Thyroid hormone control of preganglionic innervation of the adrenal medulla and chromaffin cell development in the rat. An ultrastructural, morphometric and biochemical evaluation

In the rat, functional connections between the splanchnic nerve and the adrenal medulla are immature at birth and do not become fully competent until the first postnatal week. Neonatal administration of triiodothyronine (T3) accelerates this process, and the present study was undertaken to elucidate the underlying mechanisms. Rats were given T3 (0.1 mg/kg, s.c.) daily for 9 days beginning 1 day after birth. Preganglionic innervation of the adrenal medulla was examined by retrograde axonal transport of horseradish peroxidase (HRP). At 10 days of age, there was an increased number of labeled perikarya in the spinal cord of the hyperthyroid pups. Ultrastructural examination revealed a corresponding increase in synaptic density in the adrenal medulla and in the activity of choline acetyltransferase, a marker for preganglionic cholinergic nerve terminals. These effects were attenuated by 25 days of age, whereupon deficits in HRP-labeled neurons and adrenomedullary synapses were noted. Similarly, replication of chromaffin cells was enhanced transiently in the T3 group during the initial stage of hyperthyroidism, but subsequent long-lasting deficits in cell numbers were noted, along with a corresponding retardation of ontogeny of adrenal catecholamine biosynthesis and storage. Thus, neonatal hyperthyroidism accelerates synaptic development in the sympatho-adrenal axis but suppresses maturation of the target chromaffin cells, ultimately leading to impaired adrenomedullary function.

Nutritional influences on adrenal chromaffin cell development: comparison with central neurons

Neurotransmitter systems in the developing brain are generally protected from growth retardation associated with nutritional deprivation. To investigate if such protective mechanisms extend to similar tissues in the peripheral sympathetic system, maturation of the chromaffin cells of the adrenal medulla and development of their centrally derived splanchnic innervation were evaluated in rats whose nutritional status had been altered during the neonatal period by increasing (16-17 pups/litter) or decreasing (five to six pups/litter) the litter size from the standard (11-12 pups/litter). Ontogeny of adrenal catecholamine stores and activities of catecholamine-biosynthetic enzymes tyrosine hydroxylase and phenylethanolamine N-methyltransferase were monitored, along with activity of choline acetyltransferase, a marker enzyme for the preganglionic neurons innervating the chromaffin cells. Neonatal nutritional deprivation slowed body weight gain and retarded development of the chromaffin cells, as evidenced by subnormal catecholamine stores, tyrosine hydroxylase and phenylethanolamine N-methyltransferase activities. The effects persisted despite the complete recovery of body weights postweaning. The developmental alterations were not caused by overcrowding stress, as plasma corticosterone levels were not elevated in the large litter group. Neonatal nutritional enrichment promoted body weight gain but failed to enhance development of adrenal catecholamines; tyrosine hydroxylase and phenylethanolamine N-methyltransferase activities were elevated only in the preweaning period. In contrast to effects on the chromaffin cells, altered neonatal nutritional status had only minor, transient effects on the development of the centrally derived cholinergic innervation of the adrenal and produced only small changes (less than 10%) in brain tyrosine hydroxylase activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Teratogenic effects of nitrofen on cellular and functional maturation of the rat lung

The herbicide nitrofen was administered to pregnant Sprague-Dawley and Fischer-344 rats on Days 10-13 of gestation (po, 20 or 40 mg/kg daily) and the effects of maturation of the perinatal lung were evaluated. Nitrofen interfered with the ontogenetic acquisition of lung cells as DNA, RNA, and protein content were subnormal. The hypoplastic lungs in the newborns were associated with structural deficits, resulting in a profound reduction of surface area available for gas exchange and depressed lung compliance. Other factors which influence pulmonary function and systemic delivery of oxygen were also considered. Adrenal catecholamines, which play an important role in surfactant production and fluid resorption in the lung during the transition to air-breathing, were markedly reduced. In addition, red blood cell concentration was significantly diminished. Taken together, these results suggest that the neonatal mortality observed in the nitrofen-treated rats is likely associated with respiratory distress caused by a number of cellular and functional aberrations. These include (a) hypoplasia and structural defects in the lung leading to deficient pulmonary function, (b) deficits in adrenal catecholamines potentially impeding the transition of the lung to air-breathing, and (c) impaired systemic delivery of oxygen due to reduced hemoglobin concentration.

Activation of the adrenal cortex or the peripheral sympatho-adrenomedullary system does not necessarily influence milk ejection in the rat

