Biomedical subjects
Publications and source records attributed to N Greenberg.
Familial congenital pyloric atresia is a rare malformation of the fetal gastrointestinal tract. It usually manifests as maternal polyhydramnios and enlarged fetal stomach on ultrasound scan. Sonographic prenatal diagnosis and management of a pregnancy complicated by familial congenital pyloric atresia are presented.
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Three interlaboratory round-robin studies (RR1, RR2, and RR3) were conducted to identify a serum-based reference material that would aid in the standardization of direct ion-selective electrode (ISE) measurements of sodium and potassium. Ultrafiltered frozen serum reference materials requiring no reconstitution reduced between-laboratory variability (the largest source of imprecision) more than did other reference materials. ISE values for RR3 were normalized by the use of two points at the extremes of the clinical range for sodium (i.e., 120 and 160 mmol/L), with values assigned by the flame atomic emission spectrometry (FAES) Reference Method. This FAES normalization of ISE raw values remarkably improved all sources of variability and unified the results from seven different direct ISE analyzers to the FAES Reference Method value. Subsequently, a three-tiered, fresh-frozen human serum reference material was produced to the specifications developed in RR1-RR3, was assigned certified values for sodium and potassium by Definitive Methods at the National Institute of Standards and Technology (NIST), and was made available in 1990 to the clinical laboratory community as a Standard Reference Material (SRM); it is now identified as SRM 956. Albeit retrospectively, we show how applying an FAES normalization step identical to that used in RR4/5 to the ISE data for SRM 956 after the NIST Definitive Method values were known, consistently moved the ISE results for RR3 closer to the true value for Na+ and K+.
It is well known that androgen-dependent sexual behaviors in male mammals and birds are inhibited by exogenous progesterone (P). However, recent research on male whiptail lizards (Cnemidophorus inornatus) indicates that P can stimulate sexual and copulatory behavior. We report here both antiandrogenic and synandrogenic actions of P on sexual behavior in males of another reptile, the green anole lizard (Anolis carolinensis). Earlier reports on birds and mammals are reviewed and discussed in relation to a possible physiological role of P in influencing sexual behavior in male vertebrates.
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Adult males of the small arboreal iguanid lizard, Anolis carolinensis, will fight and form social dominance hierarchies when placed in habitats with limited resources. The relationships between time since initial aggressive interaction, relative social dominance, reproductive activity, and corticosterone and androgen levels were determined for 34 pairs of lizards. A discriminant analysis established a "dominance index" which indicated that over 90% of the difference between individuals who had won or lost aggressive interactions (putative social dominants and subordinates) was attributable to a single discriminant function reflecting altered body color, perch site selection, and circulating androgen. Animals that had darker body color also selected lower perch sites and had depressed rates of courtship relative to winners of fights and were thus designated as social subordinates. These animals also had levels of circulating androgen significantly lower than that of dominants, but circulating corticosterone was not significantly affected. Winners of fights showed a dramatic surge in circulating androgen at 1 hr but returned to near control values by 1 week; losers, however, showed depressed circulating androgen levels at 1 week.
We examined the influences of territorial status, encounter outcome, body mass difference, activity, and display on lactate accumulation in adult male Anolis carolinensis during agonistic interactions. Of the pairs of lizards frozen at the onset of an encounter, intruders had significantly higher lactate concentrations than residents. Lactate levels at the onset of an interaction were not significantly different from those at the conclusion, suggesting a limited role for glycolysis during such events. The outcome of an agonistic encounter was not based on fatigue. Individuals that were larger or changed sites had a lower relative lactate concentration at the conclusion of an interaction than smaller or sedentary animals. We consider the influence of autonomic arousal on glycolysis.
Persons who received measles vaccine between 12 and 14 months of age have been found to be at increased risk of measles compared with those vaccinated at greater than or equal to 15 months of age. Because of this, in 1987 the Immunization Practices Advisory Committee of the US Public Health Service recommended that, during measles outbreaks, revaccination of persons vaccinated at 12-14 months of age be considered. During a school-based outbreak in New Mexico in 1987, the authors evaluated the effect of a mandatory revaccination policy in affected schools. Before the effect of revaccination, the overall attack rate in persons vaccinated at greater than or equal to 12 months of age was 4.1 cases/1,000 students; afterward, the risk was significantly reduced by 73%, to 1.1/1,000 students. The attack rate among students targeted for revaccination declined 100%, compared with 41% among those not revaccinated. Overall, attack rates were significantly lower in schools conducting revaccination early compared with schools holding later revaccination. In a retrospective cohort study of single-dose vaccines in one school, age at vaccination was not associated with risk of disease; however, persons vaccinated greater than or equal to 10 years before the outbreak were at increased risk, independently of age at vaccination. Revaccination of persons whose most recent vaccination was between 12 and 14 months of age appeared to control transmission in this outbreak. Further studies are needed to confirm these observations and to evaluate the effect of other revaccination efforts during outbreaks.
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Lacking sympathetic innervation, the skin of A. carolinensis, an iguanid lizard, darkens within minutes in response to circulating melanocyte stimulating hormone (MSH) or beta adrenergic agonists such as epinephrine (EPI). This change is produced by dispersion of melanin from a perinculear position within dermal melanophores into superficial dendritic processes. These melanophores possess alpha-2 and beta-2 adrenergic as well as MSH receptors except in a patch of skin behind the eye, the eyespot, which lacks alpha receptors. Activation of beta or MSH receptors leads to stimulation of adenyl cyclase whereas alpha stimulation inhibits the enzyme to override the others. In a series of trials, injection of saline or propranolol was followed after 30 minutes by saline, EPI, or MSH. Propranolol inhibited chromatophore response to EPI. It also, unexpectedly, retarded the response to MSH, increasing latency to eyespot formation and body color change as well as the duration of darkening for both. Alteration of MSH response by a beta blocker could be explained by linkage of both adrenergic receptors and the MSH receptor to a common adenyl cyclase molecule to form a functional unit in the membrane of the melanophore.
