygmies) and in 25 normal-statured North American control subjects. The Mountain Ok people have normal levels of GH, insulin-like growth factor-I (IGF-I), IGF-II, and serum albumin and prealbumin in association with short stature, making them a unique study population. Levels of the high affinity (GH receptor-related) GH-BP were significantly lower in the Mountain Ok subjects than in the taller controls (5.2 +/- 3.0% vs. 10.6 +/- 3.9% GH bound/160 microL, respectively; mean +/- SD; P less than 0.001). In contrast, the low affinity GH-BP was comparable in Mountain Ok and control subjects. Because of the structural similarity between the GH receptor and GH-BP, these data suggest that a limitation in GH receptor/GH-BP endowment may be associated with short stature despite normal circulating IGF-I levels. Alternatively, it is possible that the GH-BP itself plays an important role in growth promotion. Thus, the GH receptor (and/or GH-BP) complement may be a determinant of the genetically programmed height achieved.

Effect of AVP on susceptibility of ovine pituitary cells to a cytotoxic analogue of CRF

Although exposure to arginine vasopressin (AVP) has been reported to induce anterior pituitary corticotrophs to bind and become responsive to corticotropin-releasing factor (CRF), the identity of these inducible CRF target cells is unknown. Such cells may themselves be the AVP-responsive corticotrophs or other cells that become CRF targets secondary to a paracrine signal from AVP target cells. The present study used a cytotoxin (Cx), specific for CRF target cells, that eliminates responses of treated cells to a subsequent challenge with CRF but leaves responses to AVP intact. We hypothesized that, if AVP target corticotrophs themselves become CRF targets, then the addition of AVP during treatment with Cx should render these cells susceptible to the cytotoxin and should eliminate the response to subsequent AVP as well. Ovine pituitary cells were chosen for the study because they respond more robustly than rat cells to AVP. Pretreatment of ovine pituitary cells with Cx (400 pM) or Cx plus AVP (10 nM) eliminated the adrenocorticotropic hormone (ACTH) secretory response to CRF (10 nM), as assessed 3 days later. Cx alone also reduced the secretory response to AVP from 23.9 +/- 3.4 to 11.5 +/- 1.9 ng ACTH/3 h (P less than 0.05). However, pretreatment with AVP (10 nM) plus Cx caused no further reduction in the secretory response to AVP (10.1 +/- 2.6 ng ACTH/3 h). These data suggest that, if AVP induces erstwhile non-CRF target cells to become CRF targets, then these induced cells are not themselves initially AVP target corticotrophs.

Effects of V2 receptor activity on the pressor response to vasopressin in the rat

1. To determine the contribution of V1 and V2 receptor activity on the enhancement of reflex buffering of the pressor response to arginine-vasopressin (AVP), mean arterial pressure (MAP) and heart rate (HR) changes were examined in response to graded injections of phenylephrine, AVP, or Phe2Orn8OT, a potent, selective V1-receptor agonist in the absence and presence of Val4DArg8VP, a potent, selective V2-receptor agonist. 2. There were no significant differences in MAP responses to the V1 agonist in the absence and presence of the V2 agonist in either conscious intact or autonomic-blocked rats. 3. Autonomic blockade with methscopolamine and hexamethonium increased the pressor sensitivity to phenylephrine threefold. In contrast, the pressor sensitivities to AVP and Phe2Orn8OT were increased 14-fold and 11-fold, respectively, by autonomic blockade. 4. V2-receptor activity does not have any inherent vasocative action or synergistic vasoactive action with V1-receptor activity. 5. V2 receptors do not play a role in enhancing reflex buffering of the pressor response to AVP; V1 receptors are suggested to play the role.

Pulmonary function and ambient particulate matter: epidemiological evidence from NHANES I

The relationship between pulmonary function and quarterly average levels of total suspended particulates (TSP) was examined for adults who resided in 49 of the locations where the First National Health and Nutrition Examination Survey (NHANES I) was conducted. Statistically significant relationships were observed between TSP levels and forced vital capacity (FVC) and forced expiratory volume at one second (FEV1.0). These relationships remained strong across several specifications and sample changes, e.g., exclusion of cities with two highest and two lowest TSP levels, restriction of sample to whites only. Anthropometric measurements and socioeconomic characteristics of the subjects were included in the analysis, and we restricted the sample to "never" smokers. The results indicate a 1 standard deviation increase (about 34 micrograms/m3) in TSP from the sample mean of 87 micrograms/m3 was associated with an average decrease in FVC of 2.25%. The results of this analysis also suggest that there is a threshold level (i.e., approximately 60 micrograms/m3 [quarterly average]) of TSP below which a relationship with pulmonary function ceases to exist.