Following a 5-h isolation period, primiparous rats have the same milk supply on days 8/9 and 13/14 post partum, yet in response to suckling they release a greater amount of milk at the latter time. Inasmuch as stress is known to inhibit lactation and handling of the pups is stressful to the dams, the question arose as to whether separation from pups before nursing constitutes a greater stress for the dam at the earlier stage of lactation. This possibility was explored in the present study: As an index of stress, changes in plasma corticosterone were measured from chronically cannulated dams. In addition, the role of adrenal hormones and the peripheral sympathetic nervous system in the regulation of milk ejection under these experimental conditions was assessed following bilateral adrenalectomy and treatment with pentolinium, a ganglionic blocker which does not cross the blood-brain barrier. Corticosterone pellets were implanted subcutaneously following adrenalectomy in order to maintain proper lactation. From the results obtained, lactators demonstrated a greater increase in plasma adrenocorticosteroid levels in response to nursing on day 8/9 than on day 13/14 post partum, but milk yield was significantly less at the earlier than at the later stage of lactation. Adrenalectomy in conjunction with corticosterone replacement pellets did not alter milk supply or milk release. The subsequent treatment with pentolinium did not affect milk ejection. Pups still ingested less milk on day 9 than on day 13/14. It is suggested here that the isolation/suckling condition imposed on lactators may be more stressful earlier in lactation. Inasmuch as removal of the adrenal hormones along with ganglionic blockade did not modify the amount of milk ingested by the pups, it is concluded that the smaller milk release observed on day 9 post partum does not result from a direct suppression by the adrenal hormones or by the peripheral sympathetic nervous system on milk ejection.

Role of sympathetic neurons in biochemical and functional development of the kidney: neonatal sympathectomy with 6-hydroxydopamine

Renal sympathetic function develops over the first 3 weeks of postnatal life in the rat. In the current study, the effects of neonatal sympathectomy with 6-hydroxydopamine were examined on renal biochemical and functional development. The completeness and persistence of sympathetic nerve loss were confirmed by direct measurement of norepinephrine levels and turnover. Evidence was obtained for adverse effects on cellular maturation, as shown by perturbations in the ornithine decarboxylase/polyamine system, which is controlled partially by beta adrenergic input and which regulates macromolecule synthesis in developing cells. A later phase of 6-hydroxydopamine-induced alterations in renal development was seen during the period in which synaptogenesis is prominent and sympathetic tone is high (end of the 2nd postnatal week to end of the 3rd week): the denervated kidneys displayed supersensitivity of beta adrenergically mediated cyclic AMP responses without changes in receptor binding. The alterations in biochemical indices of cellular maturation were accompanied by abnormalities of renal function. 6-Hydroxydopamine caused an increase in the fractional excretion of sodium and deficits in physiological responsiveness of the kidney to a vasopressin analog. Later on, alterations in glomerular filtration rate and basal urinary osmolality also were prominent. These results indicate that neonatal sympathectomy has an adverse effect on the biochemical and functional development of the kidney.

Sensitivity and specificity of the extended scale for dementia

The Extended Scale for Dementia was introduced as a test for grading the intellectual function of patients with dementia. Its use in discriminating demented patients from nondemented control subjects has been explored. The test had a sensitivity of 93% and a specificity of 96% in patients over the age of 65 years, but the sensitivity fell to 75% in those younger than 65 years. The scale may be useful, particularly for patients over the age of 65 years, in helping to distinguish dementia from normality.

A new method for the artificial raising of infant rats: the palate cannula

Chronic removal of infant rats from their mother prior to the onset of weaning is complicated by the fact that young rats do not easily suckle from an artificial nipple. Thus, a method of artificial raising is advantageous for developmental investigations of nutrition or ingestive behaviors during the suckling period. The intragastric cannula has become a popular method for this purpose. However, for many studies, it would be advantageous if the diet could be administered to the mouth and actually swallowed by the young rat. We developed a new cannulation procedure which accomplishes these goals. Infant rats were removed from their mother on postnatal day 13 and fitted with a cannula that opened into the oral cavity through the hard palate. Liquid diet was administered by an infusion pump through the cannula for the subsequent 5 days. Growth was assessed by daily measures of body and organ weight. The results indicate that from postnatal day 13 on, the palate cannula can allow the continuation of normal growth patterns and eliminates certain complicating factors associated with other forms of artificial raising.

Central and sympatho-adrenal responses to insulin in adult and neonatal rats

In the mature rat, subcutaneous administration of insulin (0.02 IU/g body wt.) produced hypoglycemia and a profound activation of the sympatho-adrenal pathway, as indicated by a marked depletion of adrenal catecholamines. Cellular glucopenia caused by administration of 2-deoxyglucose also produced a sympatho-adrenal response. In contrast, in 2-day-old rats, the systemic injection of insulin evoked only a small depletion of catecholamines even though severe hypoglycemia was present, and 2-deoxyglucose also produced a diminished response. The central administration of insulin at an equivalent dose (0.02 IU/g brain) stimulated brain ornithine decarboxylase activity in both neonates and adults, but was ineffective in evoking hypoglycemia or adrenal catecholamine release. These results suggest that: (a) direct interaction of insulin with its receptors in the central nervous system is not required for activation of the sympatho-adrenal pathway, and (b) the lack of sensitivity of neonatal adrenal catecholamine release to subcutaneous administration of insulin is likely associated with immaturity of splanchnic neurotransmission rather than with absence of central insulin receptors or impaired peripheral responsiveness to insulin.

