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Biomedical subjects

J A Carson

Publications and source records attributed to J A Carson.

At least 37 records · Page 2Linked to original sources
PubMed1997

Myogenic regulatory factors during regeneration of skeletal muscle in young, adult, and old rats.

Myogenic factor mRNA expression was examined during muscle regeneration after bupivacaine injection in Fischer 344/Brown Norway F1 rats aged 3, 18, and 31 mo of age (young, adult, and old, respectively). Mass of the tibialis anterior muscle in the young rats had recovered to control values by 21 days postbupivacaine injection but in adult and old rats remained 40% less than that of contralateral controls at 21 and 28 days of recovery. During muscle regeneration, myogenin mRNA was significantly increased in muscles of young, adult, and old rats 5 days after bupivacaine injection. Subsequently, myogenin mRNA levels in young rat muscle decreased to postinjection control values by day 21 but did not return to control values in 28-day regenerating muscles of adult and old rats. The expression of MyoD mRNA was also increased in muscles at day 5 of regeneration in young, adult, and old rats, decreased to control levels by day 14 in young and adult rats, and remained elevated in the old rats for 28 days. In summary, either a diminished ability to downregulate myogenin and MyoD mRNAs in regenerating muscle occurs in old rat muscles, or the continuing myogenic effort includes elevated expression of these mRNAs.

Aging↗
PubMed1996

Stretch overload-induced satellite cell activation in slow tonic muscle from adult and aged Japanese quail.

Stretch overload-induced activation of satellite cells in the anterior latissimus dorsi (ALD) muscle was examined in full-grown adult (12 wk old) and aged (90 wk old) Japanese quail. 5'-Bromo-2'-deoxyuridine (BrdU) constant-release pellets (0.22 mg BrdU.g body wt-1.day-1) were implanted subcutaneously before weighting the left wing of each bird. Nuclei that incorporated BrdU were localized by immunohistochemistry after 1 or 2 wk of stretch overload. Total fiber number was quantified by counting all fibers in a histological cross section from the midbelly of the ALD. Aging reduced increases in ALD mass and fiber number during 2 wk of stretch overload. Fiber proliferation in the ALD of aged birds also demonstrated an altered time course. The percentage of BrdU-positive nuclei associated with muscle fibers and the percentage of fibers associated with BrdU-positive nuclei did not differ between age groups. The altered time course of new fiber formation in the ALD of aged birds during 2 wk of stretch overload does not appear to be related to the capability to activate satellite cells.

Aging↗
PubMed1996

SRF and TEF-1 control of chicken skeletal alpha-actin gene during slow-muscle hypertrophy.

The purpose of this study was to delineate the alpha-actin regulatory elements and transcription factors that are responsible for conferring stretch-overload responsiveness during hypertrophy of the anterior latissimus dorsi (ALD) muscle of young chickens by weighting one wing. Minimal promoter constructs were evaluated by direct injection into the ALD, which demonstrated that both serum response element 1 (SRE1) and the transcriptional enhancer factor 1 (TEF-1) elements were sufficient for increased expression during stretch overload. A mutated SRE1 prevented expression in both basal and stretched ALD muscles, whereas a mutated TEF-1 element reduced actin promoter function in both control and stretched muscles. The serum response factor (SRF)-SRE1 binding complex demonstrated faster migration in mobility shift assays from day 3-and day 6-stretched ALD nuclear extracts relative to their control. TEF-1 binding was qualitatively increased in stretched extracts at day 3 but not day 6 of stretch overload. Skeletal alpha-actin mRNA accumulated from day 3 to day 6 of stretch overload. These data demonstrate that SRE1 is necessary and sufficient for stretch-overload responsiveness from the skeletal alpha-actin promoter and that the SRF-SRE1 binding complex migrates faster in stretched nuclear extracts of hypertrophied relative to control extracts from intact ALD muscles of chickens.

Actins↗
PubMed1995

Adaptation in myosin expression of avian skeletal muscle after weighting and unweighting.

Stretch-induced hypertrophy of the quail anterior latissimus dorsi is associated with decreased slow myosin 1 and increased slow myosin 2 expression and a small increase in expression of fast myosins. Because reduced neural activity has also been shown to accelerate expression from slow myosin 1 to slow myosin 2, we tested whether the increased expression of slow myosin 2 would be maintained when stretch was removed during a time when muscle activity would not be expected to increase. Quail anterior latissimus dorsi muscles were examined after 0-30 days of stretch overload and after 30 or 60 days of unweighting following 30 days of stretch. As expected, slow myosin 2 expression increased and slow myosin 1 expression decreased after 14-30 days of stretch. Novel findings were that slow myosin 1 and slow myosin 2 returned to control levels after unweighting. Furthermore, the expression of developmental and fast myosin heavy chains were evident by day 7, and maintained throughout wing unweighting. These data are consistent with the hypothesis that alterations in fast and developmental myosin expression result from formation and subsequent maintenance of new fibres during hypertrophy and regression. The relative amount and expression of myosin appears dependent upon mechanical stretch in the anterior latissimus dorsi muscle.

Adaptation, Physiological↗
PubMed1995

Time course of hypertrophic adaptations of the anterior latissimus dorsi muscle to stretch overload in aged Japanese quail.