Comorbidity of psychiatric disorders and personality profiles of American World War II prisoners of war

To characterize the effects of trauma sustained more than 40 years ago, prevalence of psychiatric disorders and personality dimensions were examined in a sample of 62 former World War II POWs. The negative effects of their experiences are reflected in their multiple lifetime diagnoses and in their current personality profiles. Fifty percent met DSM-III posttraumatic stress disorder (PTSD) criteria within 1 year of release; 18 (29%) continued to meet the criteria 40 years later at examination (chronic PTSD). A lifetime diagnosis of generalized anxiety disorder was found for over half the entire sample; in 42% of those who never had PTSD, 38% of those with recovery from PTSD, and 94% of those with chronic PTSD. Ten percent of those without a PTSD diagnosis had experienced a depressive disorder, as had 23% of those with recovery from PTSD and 61% of the POWs with chronic PTSD. The combination of depressive and anxiety disorders also was frequent in the total sample (61%). Current MMPIs of three groups with psychiatric diagnosis were compared with those of POWs who had no diagnoses and with a group of Minnesota normal men. Profile elevations for the groups, from highest to lowest, were: POWs with chronic PTSD, POWs with recovery from PTSD, POWs with other psychiatric diagnoses, POWs with no disorders, and Minnesota normal men. Symptoms of anxiety, depression, and somatic concerns combined with the personality styles of suppression and denial characterize the current adjustment of negatively affected POWs.

Lead, blood pressure, and cardiovascular disease in men and women

Lead has been shown to be associated with elevated blood pressure in males in the NHANES II survey and in numerous other studies. This study confirms the association in males aged 20 to 74 and documents a significant, although weaker, association in females as well. Prospective cardiovascular disease studies such as the Framingham study indicate that increases in blood pressure should be associated with increased risk of cardiovascular disease. Using electrocardiogram data from NHANES II, this study confirms the expected association of lead with left ventricular hypertrophy (p less than 0.01). Such an association with permanent cardiovascular changes adds weight to the blood pressure findings. The logistic risk coefficients from the Framingham study can be combined with the study's association between lead and blood pressure to examine its implication for more serious outcomes. The results suggest that a halving of the population mean blood lead level would reduce myocardial infarctions by approximately 24,000 events per year and incidence of all cardiovascular disease by over 100,000. These numbers suggest a small attributable risk compared to the vast incidence of cardiovascular disease in the U.S., but a large attributable risk compared to most environmental toxins. Several biological mechanisms have been identified, with different implications for the use of bone lead as an exposure measure.

Lead, blood pressure, and cardiovascular disease in men and women

Lead has been shown to be associated with elevated blood pressure in males in the NHANES II survey and in numerous other studies. This study confirms the association in males aged 20 to 74 and documents a significant, although weaker, association in females as well. Prospective cardiovascular disease studies such as the Framingham study indicate that increases in blood pressure should be associated with increased risk of cardiovascular disease. Using electrocardiogram data from NHANES II, this study confirms the expected association of lead with left ventricular hypertrophy (p less than 0.01). Such an association with permanent cardiovascular changes adds weight to the blood pressure findings. The logistic risk coefficients from the Framingham study can be combined with the study's association between lead and blood pressure to examine its implication for more serious outcomes. The results suggest that a halving of the population mean blood lead level would reduce myocardial infarctions by approximately 24,000 events per year and incidence of all cardiovascular disease by over 100,000. These numbers suggest a small attributable risk compared to the vast incidence of cardiovascular disease in the U.S., but a large attributable risk compared to most environmental toxins. Several biological mechanisms have been identified, with different implications for the use of bone lead as an exposure measure.

The Marfan syndrome locus: confirmation of assignment to chromosome 15 and identification of tightly linked markers at 15q15-q21.3

The Marfan syndrome is a common autosomal dominant disorder of connective tissue. Despite many years of intensive investigation, the primary genetic defect has not yet been identified. Reverse genetic methods, targeted at mapping this disease gene, have resulted in an initial report of linkage of the genetic locus for the Marfan phenotype in Finnish families to two polymorphic markers on chromosome 15. We have investigated four large multiplex American families with classic Marfan syndrome using standard genetic linkage methods. Our data confirm the assignment of the Marfan syndrome gene to chromosome 15, but establish a more centromeric location (defined by markers D15S25 and D15S1) as the most probable site for the genetic defect (lod score = 12.1, theta = 0.00). These data should facilitate identification and characterization of the Marfan syndrome gene and, in selected families, have immediate application to diagnosis of equivocal cases or prenatal counseling.

Candida albicans pacemaker site infection

A 69-year-old man with a history of diabetes and episodic lymphocytopenia underwent pacemaker implantation for complete heart block. Despite prophylactic antibiotics, pocket irrigation, and strict sterile technique, a fungal (Candida albicans) pacemaker site infection developed that required pacemaker explanation and systemic amphotericin B therapy. After 3 days of temporary pacing, a second pulse generator was implanted on the opposite side. At 2-year follow-up, he has had no recurrence of pacemaker infection. This report underscores the predilection of diabetics for infections, and in particular, their susceptibility to Candida albicans.