Platelet glycoprotein IIb. Chromosomal localization and tissue expression

The GPIIb-IIIa complex functions as a receptor for cytoadhesive proteins on the platelet surface. Both GPIIb and GPIIIa are synthesized by a human erythroleukemia (HEL) cell line. We isolated several cDNA clones by screening a HEL cell cDNA library with an oligonucleotide derived from amino acid sequence of GPIIb. Nucleotide and amino acid sequences were determined from 703 bp of one of these clones. Amino acid sequence of purified platelet GPIIb peptides confirmed the identity of the clone. The cDNA encodes the carboxyl terminus of the large (alpha) subunit of GPIIb and all of the smaller (beta) subunit of GPIIb. By hybridizing the cDNA directly to chromosomes separated by dual laser chromosome sorting, the gene for GPIIb was mapped to chromosome 17. Northern blot analysis showed a approximately 3.4-kb GPIIb mRNA in HEL cells. We also compared the amino acid sequences determined from eight additional platelet GPIIb peptides with the derived amino acids from a published HEL cell GPIIb cDNA, and the platelet and HEL cell proteins appear to be the same. Despite previous reports that vascular endothelial cells and monocytes contain GPIIb, no GPIIb mRNA was observed in either type of cell. Thus, GPIIb appears to be specific for the platelet-megakaryocyte membrane and is distinct from the alpha subunits of the adhesion receptors in other normal tissues.

Regulation of adrenal chromaffin cell development by the central monoaminergic system: differential control of norepinephrine and epinephrine levels and secretory responses

In the mature rat, reflex sympathetic stimulation by insulin-induced hypoglycemia resulted in profound depletion of adrenal epinephrine, and to a lesser extent, norepinephrine. In the developing rat, insulin evoked little or no secretory response from the adrenals prior to 1 week of age. By 7 days, a moderate depletion of epinephrine was seen and the magnitude of the response increased with age. In contrast, during the first 3 weeks of postnatal life, insulin failed to deplete norepinephrine from the adrenal medulla and in fact, produced an increase. This chiefly resulted from de novo biosynthesis of the amine, as the rise was blocked by alpha-methyl-p-tyrosine. These results suggest that the ontogeny of the two chromaffin cell types (norepinephrine and epinephrine-containing) in the adrenals and the maturation of their secretory responses are under differential regulation. Because descending supraspinal catecholaminergic and serotonergic systems have been implicated to play key roles in regulating adrenomedullary function, the ontogeny of the sympatho-adrenomedullary axis was evaluated after neonatal central lesioning with 6-hydroxydopamine or 5,7-dihydroxytryptamine. 6-Hydroxydopamine resulted in a preferential elevation of epinephrine in the developing adrenals as well as an increase in the responsiveness of the adrenals to reflex stimulation by insulin; the mature secretory pattern was obtained as early as at 4 days postnatally for epinephrine and 9 days for norepinephrine. In contrast, 5,7-dihydroxytryptamine led to a preferential reduction of basal adrenal norepinephrine content.(ABSTRACT TRUNCATED AT 250 WORDS)

Central adrenergic receptor changes in the inherited noradrenergic hyperinnervated mutant mouse tottering

Adrenergic receptor binding characteristics were analyzed in the mutant mouse tottering (tg/tg), a single gene locus autosomal recessive mutation causing hyperinnervation by locus coeruleus neurons of their target regions, which results in epilepsy. Instead of the expected down-regulation of receptors due to the hyperinnervation, both [3H]prazosin (alpha 1-receptor) and [125I]iodopindolol (beta-receptor) binding were normal in the tg/tg hippocampus, spinal cord and slightly increased in the cerebellum. This lack of postsynaptic receptor modulation in the target cells, combined with increased levels of norepinephrine due to the aberrant axon growth, may the critical factors in the expression of the abnormal spike-wave absence seizures in the tg/tg mouse.

Origin of defective T lymphocyte-suppressor activating factor interaction in patients with rheumatoid arthritis

We previously examined the generation of T cell released suppressor activity (TRSA) from peripheral blood T cells from patients with rheumatoid arthritis (RA) in response to a soluble suppressor activating factor (SAF) produced by a 6-thioguanine resistant mutant of the human T cell line CEM. We reported (Lau et al., 1985 Clin. exp. Immunol. 61, 481) that T cells from a substantial proportion of RA patients exhibited impaired TRSA release. To delineate further the TRSA abnormality observed in patients with active RA, we evaluated the kinetics of SAF activation, precursor frequency of SAF reactive cells and quantity of activated SAF released on a per cell basis. The results showed that a lower precursor frequency of SAF reactive cells accounted for defective TRSA release in a majority of RA patients, while TRSA release on a per cell basis was normal. The defective TRSA response to SAF could not be explained by abnormal dose kinetics of SAF, time kinetics of TRSA release or prior in vivo lymphocyte activation of the RA T cells.

T cell-derived factor alone or in combination with immunosuppressive drugs augments prolongation of allogeneic skin graft survival in mice receiving donor-specific transfusion

Limiting dilution cytotoxicity or proliferation assays were performed with cells taken from A/J mice pretransfused with BALB/c blood. The data obtained indicate that donor-specific transfusion decreased both the frequency of reactive precursors and their proliferative potential after activation. Additional studies implied that these changes may be associated with a serum- or cell-mediated antigen-specific suppressive mechanism. Further manipulations aimed at preferentially sparing or enhancing the activity of suppressor T cells prolonged skin graft survival in pretransfused mice and led to the presence of suppressor T cells in the spleen of such mice, which were active upon adoptive transfer. These manipulations included the use of pretransplant donor-specific transfusion, administration of ALS or cyclosporin-A, or the use of posttransplant injection with a T suppressor activating factor (SAF). Optimum graft survival was associated with combined treatment when using transfusion, SAF, and cyclosporin-A.

