Unilateral eye enucleation in adult rats causes neuronal loss in the contralateral superior colliculus

Several studies have reported the morphological changes induced by unilateral enucleation during early neonatal life on the developing visual system. This study has examined cellular changes in the superior colliculi by removal of a single eye in adult rats. Anaesthetised male hooded rats aged 90 d had their right eyes removed. Groups of nonenucleated control and enucleated rats were killed when aged either 150 or 390 d. The brains were removed and both the right and left superior colliculi dissected out. The volume of the stratum griseum superficiale (SGS) within these colliculi was estimated stereologically by light microscopy, as well as the numerical density and total number of neurons within this cell layer. The volume of the cell layer was reduced by about 40% on the side contralateral to the enucleated eye but not on the ipsilateral side at both survival periods examined. The numerical density of neurons within the SGS was unaffected by the enucleation so that the colliculi contralateral to the enucleated eye showed a substantial loss of neurons within this cells layer. This study demonstrates the importance of the retinal ganglion cell input, even in adult animals, for maintaining the viability of neurons in the SGS layer of the superior colliculus.

Interactions between imidazoline compounds and sulphonylureas in the regulation of insulin secretion

1. Imidazoline alpha 2-antagonist drugs such as efaroxan have been shown to increase the insulin secretory response to sulphonylureas from rat pancreatic B-cells. We have investigated whether this reflects binding to an islet imidazoline receptor or whether alpha 2-adrenoceptor antagonism is involved. 2. Administration of (+/-)-efaroxan or glibenclamide to Wistar rats was associated with a transient increase in plasma insulin. When both drugs were administered together, the resultant increase in insulin levels was much greater than that obtained with either drug alone. 3. Use of the resolved enantiomers of efaroxan revealed that the ability of the compound to enhance the insulin secretory response to glibenclamide resided only in the alpha 2-selective-(+)-enantiomer; the imidazoline receptor-selective-(-)-enantiomer was ineffective. 4. In vitro, (+)-efaroxan increased the insulin secretory response to glibenclamide in rat freshly isolated and cultured islets of Langerhans, whereas (-)-efaroxan was inactive. By contrast, (+)-efaroxan did not potentiate glucose-induced insulin secretion but (-)-efaroxan induced a marked increase in insulin secretion from islets incubated in the presence of 6 mM glucose. 5. Incubation of rat islets under conditions designed to minimize the extent of alpha 2-adrenoceptor signalling (by receptor blockade with phenoxybenzamine; receptor down-regulation or treatment with pertussis toxin) abolished the capacity of (+)- and (+/-)-efaroxan to enhance the insulin secretory response to glibenclamide. However, these manoeuvres did not alter the ability of (+/-)-efaroxan to potentiate glucose-induced insulin secretion. 6. The results indicate that the enantiomers of efaroxan exert differential effects on insulin secretion which may result from binding to effector sites having opposite stereoselectivity. Binding of (-)-efaroxan (presumably to imidazoline receptors) results in potentiation of glucose-induced insulin secretion, whereas interaction of (+)-efaroxan with a second site leads to selective enhancement of sulphonylurea-induced insulin release.

Probing contacts to the DNA backbone in the trp repressor-operator sequence-specific protein-nucleic acid complex using diastereomeric methylphosphonate analogues

Fourteen analogue DNA sequences containing the trp operator sequence and a single diastereomeric methylphosphonate linkage are each prepared from the stereochemically pure nucleoside methylphosphonate dimer building block, prepared as a phosphoramidite. The analogue sequences are shown to be single diastereomers on the basis of HPLC analysis of the digestion mixture; in each case, only a single diastereomeric dimer is present. These analogue sequences can be used effectively to probe for interactions to either of the prochiral phosphate oxygens as illustrated by their use to identify critical interactions in the trp repressor-operator complex. In a number of cases, the pairs of diastereomeric analogue sequences exhibit variable binding affinities that can be used to identify one of the prochiral phosphate oxygens as a critical site for complex-stabilizing interactions. Upon the basis of dissociation constants, apparent incremental binding energies are assigned to specific interactions. In all but one example, these identified sites for interactions to the phosphate backbone can be correlated with contacts implicated by the crystal structure analysis of the trp repressor-operator complex.