Daily diaries of respiratory symptoms and air pollution: methodological issues and results

Daily diaries of respiratory symptoms are a powerful technique for detecting acute effects of air pollution exposure. While conceptually simple, these diary studies can be difficult to analyze. The daily symptom rates are highly correlated, even after adjustment for covariates, and this lack of independence must be considered in the analysis. Possible approaches include the use of incidence instead of prevalence rates and autoregressive models. Heterogeneity among subjects also induces dependencies in the data. These can be addressed by stratification and by two-stage models such as those developed by Korn and Whittemore. These approaches have been applied to two data sets: a cohort of school children participating in the Harvard Six Cities Study and a cohort of student nurses in Los Angeles. Both data sets provide evidence of autocorrelation and heterogeneity. Controlling for autocorrelation corrects the precision estimates, and because diary data are usually positively autocorrelated, this leads to larger variance estimates. Controlling for heterogeneity among subjects appears to increase the effect sizes for air pollution exposure. Preliminary results indicate associations between sulfur dioxide and cough incidence in children and between nitrogen dioxide and phlegm incidence in student nurses.

Bicaudate ratio as a measure of caudate volume on MR images

Many studies have used ratios based on intercaudate distance as a measure of caudate atrophy and ratios based on bifrontal distance as a measure of ventricular enlargement independent of caudate atrophy. The purpose of the current study was to determine to what extent these ratios correlate with caudate area and volume and frontal horn area in various groups of patients. The three linear ratio measures, obtained from MR scans, were bicaudate ratio, bifrontal ratio, and bifrontal distance divided by bicaudate distance. Area and volume measures were corrected for brain size. Subjects included patients with autism, obsessive-compulsive disorder, and Huntington disease, as well as normal controls. As expected, the patients with Huntington disease had the largest bicaudate ratio, bifrontal ratio, and frontal horn area. Both bicaudate ratio and bifrontal ratio were fairly good measures of frontal horn size for most groups. Consistent with theoretical expectations, the bifrontal ratio was not highly correlated with caudate area or volume ratios. Bicaudate ratio and bifrontal distance/bicaudate distance were correlated with caudate volume for the patients with Huntington disease, but not for any of the other groups. Bifrontal distance/bicaudate distance was the best single predictor of caudate volume for all groups combined. It is concluded that bicaudate ratio and bifrontal distance/bicaudate distance are fairly good measures of caudate atrophy, but are poor measures of caudate size when no atrophy is present.

Differential regulation of two glucose transporters by chronic growth hormone treatment of cultured 3T3-F442A adipose cells

New methods for the analysis of glucose transporters were used to analyze the molecular mechanisms involved in the insulin-antagonistic effects of growth hormone (GH), which is known as a diabetogenic hormone. The ability of GH to alter the number and mRNA levels of two different glucose transporters in cultured 3T3-F442A adipocytes was investigated using specific antibodies and cDNA probes. At concentrations of GH as low as 0.5 and 5 ng/ml and at incubation times as short as 4 h, GH decreased rates of 2-deoxyglucose uptake in 3T3-F442A adipocytes. 3-O-Methyl-D-glucose uptake was inhibited to an extent similar to that of 2-deoxyglucose uptake (60-80%) after a 24-h incubation with GH (500 ng/ml), indicating that GH inhibits glucose metabolism specifically at the step of glucose transport. To determine whether reduced rates of glucose transport might result from reduced numbers of glucose transporters, whole cell lysates were prepared from GH-treated cells and subjected to immunoblotting using antibodies that identify Glut 1 (HepG2/rat brain) and Glut 4 (muscle/adipose) transporters. GH caused a time- and dose-dependent decrease in the number of Glut 1 transporters in the cell. Northern and slot-blot analyses showed a GH-induced dose-dependent decrease in levels of Glut 1 mRNA. In contrast, levels of Glut 4 transporter and mRNA were unchanged by GH. These data suggest that GH regulates Glut 1 and Glut 4 transporters differentially and that it exerts its inhibitory effect on glucose uptake at least in part by decreasing the synthesis of Glut 1 transporters. These studies provide the first evidence that GH regulates a key gene in metabolic regulation and can interfere with gene expression.

Serum-beta-N-acetyl hexosaminidase (beta-NAH) in the elderly

Serum levels of beta-N-Acetyl Hexosaminidase (beta-NAH) provide information on the normal non-phagocytic function of Kupffer cells in the liver. Beta-NAH can thus be used as an indicator for non-parenchymal non-phagocytic liver cell function, whereas most of the more routine liver function tests measure hepatocytic status or function. Serum beta-NAH activity levels found in 49 patients and 10 healthy individuals above the age of 65 did not differ significantly from those found in younger controls. The results clearly indicate that beta-NAH serum activity in the aged is within normal limits and, if accepted as a routine measure of the non-phagocytic function of non-parenchymal liver cells, could be used in all adults.