T cell-derived factor alone or in combination with immunosuppressive drugs augments prolongation of allogeneic skin graft survival in mice receiving donor-specific transfusion

Limiting dilution cytotoxicity or proliferation assays were performed with cells taken from A/J mice pretransfused with BALB/c blood. The data obtained indicate that donor-specific transfusion decreased both the frequency of reactive precursors and their proliferative potential after activation. Additional studies implied that these changes may be associated with a serum- or cell-mediated antigen-specific suppressive mechanism. Further manipulations aimed at preferentially sparing or enhancing the activity of suppressor T cells prolonged skin graft survival in pretransfused mice and led to the presence of suppressor T cells in the spleen of such mice, which were active upon adoptive transfer. These manipulations included the use of pretransplant donor-specific transfusion, administration of ALS or cyclosporin-A, or the use of posttransplant injection with a T suppressor activating factor (SAF). Optimum graft survival was associated with combined treatment when using transfusion, SAF, and cyclosporin-A.

Mammary resistance: a possible controlling factor in milk ejection

At 8 and 13 days post partum, rats have the same total milk availability; yet, in response to suckling they release a greater amount of milk on day 13 than on day 8. Increased sensitivity to suckling in the more advanced lactators may result from a greater release of oxytocin or from changes in the mammary glands as lactation advances. The present study explores this latter possibility in anaesthetized dams at 8-9 and 13-15 days of lactation. Milk release and intramammary pressure were measured in anaesthetized dams in response to various doses of oxytoxin. Milk release was determined from the body weight gain of pups which had been fasted for 5 h before suckling on dams which had been isolated for 5 h. This parameter was significantly greater in 13- to 15-day lactators than in 8- to 9-day lactators over the range of oxytocin doses examined. In contrast, intramammary peak pressure and its dissipation time were significantly larger in the 8- to 9-day lactators than in the 13- to 15-day lactators. The compliance of the mammary glands was indirectly assessed at the two stages of lactation. When a constant pressure pulse was introduced into a cannulated gland, the resulting pressure peak was significantly greater in 8-day than in 13-day lactators, indicating a greater resistance in the former. Taken together, these results indicate that when endogenous oxytocin is inhibited (by anaesthesia) the greater milk release observed at the later stage of lactation in response to various doses of oxytocin may be due to a decline in mammary resistance as lactation progresses.

Interobserver variation in computed tomography of the brain

As part of the University of Western Ontario Dementia Study, the computed tomographic brain scans of 16 patients were reviewed by three neuroradiologists. The size of the ventricles and sulci were rated using a six-point scale. Infarction and white matter changes were assessed in accordance with specified criteria. The interobserver correlations in this small series were statistically significant in 17 of 20 items, and good or acceptable for infarction, leuko-araiosis, and ventricular size. It is suggested that the use of rigid criteria for the definition of abnormality helps to promote interobserver agreement.

Cognitive and neurologic findings in demented patients with diffuse white matter lucencies on computed tomographic scan (leuko-araiosis)

A series of patients referred to the University of Western Ontario, London, Dementia Study for investigation of possible dementia underwent computed tomographic scans, psychometric testing (Extended Scale for Dementia [ESD]), and neurologic examination. Thirty-nine of the 113 patients studied (ischemic score, less than or equal to 4) were found to have leuko-araiosis, which we have defined as patchy or diffuse lucencies in the white matter. Patients with leuko-araiosis had significantly lower mean scores on the ESD, 109.7 +/- 61.2, compared with mean scores of 148.5 +/- 78.0 in those without. However, only a trend toward lower scores on the ESD was observed when age, sex, education, and infarct were taken into account in the analysis of covariance. Leuko-araiosis was found to be associated with increasing age, hypertension, abnormalities of power in the limbs, and extensor-plantar responses in this sample of patients. In patients with Alzheimer's disease (AD) alone, diagnosed clinically, 29 out of 91 demonstrated leuko-araiosis on computed tomography, but scores on the ESD in this group overall were not significantly different when those with and without leuko-araiosis were compared. In less advanced cases, however, a highly significant trend was evident for leuko-araiosis to be associated with increased dementia in AD. The results are consistent with the hypothesis that leuko-araiosis is associated with dementia in AD, and that this is either most marked or most easily identifiable before the dementia becomes very severe.

Vascular risk factors and leuko-araiosis

Leuko-araiosis was found in 49 of 140 demented patients compared with 12 out of 110 control subjects. Thirty-one of 95 patients with dementia of the Alzheimer's type had leuko-araiosis. A history of stroke was four times more frequent in patients with leuko-araiosis than in those without leuko-araiosis (17.4% and 4.4%, respectively). It occurred in 25% of controls with leuko-araiosis compared with only 2% of those without leuko-araiosis. Mean systolic blood pressure was associated with leuko-araiosis. No association was found for diastolic blood pressure, myocardial infarction, angina, diabetes, or carotid bruits. On logistic regression analysis, the strong association between dementia and leuko-araiosis was mainly explained by a history of stroke. There are common factors in leuko-araiosis and stroke, but stroke alone does not account for leuko-araiosis.

