Glucocorticoid effects on phenylethanolamine N-methyltransferase (PNMT) in explants of embryonic rat medulla oblongata

Although glucocorticoid hormones have important roles in the development of neurotransmitter systems in cells derived from the neural crest, it is not known whether they have parallel effects on neuronal development in the brain. To address this issue, we have established an in vitro system of fetal medulla oblongata (MO) to follow development of the epinephrine-synthesizing enzyme, phenylethanolamine N-methyltransferase (PNMT). Embryonic MO was explanted from E13 or E18 embryos and maintained for up to 3 weeks. Successful culture of adrenergic neurons was possible only in explants taken from young embryos, since E18 explants failed to develop. In E13 explants, immunoreactivity to both PNMT and tyrosine hydroxylase, the rate limiting enzyme in catecholamine synthesis, was observed. PNMT catalytic activity which was barely detectable at the time of explanation increased markedly during the first week in vitro. To study the effects of glucocorticoids on PNMT development in central neurons, MO explants were grown in glucocorticoid deficient medium in which rat serum from adrenalectomized rats was substituted for human placental serum. Addition of natural glucocorticoids, cortisol or corticosterone, or the mineralcorticoid, deoxycorticosterone, during the third culture week had no effect on PNMT activity. Dexamethasone (DEX), a synthetic glucocorticoid, also had no effect on PNMT during the first or second weeks in culture. However, addition of DEX during the third culture week resulted in a doubling of PNMT activity. However, attempts to block the DEX effect during the third week or to block the increase in PNMT activity during the first week in control cultures with the glucocorticoid receptor antagonist, dexamethasone 21-mesylate, were unsuccessful. These results suggest that PNMT in central neurons does not require glucocorticoids for ontogeny during the embryonic period. This is in contrast to PNMT in adrenal medulla which requires glucocorticoids for normal development during both the embryonic and postnatal periods. More generally, these studies suggest that development of the same neurotransmitter phenotype in brain and periphery may be differentially regulated.     

Non-clastogenicity in mouse bone marrow of fructose/lysine and other sugar/amino acid browning products with in vitro genotoxicity

Heated sugar/amino acid reaction mixtures, known to contain products that are clastogenic and/or mutagenic to cells in vitro, were evaluated for clastogenic activity in mouse bone marrow using the erythrocyte micronucleus assay. Heated (i.e. browned) fructose/lysine reaction mixtures were also evaluated in the Salmonella his-reversion assay and the Chinese hamster ovary (CHO) cell chromosomal aberration assay to confirm and extend previous in vitro observations. Significant mutagenicity of fructose/lysine mixtures was observed in Salmonella typhimurium strains TA100, TA2637, TA98 and TA102, with greater activity in mixtures heated at pH 10 than at pH 7. S-9 decreased the activity in strains TA100, TA2637 and TA98, but increased the activity in strain TA102. Both pH 7 and pH 10 reaction mixtures of the fructose/lysine browning reaction were highly clastogenic in CHO cells. Heated mixtures of fructose and lysine, and of glucose or ribose with lysine, histidine, tryptophan or cysteine, did not increase the frequency of micronucleated erythrocytes in mice when administered by the oral route. This indicates the absence of chromosomal aberrations in erythrocyte precursor cells, and indicates that the genotoxic components of the browned mixtures are not absorbed and distributed to bone marrow cells in amounts sufficient to induce micronuclei when given orally. Because sugar/amino acid browning reactions occur commonly in heated foods, it is important to evaluate further the in vivo genotoxicity of browning products in cell populations other than bone marrow.     

Susceptibility of Nd:YAG laser-irradiated root surfaces in replanted teeth to external inflammatory resorption

Abstract— NdYAG laser-induced modification of the root surface may inhibit development of external inflammatory resorption in replanted teeth. This study tested this hypothesis in vivo. The pulp chambers of six mandibular premolars in each of two dogs were accessed, inoculated with plaque, and sealed (Groups 1, 2). Two additional premolars in each dog were endodontically treated without inoculation (Groups 3, 4). After 2 weeks, teeth were hemisected and extracted. Each root had a 2times3 mm surface area denuded of cementum on the buccal and lingual surface. In Groups 1 (n= 12 roots) and 3 (n=4), the denuded surfaces were wiped with 15% EDTA, coated with black ink, and irradiated with Nd:YAG laser (0.75 W, 15 ppc, 300 pm tip, 20 s). In Groups 2 (n= 12) and 4 (n= 4), the surfaces were wiped with 15% EDTA, and rinsed with sterile saline for 20 s. Roots were replanted within 5 min. The dogs were perfwion-euthanised 10 weeks after replantation. Block specimens were removed, decalcified, embedded and horizontally sectioned (6 pm) at 180-pm intervals, resulting in 10 to 14 cross-sections of each root. From these, the middle five consecutive sections were stained with hematoxylin and eosin, and observed by light microscopy for occurrence of surface, inflammatory and replacement resorption on the denuded surfaces. No obvious differences were noted between the laser-irradiated and non-irradiated surfaces. Inflammatory resorption was frequent in Groups 1 and 2, and absent in Groups 3 and 4. Replacement resorption was minimal in Groups 1 and 2, and frequent in Groups 3 and 4. Differences between Groups 1 and 2, and between Groups 3 and 4 were not significant, whereas the differences between the two pairs of groups were statistically significant (chi-square and two-way ANOVA, P>0.006). These results did not support the hypothesis, and questioned the clinical validity of the surface modification in NdYAG laser-irradiated den-tin. Therefore, the clinical application of NdYAG laser to the root surfaces of replanted teeth is not warranted.     