Detection of APGWamide-like immunoreactivity in the sea scallop, Placopecten magellanicus

In pulmonate gastropods, the peptide, Ala-Pro-Gly-Trp-NH2 (APGWamide), appears to be located nearly exclusively in the neural circuitry controlling the male reproductive organs. This neuropeptide and related neuropeptides are also present and apparently bioactive in bivalve molluscs, although their physiological role in these latter animals is unknown. The present report uses immunohistochemistry to examine the distribution of APGWamide and/or related peptides within the tissues of the deep sea scallop, Placopecten magellanicus. Much of the APGWamide-like immunoreactivity (APGWa-LIR) was detected in the central nervous system (CNS) of both juvenile and adult scallops, where it was concentrated in the cerebral, pedal and parietovisceral ganglia, particularly in the cortex of ganglionic cells and their axons which extend into the central neuropilar region. APGWa-LIR was also detected in the nerves ramifying from these ganglia. In addition, strong APGWa-LIR was localized in what appeared to be axonal terminals within peripheral tissues including the striated adductor muscle, foot, gills, labial palps, lips, tentacles and gonads of the juvenile scallops. The presence of APGWa-LIR was also confirmed in the gonads of adults of both sexes. Cursory examinations of the CNS of the mussel, Mytilus edulis, and the oyster, Crassostrea virginica, revealed the presence of APGWa-LIR in cell bodies and processes in these bivalve species as well. It is concluded that APGWamide and/or related peptides are probably important neurotransmitters and/or neuromodulators of several central and peripheral functions in P. magellanicus and other bivalves. Future work must focus on the possible roles for APGWamide in the physiological processes of these and other bivalve species.

Exposure of tilapian fish to the pesticide lindane results in hypocellularity of the primary hematopoietic organ (pronephros) and the spleen without altering activity of phagocytic cells in these organs

Tilapia were dosed by intraperitoneal injection for 5 consecutive days with either 20 or 40 mg/kg of the environmental contaminant hexachlorocyclohexane (lindane). The effects of this organochlorine pesticide on morphology and total cellularity of the spleen and pronephros were examined on the second day following termination of dosing. The functional capacity of phagocytic cells isolated from both spleen and pronephros was also evaluated as possible additional indicators of chemical-induced immunotoxicity. A dose-related reduction was found in spleen and pronephros total white blood cell counts in the fish exposed to lindane. In addition, hypocellularity of lymphoid regions in the spleen and pronephros was evident in chemical-exposed animals upon histopathological examination. However, phagocytosis of fluorescent microspheres by phagocytic cells isolated from the spleen and pronephros was not inhibited by the exposure to lindane. Similarly, no decrease in phorbolmyristate acetate (PMA)-stimulated hydrogen peroxide production was observed in phagocytic cells collected from lindane-exposed fish. These results suggest that cellular depletion in tilapia spleen and pronephros may represent a more sensitive indicator of lindane exposure than does the functional capacity of phagocytic cells isolated from these hematopoietic organs. Ultrastructural observations support this hypothesis and, further, suggest that lymphocytic cells may be targeted at the present exposure levels.

Plasma leptin concentrations and OB gene expression in subcutaneous adipose tissue are not regulated acutely by physiological hyperinsulinaemia in lean and obese humans

OBJECTIVES

To determine the effects of obesity on fasting plasma leptin levels and assess the effects of feeding on plasma leptin and OB gene expression in subcutaneous adipose tissue in non-diabetic subjects.

DESIGN

Blood and subcutaneous adipose tissue needle biopsy samples were obtained after an overnight fast and 1, 2 and 3 h following a mixed meal (606 kcal).

SUBJECTS

Eighteen female subjects: eight lean with a mean age of 40.1 yr (range 20-65) and mean body mass index of 22.24 kg/m2 (range 18.6-26.6) and ten obese subjects with a mean age of 48.6 yr (range 29-71) and body mass index of 33.53 kg/m2 (range 28.7-41.7).

