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Biomedical subjects

M S Gray

Publications and source records attributed to M S Gray.

13 recordsLinked to original sources
PubMed1999

Dissimilatory reduction of Fe(III) and other electron acceptors by a Thermus isolate.

A thermophilic bacterium that can use O2, NO3-, Fe(III), and S0 as terminal electron acceptors for growth was isolated from groundwater sampled at a 3.2-km depth in a South African gold mine. This organism, designated SA-01, clustered most closely with members of the genus Thermus, as determined by 16S rRNA gene (rDNA) sequence analysis. The 16S rDNA sequence of SA-01 was >98% similar to that of Thermus strain NMX2 A.1, which was previously isolated by other investigators from a thermal spring in New Mexico. Strain NMX2 A.1 was also able to reduce Fe(III) and other electron acceptors. Neither SA-01 nor NMX2 A.1 grew fermentatively, i.e., addition of an external electron acceptor was required for anaerobic growth. Thermus strain SA-01 reduced soluble Fe(III) complexed with citrate or nitrilotriacetic acid (NTA); however, it could reduce only relatively small quantities (0.5 mM) of hydrous ferric oxide except when the humic acid analog 2,6-anthraquinone disulfonate was added as an electron shuttle, in which case 10 mM Fe(III) was reduced. Fe(III)-NTA was reduced quantitatively to Fe(II); reduction of Fe(III)-NTA was coupled to the oxidation of lactate and supported growth through three consecutive transfers. Suspensions of Thermus strain SA-01 cells also reduced Mn(IV), Co(III)-EDTA, Cr(VI), and U(VI). Mn(IV)-oxide was reduced in the presence of either lactate or H2. Both strains were also able to mineralize NTA to CO2 and to couple its oxidation to Fe(III) reduction and growth. The optimum temperature for growth and Fe(III) reduction by Thermus strains SA-01 and NMX2 A.1 is approximately 65 degrees C; their optimum pH is 6.5 to 7.0. This is the first report of a Thermus sp. being able to couple the oxidation of organic compounds to the reduction of Fe, Mn, or S.

Biodegradation, Environmental↗
PubMed1992

The effects of cocaine on maternal behaviors in the rat.

Although recent research has focused on the behavioral teratology of cocaine, there has been little attention centered on the effects of cocaine use on parenting behaviors after birth. This experiment investigated the effects of cocaine on parental (generally termed maternal) behavior in the rat. Four types of adult rats were tested for these effects over a 10-day testing period: lactating primiparous female dams, primiparous females, nulliparous females, and males. Subjects were injected daily with cocaine (5 mg/kg) or saline. Ten minutes postinjection each subject was placed in a cage with three stimulus pups and nesting material, and observed for several measures of maternal behavior for 5 minutes, including sniffing, licking, and retrieving pups. Subjects were also rated on a maternal behavior scale at 60 minutes and 24 hours postinjection, and on nest quality. Cocaine reduced both the total number and duration of sniffing and licking maternal behaviors, and resulted in a lower maternal behavior rating at 60 minutes compared to saline-treated subjects. Among those subjects that retrieved pups within the first 5 minutes, cocaine-injected subjects retrieved for a longer duration. These results also suggest impaired maternal behavior, since rapid retrievals would have been more efficient in maintaining a nest huddle. Thus, cocaine impaired the parenting ability of both male and female rats, with and without previous parenting experience.

Animals↗
PubMed1991

Renal nerves modulate renin gene expression in the developing rat kidney with ureteral obstruction.

Chronic unilateral ureteral obstruction (UUO) in newborn rats activates renin gene expression in the obstructed kidney, and increases renin distribution along afferent glomerular arterioles in both kidneys. To investigate the role of the renal nerves in this response, 2-d-old Sprague-Dawley rats were subjected to UUO or sham operation. Chemical sympathectomy was performed by injection of guanethidine, whereas, control groups received saline vehicle. At 4-5 wk, renal renin distribution was determined by immunocytochemistry, and renin mRNA levels were determined by Northern blot hybridization. Compared to the saline-treated rats with UUO, renin remained localized to the juxtaglomerular region in both kidneys of rats with UUO receiving guanethidine (P less than 0.05). Moreover, renin mRNA levels were eightfold lower in obstructed kidneys of rats receiving guanethidine than in those receiving saline. Additional groups of rats with UUO were subjected to unilateral mechanical renal denervation: renin gene expression in the obstructed kidney was suppressed by ipsilateral but not by contralateral renal denervation. These findings indicate that either chemical or mechanical denervation suppressed the increase in renin gene expression of the neonatal kidney with ipsilateral UUO. We conclude that the renal sympathetic nerves modulate renin gene expression in the developing kidney with chronic UUO.

Animals↗
PubMed1990

In situ localization of renin and its mRNA in neonatal ureteral obstruction.