Geriatric diabetic nephropathy: an analysis of renal referral in patients age 60 or older

We report a series of 33 consecutive hospitalized geriatric diabetic patients who were referred for evaluation of diabetic nephropathy, defined as proteinuria greater than or equal to 1 g/d (1,000 mg/24 h) or a serum creatinine concentration greater than or equal to 177 mumol/d (greater than or equal to 2 mg/dL). The study population was 60 years old or older (mean age, 68 +/- 6 years), was comprised mainly of women (24 of 33, 72.7%), and was predominantly black (25 of 33, 75.8%). All patients had type II diabetes. A family history of diabetes in parent or sibling was elicited in 24 (72.7%) patients. There were eight patients undergoing maintenance hemodialysis and 25 with less severe nephropathy (mean proteinuria, 2.7 g/d [2,700 mg/24 h]; mean creatinine clearance, 0.57 mL-s [34 mL/min]). Cardiac disorders were noted in the majority of patients: congestive failure in 20 (60.6%), myocardial infarction in eight (24.2%), and active angina in five (15.2%). Other comorbid diseases were present in both hemodialysis patients and the subset of nondialyzed azotemic-proteinuric patients, and consisted of peripheral neuropathy in 31 (93.9%), gastroparesis in 16 (48.5%), retinopathy in 28 (84.8%), and legal blindness in 11 (33%). We conclude that geriatric diabetic nephropathy in type II diabetes is similar in presentation and severity of comorbid extrarenal complications to the syndrome described in younger adults. This inference must be tempered by both the small size and the limitation imposed by the demographics of the study population, which is predominantly composed of black patients receiving treatment at inner city hospitals.     

Clinical findings and common symptoms in retinitis pigmentosa

Data analysis was performed in a prospective study of clinical symptoms and findings in 500 patients with retinitis pigmentosa. The symptoms and findings in these patients met the usual definitions of the disease. At initial examination the patients were questioned in a standardized manner; symptoms and associated health problems were reviewed. Some patients were unable to answer all of the questions. Of the patients 274 (55%) were men and 226 (45%) were women, with a race distribution of 21 (4%) black, 47 (9%) Hispanic, 26 (5%) Oriental, three (1%) American Indian, and 403 (81%) white. Sixty-nine patients reported no symptoms of night blindness and 116 patients claimed no visual field changes; 90 stated that they saw better at dusk. The most common problem noted by 263 (53.3%) was headaches, 31 on a daily basis, 42 at least weekly, 124 infrequently, and the remainder nonspecifically. Numbness or tingling, mainly in extremities, was reported by 99 patients. The second most common problem affecting 170 patients (34.6%) was light flashes; since eight patients had retinal detachments, light flashes cannot be totally discounted. Of 143 patients who had been pregnant, 14 had visual changes.     

The tarsal pillar technique for narrowing and maintenance of the interpalpebral fissure.

We describe a tarsorrhaphy technique whereby an ipsilateral upper-eyelid tarsal pillar is sutured to a corresponding lower-eyelid recipient site. This technique allows maintenance of a narrowed interpalpebral fissure indefinitely, yet is easy to reverse without incurring lid-margin damage. Additionally, the procedure can be adjusted postoperatively to either narrow or widen the initial surgical result. We report our combined surgical experience in 35 consecutive procedures using this technique to treat eyes with exposure-related keratopathy of varied etiology, including facial nerve palsies, combined facial nerve palsy and trigeminal neuropathy with an anesthetic cornea, Graves' disease, congenital craniofacial anomalies, and severe keratitis sicca syndrome. The procedure was successful in improving exposure keratopathy symptoms in all 35 cases. Complications, reflecting the authors' learning curve with this new procedure, included intermarginal pyogenic granulomas, stretching of the tarsal pillar, minor lower-eyelid-margin eversion, and tarsal pillar dehiscence.     

Contrasting Effects of thc on Adult Murine Lymph Node and Spleen Cell Populations Stimulated with Mitogen or Anti-CD3 Antibody

Marijuana, and specifically its psychoactive component, THC, can up or down regulate lymphocyte proliferation in murine spleen cells depending in part on the method used to stimulate the cells. This study identifies a difference in THC induced disregulation using cells derived from two different secondary lymphoid organs, the spleen and the lymph node. It was found that THC treatment of mitogen (concanavalin A or phytohemagglutinin) stimulated cells derived from either organ resulted in suppression of the proliferative response. In contrast, spleen cells stimulated with anti-CD3 antibody and treated with low doses of THC displayed an enhanced proliferation whereas the response in lymph nodes did not change. The cell type involved with this THC immunoenhancement in spleen cells was found to be the Ly2 cell. Further differences in the THC modulation of Ly2 spleen cells as compared to lymph node cells were noted following stimulation with PHA. Proliferation of Ly2 cells of splenic origin was inhibited with low doses of THC whereas the Ly2 cells of lymph node origin were more resistant to this drug induced suppression. This study, therefore, demonstrates differences in the immunomodulatory capability of THC dependent upon the organ source of the lymphocytes.