RESULTS

Apart from obesity the only significant difference between groups was a 2.6 fold higher fasting plasma leptin concentration in obese subjects compared to leans (26.9 +/- 2.9 vs 10.2 +/- 2.22 (P < 0.05) respectively). Adipose tissue OB mRNA levels were not significantly higher in the obese group. Plasma leptin correlated with BMI and visceral fat weight in lean subjects only. No significant association between plasma leptin and adiposity was evident in obese patients. In addition, there was no association between plasma leptin and the insulin: glucose ratio (an index of insulin sensitivity). Following a mixed meal, post-prandial plasma insulin levels were significantly increased, with a concomitant significant reduction in plasma NEFA levels in both groups. Despite the large increase in plasma insulin, there were no post-prandial changes in either plasma leptin concentrations or subcutaneous adipose tissue OB mRNA levels in either lean or obese subjects.

CONCLUSIONS

The data indicate that plasma leptin levels are correlated with the degree of adiposity, especially in lean subjects, and confirm that circulating leptin levels are greater in obese subjects than lean subjects. The present study also failed to show a significant association between plasma leptin and insulin sensitivity in lean and obese women. Furthermore, plasma leptin and subcutaneous adipose tissue OB gene expression are not under short term regulation following feeding in fasted lean or obese female subjects.

Antidiabetic efficacy of BRL 49653, a potent orally active insulin sensitizing agent, assessed in the C57BL/KsJ db/db diabetic mouse by non-invasive 1H NMR studies of urine

High resolution 1H nuclear magnetic resonance (NMR) spectroscopic analysis of biofluids is a recently established tool for evaluating inherited and acquired errors in metabolic control. In the present study 1H NMR analysis of urine was used to monitor efficacy of BRL 49653, a potent and selective antihyperglycaemic agent, following oral administration for up to 36 weeks to the genetically diabetic C57BL/KsJ db/db mouse. The effects of BRL 49653 on carbohydrate and fatty acid metabolism were monitored by determination of changes in concentrations of low molecular weight urinary metabolites. A qualitative comparison of the NMR spectra of urine from untreated diabetic mice with those of lean littermates and literature examples revealed several abnormalities, the majority of which could be explained in terms of the non-insulin dependent diabetes syndrome exhibited by these animals. Quantitatively the most prominent was the extreme glycosuria of both young (8-12 weeks; 0.9 g glucose kg-1 h-1) and older (42 weeks; 2 g glucose kg-1 h-1) diabetic mice. This was accompanied by the excretion of a number of unassigned sugar derivatives and by ketone bodies. Administration of BRL 49653 (3 mumol kg-1) to db/db mice for 24 days reduced blood glucose concentrations to values comparable with non-diabetic lean littermates and reduced glycosuria by > 90%. BRL 49653 significantly reduced excretion of unassigned sugars, acetate, lactate, and the ketone bodies, acetoacetate, 3-D-hydroxybutyrate and acetone. The anti-diabetic efficacy of BRL 49653, assessed from the pattern of urinary metabolites, was maintained over a 36-week treatment period. These results demonstrate the value of 1H NMR to evaluate non-invasively the efficacy of novel therapeutic agents.

Effects of temperature on hematologic and serum biochemical profiles of hybrid striped bass (Morone chrysops x Morone saxatilis)

OBJECTIVE

To investigate the effect of water temperature on hematologic and biochemical analytes in hybrid striped bass.

ANIMALS

Hybrid striped bass (reciprocal cross: female Morone chrysops x male M saxatilis) maintained in 2,000-L tanks with undergravel filters.

PROCEDURE

Fish were acclimated to 10, 18, 24, and 29 C water for 6 weeks prior to sample collection. Hematologic and serum biochemical profiles were then determined. Values were compared among the various temperatures, and with reference intervals previously determined.

RESULTS

Most values were within or slightly outside the established reference intervals. The following analytes deviated notably from the reference interval: leukocyte, lymphocyte, and monocyte counts were lower than the reference intervals at 10 C; glucose values were lower at 10 and 18 C; calcium values were higher at 10 and 18 C; and total protein, albumin, globulin, and chloride values were higher at 29 C.

CONCLUSION

Separate reference intervals should be developed for analytes which, because of temperature, deviate notably from the reference interval. Modifications of the established reference intervals, by including fish from varied temperatures, should allow use of one reference interval for analytes, with only slight variation attributable to temperature.

CLINICAL RELEVANCE

Determining the effects of temperature on the hematologic and biochemical values helps develop clinical pathology as a diagnostic tool in fish.