The clinical diagnosis of Alzheimer's disease

Clinical and pathologic diagnoses are compared in 65 patients who had dementia and who had been studied longitudinally during life. The sensitivity of diagnosis for dementia of the Alzheimer type (DAT) without any other diagnosis was 87%, and the specificity was 78%. The ischemic scale score did not discriminate well between patients with pure multi-infarct dementia and those with both DAT and multi-infarct dementia. However, 35 of 38 cases of pure DAT had a score of 4 or less on the ischemic scale.

The electroencephalogram in Alzheimer-type dementia. A sequential study correlating the electroencephalogram with psychometric and quantitative pathologic data

As part of a longitudinal cohort study of dementia, 139 patients with Alzheimer's disease (dementia of the Alzheimer type, senile dementia of the Alzheimer type, and mixed type [ischemic score, 4 to 7]) and 148 age-matched control subjects were evaluated for electroencephalographic (EEG) abnormalities and their evolution. Electroencephalograms were significantly different in the two groups; EEGs worsened overall in the two groups during a period of one to four years, but most subjects showed no alteration in their EEGs. Some patients showed improvement in their EEG findings during the follow-up period. A strong correlation between EEG grade and psychometric scores was consistently found over sequential studies. In a subgroup of patients on whom autopsies were performed, morphometric neuron loss correlated significantly with EEG severity.

Electrocardiographic findings in 204 residents of homes for the aged

Electrocardiograms from 204 subjects aged 60 and above, residing in homes for the aged, were analysed. 13% had evidence of cardiovascular disease. 55% of the electrocardiograms showed at least one abnormality. At least 10% of electrocardiograms showed left atrial hypertrophy, first degree atrioventricular block, right bundle branch block, pathologic Q waves, ST-T abnormalities, or prolonged QT interval. Findings predictive of cardiovascular disease were left ventricular hypertrophy patterns and ST-T abnormalities, or prolonged QT interval. Findings predictive of cardiovascular disease were left ventricular hypertrophy patterns and ST-T abnormalities. Increase of age from 60 to 100 years was associated with prolongation of PR and QT intervals, but shortening of the RR interval.

Cognitive and neurologic findings in subjects with diffuse white matter lucencies on computed tomographic scan (leuko-araiosis)

As part of a prospective clinicopathologic study, a cohort of 105 "normal" elderly volunteers was investigated with computed tomographic scans, psychometric testing (Extended Scale for Dementia [ESD]) and neurologic examination. Computed tomographic scans were evaluated for the presence or absence of white matter lucencies, termed leuko-araiosis. These are defined as patchy or diffuse areas of decreased attenuation involving only white matter and with no change in adjacent ventricles or sulci. The nine controls with leuko-araiosis had lower scores on the ESD than the 96 controls without leuko-araiosis (mean ESD with leuko-araiosis, 227.1 +/- 14; without leuko-araiosis, 237.1 +/- 8), and the difference remains significant even after adjusting for the possible confounding effects of age, sex, education, and infarct detected on computed tomography. Significant differences were also found comparing subjects with leuko-araiosis and those without in respect to abnormal gait, limb power, plantar response, and the rooting and palmomental reflexes. Leuko-araiosis may represent a marker for early dementia. The pathophysiology of this finding remains uncertain. Our results suggest that white matter abnormalities play a role in the development of intellectual impairment in the elderly.

Effects of prenatal nitrofen exposure on cardiac structure and function in the rat

The herbicide nitrofen was administered to pregnant Fischer-344 and Sprague-Dawley rats on Days 10-13 of gestation (po, 20 or 40 mg/kg daily) and its effects on cardiac structure and function were investigated in the offspring. In the 21-day fetuses, nitrofen did not influence intrauterine growth or basal heart rate. In contrast, the herbicide produced a marked depression of heart rate and abnormal electrocardiographic (ECG) profiles in the newborn rats, in conjunction with labored respiratory movements and a profound increase in postnatal mortality. A few animals displayed cardiac ventricular septal defects and diaphragmatic hernias but these malformations did not appear to be associated with the ECG changes. The chronotropic deficiencies seen in the nitrofen-treated pups were reversible by acute hyperoxia (40% oxygen). These results suggest that the teratogenic effects of nitrofen on cardiac physiology and on postnatal mortality cannot be accounted for solely by specific gross anatomical damages to the rat heart and diaphragm; rather, other more subtle morphological and physiological factors which contribute to improper systemic delivery and cellular utilization of oxygen may be involved.

Impaired release of a T-cell specific suppressor factor in rheumatoid arthritis

Peripheral blood T cells from patients with rheumatoid arthritis (RA) and scleroderma (PSS) were assessed for their ability to release T-cell-specific suppressor activity (TRSA) upon incubation with a suppressor activating factor (SAF) derived from a human lymphoblastoid cell line (CEM). T cells from 11/20 (55%) RA patients exhibited impaired TRSA release in contrast to 1/12 (8%) of PSS patients. RA patients demonstrating impaired TRSA release exhibited more active arthritis than patients demonstrating normal TRSA release.