Angiotensin II is an important mediator of renal vasoconstriction resulting from chronic unilateral ureteral obstruction (UUO). Distribution of renin mRNA and immunoreactive renin (IR) was examined in kidneys of 1-mo-old Sprague-Dawley rats subjected to either sham operation (n = 21), left complete UUO (n = 21), or right uninephrectomy (UNX, n = 16) at 2 days of age. There were no differences among the three groups in mean arterial pressure or plasma renin activity. Unlike sham kidneys, in which IR was detected in less than 55% of juxtaglomerular apparatuses (JGA) and was confined to a juxtaglomerular location, IR in both kidneys of animals with UUO appeared in greater than 75% of JGA and extended along most of the length of the afferent arteriole (P less than 0.01). In contrast, IR in kidneys of UNX rats was localized to the JGA as in sham-operated animals. Compared with sham-operated kidneys, renal renin content was increased in the obstructed kidneys (P less than 0.01) but decreased in the intact opposite kidneys of UUO rats and in the remaining kidneys of UNX rats (P less than 0.05). Renin mRNA, detected by in situ hybridization histochemistry, was localized to the JGA in kidneys of all groups. However, the fraction of JGA containing detectable renin mRNA was higher in obstructed kidneys than in intact opposite, UNX, or sham kidneys (P less than 0.05). In conclusion, UUO alters intrarenal renin independent of the systemic renin-angiotensin system. The greater distribution of IR, increased renin content, and renin gene expression of kidneys with ipsilateral UUO are consistent with a role for renin-angiotensin in mediating the vasoconstriction resulting from UUO.

Animals↗
PubMed1989

Association of 3'----5' exodeoxyribonuclease activity with DNA replitase complex from S-phase Chinese hamster embryo fibroblast cells.

DNA replitase has been described as a complex of enzymes/proteins that are associated with both DNA precursor biosynthesis and DNA replication in mammalian cells [Reddy, G. P. V., and Pardee, A. B. (1980) Proc. Natl. Acad. Sci. USA 77, 3312-3316]. We demonstrate for the first time a 3'----5' exodeoxyribonuclease activity is associated with the replitase complex. As much as 60% of this exonuclease activity was similar to that associated with DNA polymerase delta based upon its sensitivity to inhibition by GMP and by butyl-phenyl-deoxyguanosine triphosphate (BuPdGTP). Association of 3'----5' exonuclease activity with the DNA polymerase in the replitase complex was also demonstrated by analyzing dTTP turnover to dTMP in an in vitro DNA polymerase assay system. The DNA polymerase activity in replitase complex exhibited a sensitivity to BuPdGTP which both was similar to that of DNA replication in permeable cells and was intermediate between the BuPdGTP inhibition of purified DNA polymerases alpha and delta. These studies suggest that the replitase complex contains 3'----5' exonuclease activity associated with the DNA polymerase activity responsible for nuclear DNA replication in mammalian cells. Further studies are required to determine if these activities are at least partially attributed to DNA polymerase delta.

Animals↗
PubMed1988

Certification: serving the public interest.

The certification program has undergone an exciting change. The AOTA leadership and AOTA members are to be applauded for making this important step. The AOTCB is still a fledgling organization; nonetheless, it has already made great strides in carrying out its mission. The AOTCB will continue to build on the very excellent foundation AOTA has laid for the certification program. The AOTCB welcomes questions, comments, and suggestions concerning the certification program. To contact AOTCB, write to AOTCB, 1383 Piccard Drive, Rockville, MD 20850-4375 or call (301) 948-9626.

Certification↗
PubMed1984

Recertification and relicensure in the allied health professions.

This article identifies and clarifies some of the major issues concerning recertification and relicensure of allied health practitioners. Various methods of recredentialing are discussed; while mandatory continuing education may not provide evidence of competency, it may be more acceptable to health care practitioners than any other type of requirement. However, statewide peer review/audit, on-the-job performance evaluation, and a national written examination may be more suitable as recredentialing methods if certain conditions are met. Criteria are suggested for the evaluation of any proposed recredentialing program; for example, the program should be criterion-referenced based, valid, reliable, accessible, cost-effective, and acceptable. If such a recredentialing program is developed, the credentialing board and the practitioners--and ultimately employers, third-party payers, and consumers--must bear the additional costs. The major questions are "Is it necessary?" and "Is it worth it?"

Allied Health Personnel↗
PubMedDate not supplied

Reliable disparity estimation through selective integration.

A network model of disparity estimation was developed based on disparity-selective neurons, such as those found in the early stages of processing in the visual cortex. The model accurately estimated multiple disparities in regions, which may be caused by transparency or occlusion. The selective integration of reliable local estimates enabled the network to generate accurate disparity estimates on normal and transparent random-dot stereograms. The model was consistent with human psychophysical results on the effects of spatial-frequency filtering on disparity sensitivity. The responses of neurons in macaque area V2 to random-dot stereograms are consistent with the prediction of the model that a subset of neurons responsible for disparity selection should be sensitive to disparity gradients.

Animals↗
PubMedDate not supplied

Intranasal butorphanol-induced apraxia reversed by naloxone.

Intranasal butorphanol is an opioid agonist-antagonist that is effective for the treatment of acute pain. Common adverse effects associated with the agent are somnolence, dizziness, nausea, and vomiting; they are readily reversed with naloxone. A patient developed signs and symptoms consistent with apraxia after a single dose of intranasal butorphanol. She was mentally alert, but she was unable to move or speak despite normal muscle tone and reflex movements. When she attempted to speak she had no voluntary control. At the emergency room she was administered naloxone 2 mg intramuscularly, which resulted in complete reversal of the symptoms in a short time. No other published cases describe these findings with butorphanol. Health care professionals should be aware that patients who are prescribed intranasal butorphanol, even in typical doses, may be at risk for such a reaction. This is important because, unlike the injectable formulation, the intranasal product is primarily used in the outpatient setting.

Administration, Intranasal↗