Effects of ammonia and nitrate concentration on hematologic and serum biochemical profiles of hybrid striped bass (Morone chrysops x Morone saxatilis)

OBJECTIVE

To investigate the effects of poor water quality on hematologic and biochemical analytes in hybrid striped bass.

ANIMALS

Hybrid striped bass (reciprocal cross: female Morone chrysops x male M saxatilis) maintained in 2,000-L tanks with undergravel filters.

PROCEDURE

Fish were acclimated to high ammonia (0.15 mg/L) and nitrate (200 mg/L) concentrations for 6 weeks prior to sample collection. Hematologic and biochemical profiles were determined for these fish and for fish kept under normal conditions (control). Comparisons were made among the 3 water qualities and with reference intervals determined previously.

RESULTS

Significant differences in hematologic and biochemical analytes were observed between fish in the various groups; however, most of the values were within established reference intervals. All values from fish in the high ammonia concentration tank were either within the reference interval or not significantly different from control values. Fish from the high nitrate concentration tank had higher serum creatinine values and lower chloride values than did control fish, and both analytes were substantially outside the reference intervals.

CONCLUSION

High ammonia concentration of 0.15 mg/L did not affect any of the blood analytes measured. The hypercreatininemia and hypochloremia observed in fish from the 200 mg of nitrate/ml tank were considered to be pathologic changes associated with the high nitrate concentration.

CLINICAL RELEVANCE

Determining the effects of water quality on hematologic and biochemical values helps to develop clinical pathology as a diagnostic tool in fish.

The thiazolidinedione insulin sensitiser, BRL 49653, increases the expression of PPAR-gamma and aP2 in adipose tissue of high-fat-fed rats

The effects of the thiazolidinedione insulin sensitiser BRL 49653 on plasma leptin concentrations and on epididymal fat OB, PPAR-gamma and aP2 mRNA expression were examined in high-fat-fed and high-carbohydrate-fed adult Wistar rats. Diets were given for 4 weeks, with BRL 49653 (10 micromol/kg/day) administered by oral gavage for the last 4 days. Treatment with BRL 49653 reduced plasma leptin concentrations in high-fat-fed rats from 2.34 +/- 0.19 (n=9) to 1.42 +/- 0.09 (n=9) ng/ml (p<0.001). Plasma leptin was unaffected by BRL 49653 in the high-carbohydrate-fed rats. There was no difference in OB mRNA expression between high-fat-fed and high-carbohydrate-fed rats, with or without treatment. PPAR-gamma and aP2 mRNA expression were significantly increased in the high-fat-fed rats treated with BRL 49653 (p < 0.01 and p < 0.001 respectively), but not in carbohydrate-fed rats.

Retinoic acid receptors beta and gamma distinguish retinoid signals for growth inhibition and neuritogenesis in human neuroblastoma cells

Retinoids induce marked growth inhibition and neuritic differentiation in human neuroblastoma cells. Expression patterns of nuclear retinoic acid receptors (RAR) in embryonic and adult tissues suggests that RAR subtypes alpha, beta and gamma have tissue-specific functions. We have transfected a human neuroblastoma tumor cell line with a vector expressing either human RAR alpha, beta or gamma cDNAs. In the absence of exogenous retinoid, RAR beta transfectants demonstrated marked growth inhibition without morphologic evidence of differentiation, whereas transfectant clones overexpressing RARs alpha and gamma had no significant reduction in cell growth rates. Although RAR gamma transfectants were sensitive to the growth inhibitory effects of exogenous retinoids, these cells demonstrated resistance to the neuritogenic retinoid effects. Only RAR beta transfectants exhibited increased sensitivity to retinoids added in vitro. These results suggest that distinct neuritogenic and growth inhibitory signalling pathways exist in neuroblastoma cells and that RAR beta expression may be necessary for the retinoid growth inhibitory pathway.