Investigation of the nature of the "stretch response" in suckling rats

The "stretch response" in suckling rats has commonly been used as an index of milk ejection and milk intake. In the current study, we have compared the behavior of pups suckling on dams with either full, empty or ligated mammary glands. In response to an IV bolus of oxytocin, pups suckling on both full and empty nipples displayed the characteristic stretch behavior. Lack of milk release from the latter nipples was confirmed by lack of weight gain by the pups. In contrast to pups suckling on intact nipples, those suckling on ligated nipples did not display the stretch response. It is concluded that this behavior occurs in response to erection of the nipple and is not necessarily associated with milk release.

Development of serotonergic and adrenergic receptors in the rat spinal cord: effects of neonatal chemical lesions and hyperthyroidism

The sympathetic preganglionic neurons in the spinal cord receive dense serotonergic (5-HT) and catecholaminergic (CA) afferent inputs from the descending supraspinal pathways. In the rat spinal cord, the levels of these biogenic amines and their receptors are low at birth, but undergo rapid ontogenetic increases in the ensuing 2-3 postnatal weeks until the adult levels are reached. In many systems it has been shown that denervation of presynaptic neurons leads to an up-regulation of the number of postsynaptic receptors. To determine whether the 5-HT and CA receptors in the developing spinal cord are also subject to such transsynaptic regulation, we examined the ontogeny of serotonergic receptors and alpha- and beta-adrenergic receptors in thoracolumbar spinal cord of rats given neurotoxins which destroy serotonergic (5,7-dihydroxytryptamine (5,7-DHT)) or noradrenergic (6-hydroxydopamine (6-OHDA)) nerve terminals. Intracisternal administration of 5,7-DHT or 6-OHDA at 1 and 6 days of age prevented, respectively, the development of 5-HT and CA levels in the spinal cord. Rats lesioned with 5,7-DHT displayed a marked elevation of 5-HT receptors with a binding of 50% greater than controls at 1 week and a continuing increase to twice normal by 4 weeks. A similar pattern of up-regulation was also detected with the alpha-adrenergic receptor, as rats lesioned with 6-OHDA exhibited persistent increases in receptor concentration. However, in these same animals ontogeny of the beta-adrenergic receptor in the spinal cord remained virtually unaffected by the chemical lesion. In several other parts of the nervous system, it has been demonstrated that the beta-adrenergic sensitivity can be modulated by hormonal signals, particularly that of the thyroid hormones. This phenomenon was examined in the spinal cord and in confirmation with previous studies neonatal treatment of triiodothyronine (0.1 mg/kg, s.c. daily) was capable of evoking persistent increases in beta-adrenergic receptor binding. These results suggest that: (a) development of the postjunctional serotonergic and alpha-adrenergic receptors in the rat spinal cord can occur in the absence of the prejunctional nerve terminals and are subject to transsynaptic modulation; (b) beta-adrenergic receptors in the spinal cord also can develop after prejunctional lesions but are regulated by hormonal rather than neuronal factors.

Regulation of milk ingestion in the infant rat

The aim of this study was to differentiate between maternal and offspring factors involved in the control of milk ingestion. Specifically, we investigated: (1) the temporal pattern of milk ingestion in fasted and non-fasted sucklings; (2) the amount of milk released as compared to that of milk available; and (3) the roles of the age of pups and the lactational stage of the dam as determinants of milk release. There were three general findings. First, the temporal pattern of milk letdown following a 5-hr accumulation consisted of an initial rapid phase followed by a slow "maintenance" phase. Second, a limiting factor in the amount of milk released is the dam's sensitivity to the suckling stimulus which changes as lactation progresses. Third, the age of the pups does not appear to play a determining role in milk release, but the degree of their deprivation does. In summary, it is suggested that compensation for weight loss during a fast in infant rats depends on an interplay between the pups' ability to increase their own intake, the milk availability, and the maternal sensitivity to suckling.

Conditions influencing formation of 16:0/16:0 molecular species in membrane phospholipids of Escherichia coli

Growth of a beta-oxidation-negative (fadE) strain of Escherichia coli in liquid culture with exogenous palmitate leads to the accumulation of 16:0/16:0 molecular species of phospholipid resulting in a temporary decrease in growth rate and lysis of a variable fraction of the cell population. Under the same growth conditions, this behavior is not seen in the closely related fadE+ parent strain which accumulates more modest levels of 16:0/16:0 together with 16:0/14:0. Based on differential scanning calorimetric measurements, 75.8 and 17.5% of the lipids from 16:0-enriched fadE and fadE+ cells, respectively, were found to be in the gel state at the growth temperature. Kinetic studies reveal the translocation of 16:0/16:0 molecular species from inner to outer membrane delays briefly the accumulation of this species in the inner membrane. This extreme and deleterious change in membrane-lipid composition precludes cloning of the fadE strain on solid media containing 16:0 and, therefore, these conditions provide the basis for selection of mutants altered in the mechanisms which determine the synthesis or accumulation of membrane lipid. Three such mutants are described which display alterations in the normal distribution of molecular species.