The deoxypyrimidine nucleoside analog 2'-fluoro-2'-deoxy-1-beta-D-arabinofuranosyl-5-iodocytosine (FIAC) is a potent and selective inhibitor of herpes simplex virus type 1 in vitro (C. Lopez, K. A. Watanabe, and J. J. Fox, Antimicrob. Agents Chemother. 17:803-806, 1980). Isopycnographic analysis demonstrated that 1 microM FIAC inhibited herpes simplex virus DNA replication by more than 95% but inhibited cellular DNA replication by only 32%. Mutant herpes simplex virus type 1 selected resistant to FIAC displayed linked resistance to other nucleoside analogs, including arabinosylthymine and acyclovir. Lysates derived from Vero cells infected with FIAC-resistant virus showed markedly lower levels of thymidine kinase activity and were unable to phosphorylate selectively arabinosylthymine or FIAC, in contrast to lysates from cells infected with wild-type herpes simplex virus type 1. Finally, drug-resistant virus displayed a 6,000-fold decrease in pathogenicity when inoculated intraperitoneally into genetically susceptible A/J mice. These results indicate that resistance to deoxypyrimidine nucleoside analogs is due, at least in part, to alterations in viral thymidine kinase and is accompanied by decreased pathogenicity in vivo.
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Platelet activating factor (PAF) and 1-O-alkyl-linked choline-containing phosphoglycerides have been identified in the blood of the lizard, Anolis carolinensis. The level of PAF in the blood of chronically stressed lizards is 250% higher than in that of controls; the blood contains sufficient 1-O-alkyl-linked choline-containing phosphoglycerides to support the synthesis of PAF. Incorporation of PAF is higher in the liver than in the blood; control animals incorporate more PAF than chronically stressed animals. "Lyso"-PAF is the major metabolite in the blood; whereas, in the liver both "lyso"-PAF and "acyl"-PAF are predominant products. 1-Alkyl-2-acetyl-sn-glycero-3-phosphocholine:acetylhydrolase activity in the chronically stressed or corticosterone-implanted lizards is increased 2- to 3-fold over the control. Involvement of PAF in the physiological response to psychological stress is indicated.
Adult males of the small arboreal iguanid lizard, Anolis carolinensis, form social dominance hierarchies when placed in habitats with limited resources. Skin color changes occur during hierarchy formation, most conspicuously in subordinates, who appear darker (more brown) than dominants (more green). Because skin color in this species is under the control of hormones frequently associated with physiological stress, radioimmunoassay of plasma levels of the principal reptilian adrenal steroid, corticosterone, was performed. To examine the influence of gonadal androgen, known to influence the aggression that attends hierarchy formation, lizard pairs were constituted in which one or both members were castrated. Corticosterone levels of intact subordinates were significantly elevated, whereas those of castrated subordinates or dominants showed levels comparable to those of isolates. No significant differences in spermatogenic stage could be detected between intact dominants or subordinates.
Thirteen male green anole lizards were lesioned in the ventromedial nucleus (VMN) of the posterior dorsal ventricular ridge ("amygdala") and/or the paleostriatum (PS) to determine the influence of these structures on assertion and challenge displays addressed to male intruders, or courtship displays and copulatory neckgrip directed toward females. Lesions that affected both VMN and PS reduced or eliminated both challenge and courtship displays as well as the neckgrip, a crucial component in courtship. Subjects with lesions limited to VMN had assertion and challenge left unimpaired but courtship was reduced and neckgrip eliminated in most subjects. A lesion restricted to PS caused a significant deficit in challenge while other measures were unaffected. These data indicate that the VMN is involved in reproductive function in the green anole lizard.
Synthesis of 1-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)uracils containing a vinyl (4a), 2-halovinyl (4b-d), or ethyl substituent at C-5 was achieved. These nucleosides were found to be about a log order less active than 2'-fluoro-5-iodo-ara-C (FIAC) against HSV-1, but they are much less cytotoxic against normal human lymphocytes than FIAC. Nucleosides 4a and 4e showed good activity against HSV-1 (ED50 = 0.16 and 0.24 microM, respectively) and HSV-2 (ED50 = 0.69 and 0.65 microM) with very little cytotoxicity (ID50 greater than 100 microM).
A physical map of L-2 DNA was constructed using restriction endonucleases. Based on this map the five HincII-generated L-2 DNA fragments (A-E) were cloned into the SmaI site of Escherichia coli vector plasmid pOL4, that was designed to analyze promoters and transcriptional terminators. The insertion of the HincII-generated L-2 DNA fragments into this plasmid clearly demonstrated that a fragment (fragment E) with a size of 1.1 kbp carried a sequence that initiated transcription in E. coli.
A large measles vaccination program in the Albuquerque, New Mexico public schools in 1981, conducted according to US Public Health Service guidelines, was studied to determine rates of pregnancy among adolescent vaccinees. Pre-vaccination counseling of 1,922 clinic attendees prevented seven pregnant girls from being vaccinated. Despite counseling, of 1,913 female vaccinees age 13-18 years old, two were pregnant at the time of vaccination (1.05 pregnancies per 1,000 vaccinees) and an additional four girls became pregnant in the three months after vaccination (2.1 pregnancies per 1,000 vaccinees). Data supporting low or absent fetal risks from measles and rubella vaccine, combined with the low pregnancy rate among vaccinees documented in this study, support the reasonableness of the recommended strategy for measles and rubella vaccination of secondary schoolgirls.