Effect of foscarnet on quantities of cytomegalovirus and human immunodeficiency virus in blood of persons with AIDS

Four intravenous dosages of foscarnet given for 10 days were compared with no therapy in persons with AIDS who had asymptomatic cytomegalovirus (CMV) viremia. CMV viremia was quantitated by endpoint cell dilution microcultures, pp65 antigenemia assay, and measurement of CMV DNA in peripheral blood leukocytes by a quantitative-competitive PCR. Human immunodeficiency virus type 1 (HIV-1) viremia was quantitated by endpoint cell dilution microculture, serum p24 antigen assay, and PCR for HIV-1 RNA in plasma. Twenty-seven subjects who had received a median of 22 months of nucleoside antiretroviral therapy were enrolled. Twenty-two subjects received foscarnet, which was well tolerated and decreased the CMV burden, as reflected by all three indicator assays. During the 10 days of dosing, the level of CMV viremia, as measured by 50 percent tissue culture infective doses, decreased from 117.5 to 12.7 (P = 0.001), the amount of CMV DNA decreased from 20,328 copies to 622 copies per 150,000 leukocytes (P = 0.02), and the level of CMV pp65 antigenemia decreased from 14.9 to 1.6 positive peripheral blood mononuclear cells per 50,000 leukocytes (P = 0.008). A significant pharmacodynamic relationship was found between the peak foscarnet concentration and a decrease in the level of CMV antigenemia (P < 0.05). Foscarnet had no effect on quantitative HIV-1 microcultures during the 10 days of treatment, but the HIV-1 p24 antigen level in serum decreased significantly, from 454 to 305 pg/ml (P = 0.01). Also, a significant pharmacodynamic relationship was seen between plasma HIV-1 RNA concentrations and both peak foscarnet concentration (P < 0.01) and the area under the foscarnet time-concentration curve (P < 0.05). Reductions in the levels of CMV and HIV-1 viremia correlated quantitatively with systemic exposure to foscarnet, whereas control subjects actually experienced an increase in CMV and HIV-1 burdens. The dual antiviral activity of foscarnet shown in this trial encourages investigation of its use in combination with other antiretroviral therapies for persons with AIDS.

Nonsystemic vasculitic mononeuropathy multiplex, cryoglobulinemia, and hepatitis C

A 39-year-old man developed sequential acute mononeuropathies involving both median, both ulnar, and the right radial and left peroneal nerves. Electrophysiology demonstrated an asymmetric sensorimotor axonal polyneuropathy; nerve biopsy confirmed a vasculitis. Laboratory evaluation revealed a mixed cryoglobulinemia and active hepatitis C infection. The patient stabilized with prednisone/cyclophosphamide/interferon-alpha. Hepatitis C should be considered in the differential diagnosis of mononeuropathy multiplex. Accurate diagnosis is important, as interferon-alpha may prevent transition to chronic hepatitis/cirrhosis.

Toxicity and tolerability of recombinant human ciliary neurotrophic factor in patients with amyotrophic lateral sclerosis

We examined the toxicity of both single and multiple subcutaneous injections of recombinant human ciliary neurotrophic factor (rhCNTF) in 72 patients with ALS, in doses ranging from 2 to 100 micrograms/kg. Adverse events were generally dose related and ranged from mild to severe. The tolerability of daily subcutaneous rhCNTF was equivalent to placebo at doses < or = 5 micrograms/kg/day. At higher doses, anorexia, weight loss, reactivation of herpes simplex virus (HSV1) labialis/stomatitis, cough, and increased oral secretions occurred.

Central projections of persistent larval sensory neurons prefigure adult sensory pathways in the CNS of Drosophila

We have used a GAL4 enhancer-trap line driving the expression of a lacZ construct to examine the reorganisation of an identified group of proprioceptive sensory neurons during metamorphosis in Drosophila. The results show that whilst most larval sensory neurons degenerate during the first 24 hours of metamorphosis a segmentally repeated array of 6 neurons per segment persists into the adult stages to become functional adult neurons. These sensory neurons retain their axonal projections in the central nervous system intact and unchanged throughout. The adult sensory neuron axons enter the central nervous system at around 44 hours after puparium formation. Most of these axons grow along the pathways defined by the persistent larval sensory axons. The ordering of the adult sensory projections is, therefore, established upon the larval pattern of projections. The possibility that the larval neurons act as guidance cues for organising the ordered arrays of sensory neurons is discussed.

Amyotrophic lateral sclerosis and occupational history. A pilot case-control study

OBJECTIVE

To assess the association of a number of occupational and industrial exposures with amyotrophic lateral sclerosis (ALS).