Maturation of sympathetic neurotransmission in the rat heart. IX. Development of transsynaptic regulation of cardiac adrenergic sensitivity

The number of beta adrenoceptors and the cardiac sensitivity to adrenergic stimulation increase substantially in the immediate postnatal period of the rat. To determine whether transsynaptic input influences this developmental process, the effects of a sympathomimetic and of agents which destroy noradrenergic nerve terminals on regulation of adrenergic postsynaptic sensitivity were compared in hearts from adult and developing rats. In mature animals, chronic exposure to the beta agonist isoproterenol (2.5 mg/kg s.c.) led to rapid onset (3-5 days) of chronotropic adrenergic subsensitivity accompanied by a loss of beta adrenoceptor binding sites; chemical sympathectomy by daily administration of guanethidine (50 mg/kg s.c.) or by 6-hydroxydopamine (100 mg/kg s.c. given once daily for 3 days) resulted in chronotropic adrenergic supersensitivity and increases in binding sites. These data in the adult agree with classical transsynaptic modulation of adrenergic postsynaptic reactivity. In contrast, identical drug treatments of immature rats beginning 1 day after birth failed to evoke changes in either chronotropic adrenergic sensitivity or in numbers of beta adrenoceptor binding sites until the 3rd to 4th week. Consequently, the initial development of beta adrenoceptors and responsiveness to catecholamines in the neonatal myocardium are not transsynaptically regulated; rather, other (e.g. hormonal) factors appear to control early maturation of cardiac adrenergic sensitivity.

Development of polyamine and biogenic amine systems in brains and hearts of neonatal rats given dexamethasone: role of biochemical alterations in cellular maturation for producing deficits in ontogeny of neurotransmitter levels, uptake, storage and turnover

Excessive levels of glucocorticoids are thought to interfere with synaptic development in the central nervous system. In the present study, dexamethasone given to newborn rats produced deficits in brain growth associated with shifts in the developmental pattern of the ornithine decarboxylase/polyamine system consistent with delays in cellular maturation. The effects on the brain were of smaller magnitude and shorter duration than those on the heart or on general growth and were indicative of "brain sparing." Although some biochemical indices of synaptic development of central noradrenergic systems ([3H]norepinephrine uptake into synaptosomes) were quantitatively deficient on a whole-brain basis, the reductions never exceeded the magnitude of effect on brain weight; for other indices (transmitter levels, [3H]norepinephrine into synaptic vesicles), there were little or no apparent developmental deficits. Thus, the effects of dexamethasone on synaptic development in the brain may not reflect a specific action of glucocorticoids over and above their more general effects on cellular maturation. In contrast to the lack of specific action on biochemical indices of synaptic outgrowth, neonatal dexamethasone did cause alterations in norepinephrine synthesis and turnover in both central and peripheral sympathetic neurons which could contribute to the physiological and behavioral abnormalities associated with glucocorticoid treatment during development.

Immunoregulatory T cell subpopulations in patients with scleroderma using monoclonal antibodies

Twenty-eight patients with scleroderma were compared with 22 healthy age-matched subjects. Monoclonal antibodies were used to detect the whole T cell population (OKT3), T helper cells (OKT4), and T suppressor/cytotoxic cells (OKT8) by indirect immunofluorescence on isolated peripheral blood mononuclear cells. A subset of scleroderma patients (i.e. 30% or eight of 28 patients) exhibited an elevated ratio of OKT4/OKT8 cells which could be accounted for, mainly by a reduction in OKT8 cells compared with controls. The scleroderma patients with an elevated OKT4/OKT8 ratio tended to be younger, have a shorter disease duration and more extensive skin involvement than patients with a normal OKT4/OKT8 ratio. There was no correlation with the presence of autoantibodies, drug therapy, or HLA-DR type. In order to further determine whether this imbalance in immunoregulatory cell subpopulations was specific for scleroderma, we further studied 16 patients with psoriatic arthritis but without manifest autoimmunity and delineated a similar subset of patients with an elevated OKT4/OKT8 cell ratio (i.e. 38% or six of 16 patients). The results demonstrate similar immunoregulatory T cell imbalances in patients with scleroderma and psoriatic arthritis. These findings suggest that numerical imbalances in lymphocyte subpopulations may not be specific for autoimmune disorders.

Neonatal hyperthyroidism causes premature development of baroreceptor-mediated cardiac sympathetic reflexes

Baroreceptor-mediated reflex control of cardiac sympathetic activity does not appear fully until the third week of postnatal age in the rat, possibly because central processing of baroreceptor sensory input is deficient in the neonate. Hyperthyroidism, which accelerates synaptogenesis in the peripheral sympathetic and central nervous systems, was produced by administering 3,3',5-triiodothyronine (T3) daily, and effects on development of baroreceptor-mediated sympathetic reflexes were evaluated. To test baroreceptor-mediated reflexes, control and T3-treated rats of different ages were given hydralazine acutely to produce a decrease in blood pressure, which in adult rats results in a large, sympathetically-mediated stimulation of cardiac ornithine decarboxylase (ODC) activity. In control neonates, cardiac ODC responses to hydralazine were absent until the 3rd week of age, but the T3-treated animals showed increases as early as 8 days of age. Furthermore, increased turnover of norepinephrine in cardiac sympathetic nerves in response to the hydralazine-induced hypotension was 2- to 3-fold higher in the 8-day-old T3-treated animals than in controls. These data indicate that the early appearance of the ODC response to hypotension in hyperthyroid rats results, at least in part, from precocious development of the ability of baroreceptor input to influence efferent sympathetic function.