DESIGN

A case-control study of ALS cases matched by age and sex to 2 controls each: 1 from a neurologic clinic and 1 from a local community. Exposures were ascertained by questionnaire, and patients were requested before the interview to be to prepared to supply occupational histories.

SETTING

Patients with ALS were enrolled at the University of Minnesota ALS Clinic in Minneapolis.

PATIENTS

Patients with ALS (n = 25) were from the University of Minnesota ALS clinic, and clinic controls (n = 25) were patients with other neuromuscular diseases from the university's Muscle Disease Clinic, selected on the basis of clinic enrollment date nearest to that of the matched case. Clinic controls were principally patients with myopathies. Community controls (n = 25) were selected from the community using a random-digit-dialing protocol matching on the first 5 digits of the case patient's telephone number.

RESULTS

The strongest association with disease was exposure to welding or soldering materials (odds ratio, 5.0) and the welding industry (odds ratio, 5.3). Electric plating showed a high odds ratio of 8 (95% confidence interval, 0.9-72.0), but low statistical significance (P < .07) Several exposures or industries, while not statistically different, showed enough difference that to ignore them might lead to a Type II error, a result of the pilot nature and small sample size. These included paint or pigment manufacturing, the petroleum industry, the printing industry, and shipbuilding.

CONCLUSIONS

The association with welding, soldering, and the welding industry is strong and suggests a need for further work. This is despite the small numbers studied, thus making most industrial or occupational exposures too limited to draw conclusions or detect associations. Perhaps the most obvious candidate from the welding, soldering exposure for a common toxin would be lead. Other suggestions of risk were seen for paint or pigment manufacture, shipbuilding, electric plating, and the dairy industry. The degree of association for these, while high, is not statistically significant, and suggests that there may be 1 or more environmental toxins common to those industries that need more precise measurement.

Physical activity, trauma, and ALS: a case-control study

AIMS

The association of trauma and physical activity with ALS is controversial. We explored the relation in a pilot case-control study.

MATERIAL AND METHODS

ALS patients were selected from a university muscle disease clinic and paired with two matched controls: one from the clinic, but having different diseases, and one from the community.

RESULTS

We found several strong and statistically significant differences between ALS cases and the matched controls. These included severe head, neck and back injury (OR = 5.3), the frequency of sweating in work (OR = 1.6) or leisure activity (also OR = 1.6), and earning a school letter (OR = 3.1). Other measures of trauma and activity, while not achieving statistical significance (p < 0.05), were in accord with these findings.

DISCUSSION

Possible explanations include trauma and vigorous exercise precipitating ALS; trauma as an early sign of disease; or a third factor associated with ALS predisposing to injury.

CONCLUSIONS

Severe head, neck, and back injury and frequency of sweating both in work and leisure activity showed a strong association with ALS. Further study could test narrower and less common exposures with greater statistical power.

Blood biochemical reference intervals for sunshine bass (Morone chrysops x Morone saxatilis) in three culture systems

OBJECTIVE

To determine and compare biochemical reference intervals for sunshine bass (hybrid striped bass) from 3 culture systems.

DESIGN

Observational comparison study.

ANIMALS

Clinically normal sunshine bass (reciprocal hybrid striped bass, female Morone chrysops x male M saxatilis raised in high-density recirculating systems (80 g/L), low-density tanks (5 g/L) with biofilters, and cages (70 g/L) in a fresh water pond.

PROCEDURE

Biochemical reference intervals were determined for fish from the different production systems following the National Committee for Clinical Laboratory Standards guidelines. Reference intervals from the 3 groups were compared.

RESULTS

Reference intervals were significantly different between sunshine bass in the various culture systems. Though most of the differences in reference intervals were minor, fish in the high-density recirculating system had higher concentrations of total protein, albumin, globulin, creatinine, and phosphorus, and lower chloride values. There were no significant differences in glucose concentrations among the 3 groups of fish, and no differences in cortisol concentrations between fish in tanks and cages.

CONCLUSIONS

Separate reference intervals should be developed for hybrid striped bass in different culture systems.

CLINICAL RELEVANCE

Determining biochemical reference intervals for hybrid striped bass provides a tool to assess the health status of these fish.