Stimulation of rat heart ornithine decarboxylase by isoproterenol evidence for post-translational control of enzyme activity?

The activity of rat heart ornithine decarboxylase (ODC), the enzyme involved in the initial step of polyamine biosynthesis, was markedly stimulated after isoproterenol treatment, reaching a maximum of about four times the basal value four hours after administration. At all times after isoproterenol, kinetic studies revealed only two forms of the enzyme with Km values for ornithine of 35-50 microM and 190 microM, compared to only one form (190 microM) in the controls. At no time was a form of ODC with an intermediate Kornm detected, nor did dialysis reverse stimulation of activity of enzyme from isoproterenol-treated rats, or increase activity in control preparations; it is therefore unlikely that small molecular activators or inhibitors participate in the stimulation. The time course of Vmax values for the high-affinity component of the enzyme coincided with that of net enzyme activity, indicating that increases of ODC activity in response to isoproterenol might result from a shift of enzyme from its low-affinity state to the high-affinity form, rather than from appearance of additional enzyme molecules. In support of this hypothesis, alpha-difluoromethylornithine, an irreversible ODC inhibitor, displayed identical ID50 values in control and isoproterenol-treated animals, a situation which would not occur if more enzyme were present. These data are consistent with the view that post-translational control mechanisms involving macromolecular factors could operate in regulating cardiac ODC activity.

The effect of Davallina Orientalis on bone healing--a preliminary report

A crude methanol extract of the herb Davallina Orientalis was given intraperitoneally to test its effect on bone healing in mice. The results indicated that it could increase the breaking strength of a fracture site. In our experimental model, the lower dosage has a better result probably because of less toxicity.

Maturation of sympathetic neurotransmission in the rat heart. IV. Effects guanethidine-induced sympathectomy on neonatal development of synaptic vesicles, synaptic terminal function and heart growth

Sympathetic nerve input has been proposed to regulate cardiac growth and differentiation. In the present study, this hypothesis was tested by giving the neurotoxic adrenergic neuron blocking agent, guanethidine (50 mg/kg, s.c.), daily to rats for 21 consecutive days to produce long-term peripheral sympathectomy in neonatal rats. Ontogeny of the sympathetic nerve terminal was measured by the ablity of synaptic vesicle preparations to take up radiolabeled norepinephrine, and heart growth in the sympathectomized animals was monitored by organ weight as well as by RNA and protein synthesis. Guanethidine treatment produced a massive sympathectomy, as synaptic vesicle development was totally arrested; the functional consequence of this treatment was confirmed by the attenuation of chronotropic responses to tyramine, a drug which acts by displacement of norepinephrine from the noradrenergic terminal. Despite the clear-cut effectiveness of guanethidine to prevent formation of functional sympathetic innervation of the heart, no significant alterations in heart growth or RNA and protein synthetic capabilities were observed in the developing rats. These results suggest that the presence of sympathetic innervaton is not obligatory for normal growth of the heart to occur.

OKT3 induces suppressor cells for mixed lymphocyte and PHA mitogenic responses in human peripheral lymphocytes

Human peripheral lymphocytes pretreated with the Orthoclone monoclonal anti-T cell antibody OKT3 for 48 h markedly suppressed the proliferative response of autologous lymphocytes in one-way MLC and the mitogenic response to PHA. The ability to induce suppression is specific to OKT3 since other monoclonal antibodies to human T cells (OKT1, OKT4 and OKT8) did not elicit similar responses, OKT3 is mitogenic but further proliferation of OKT3 pretreated lymphocytes was not required for the suppression of autologous lymphocytes since mitomycin-C treated cells were fully effective. Kinetic studies indicated that pretreatment of lymphocytes with OKT3 for 24 h was sufficient to induce marked inhibition of the mitogenic response of autologous lymphocytes to PHA whereas suppression in MLC was not observed until lymphocytes were pretreated for 48 h. These studies support the previous observations that OKT3 may be reacting with an important molecule on the T cell surface and that interaction of OKT3 with this molecule induces profound functional changes.

Maturation of sympathetic neurotransmission in the rat heart. VII. Suppression of sympathetic responses by dexamethasone

Effects of dexamethasone on development of sympathetic nerve function in the heart were evaluated by giving 1 mg/kg of dexamethasone s.c. daily for several days beginning the day after birth. Dexamethasone interfered with tyramine- and isoproterenol-induced tachycardia in the neonates but did not cause alterations in development of a marker for presynaptic sympathetic nerve terminals (synaptic vesicle uptake of [3H] norepinephrine) nor of postsynaptic beta adrenoceptor binding of [3H]dihydroalprenolol; the deficit was also unrelated to general cellular effects of the hormone. These data suggest that the subnormal chronotropic responses of the heart to sympathetic stimulation in dexamethasone-treated neonatal rats result from uncoupling of receptors from the organ response. The effects of dexamethasone on cardiac responses were specific to the neonate, as mature rats given dexamethasone did not show suppression of cardiac sympathetic action. Neonatal dexamethasone treatment also produced a deficit of adrenomedullary development with deficiencies in catecholamine levels and in catecholamine biosynthetic enzymes; deficits in phenylethanolamine N-methyltransferase activity persisted into young adulthood.