The purpose of this study was to determine if aged Japanese quail demonstrated an altered time course of change in the morphology of the anterior latissimus dorsi (ALD) muscle during the first two weeks of hypertrophy induced by stretch overload. The left wing of adult (12 weeks of age) and aged (90 weeks of age) birds were weighted with 10% of their body weight; the right wing served as the intra-animal control. Thirteen to sixteen birds from each age group were killed after 7 and 14 days of stretch overload. Total fiber number was quantified by counting all the fibers in a transverse section from the mid-belly of the ALD muscle. The aged ALD retained the ability to increase the mass and total fiber number of the stretched ALD after 7 (82%, 16%) and 14 (102%, 19%) days of stretch overload. However, there was a main effect of age on the capacity to increase muscle mass and total fiber number after stretch overload. These results suggest that aging diminishes the increase and alters the time course of adaptation in fiber number and myofibrillar mass of the stretch overloaded ALD during the first two weeks of stretch overload.

Adaptation, Physiological↗
PubMed1995

Regulation of skeletal alpha-actin promoter in young chickens during hypertrophy caused by stretch overload.

Anterior latissimus dorsi (ALD) muscles of 3-wk-old male chickens were injected with plasmids containing various lengths of the chicken skeletal alpha-actin promoter (ranging from -2,090 to -77 relative to the transcription start site) driving luciferase. Hypertrophy of the left ALD muscle was induced by attaching a weight (11% of body wt) to the left wing of each chicken, with the unweighted contralateral wing serving the control. Six days of stretch overload significantly increased muscle mass 110%. Luciferase activity from the -2,090 actin-luciferase chimeric gene increased 127% compared with the contralateral control ALD muscle. Luciferase activities driven by the -424, -202, and -99 actin promoters were 179, 134, and 378% higher, respectively, in the stretched ALD muscle than in the contralateral control ALD muscle. Luciferase activity from the -77 deletion construct was not different between stretched and control muscles. These data indicate that the gene region responding to stretch is downstream of -99 and imply, but do not conclusively prove, that the region between -99 and -77, which contains serum response element 1, contributes to the stretch-induced increase in skeletal alpha-actin promoter activity in the ALD muscle.

Actins↗
PubMed1995

Hypertrophy and proliferation of skeletal muscle fibers from aged quail.

The purpose of this study was to determined whether fibers in the anterior latissimus dorsi (ALD) muscle from aged Japanese quail have decreased hypertrophic or proliferative responses to 30 days of stretch overload compared with fibers from adult birds. Two groups of quail were studied, 12-wk-old quail (adult; n = 16) and 90-wk-old quail (aged; n = 16). The left wing of each bird was overloaded with a weight corresponding to 10% of the bird's body weight, and the right wing served as the intra-animal control. Quails were killed after 30 days of stretch overload. Total fiber number was quantified by counting all the fibers in a transverse section from the midbelly of the ALD muscle. ALD muscles in aged quails retained the capacity to increase their muscle mass (145%), total fiber number (49%), and fiber cross-sectional area (54%) in response to stretch overload. The ALD muscle in aged quail had a significantly lower increase in muscle mass (33%) and mass corrected for nonmuscle tissue (36%) compared with the ALD from young adult birds. Age had no effect on fiber type distribution shifts with stretch. These results suggest that although muscles in old birds have a substantial ability to adapt to enlarge, stretch-induced hypertrophy is attenuated in muscles from old quail.

Aging↗
PubMed1993

Care manager/nurse manager: a blending of roles.

Excellent clinicians often are "promoted" to management positions. Lack of involvement in patient care can lead to diminished nurse manager satisfaction, so job enrichment and enhancement must be as important as efficiency and economy as healthcare undergoes reform. A study of 314 patients from 20 DRG categories revealed a statistically significant shortened length of stay and a savings of at least $552 per care-managed patient. Satisfaction was widespread among nurses, patients and physicians and a collaborative spirit developed between nurses and physicians. The blended care manager/nurse manager role alleviates much frustration and conflict and enriches the performance of the manager.

Delivery of Health Care↗
PubMed1990

Elective surgery without transfusion: influence of preoperative hemoglobin level and blood loss on mortality.

To clarify the widespread practice of preoperative transfusion to attain a 10 g/dL level of hemoglobin, the relationship between preoperative hemoglobin level, operative blood loss, and mortality was studied by analyzing the results of 113 operations in 107 consecutive Jehovah's Witness patients who underwent major elective surgery. Ninety-three patients had preoperative hemoglobin values greater than 10 g/dL; 20 had preoperative hemoglobin levels between 6 to 10 g/dL. Mortality for preoperative hemoglobin levels greater than 10 g/dL was 3 of 93 (3.2%); for preoperative hemoglobin levels between 6 to 10 g/dL, mortality was 1 of 20 (5%). Mortality was significantly increased with an estimated blood loss of greater than 500 mL, regardless of the preoperative hemoglobin level (p less than 0.025). More importantly, there was no mortality if estimated blood loss was less than 500 mL, regardless of the preoperative hemoglobin level. From these data, we conclude that: (1) Mortality in elective surgery appears to depend more on estimated blood loss than on preoperative hemoglobin levels; and (2) Elective surgery can be done safely in patients with a preoperative hemoglobin level as low as 6 g/dL if estimated blood loss is kept below 500 mL.

Adolescent↗
PubMed1989

Familial congenital diaphragmatic hernia is an autosomal recessive variant.

Forty families that have had more than one sibling with a congenital diaphragmatic hernia have been identified. The 85 children among the 40 families describe a subset of congenital diaphragmatic hernia displaying an autosomal recessive inheritance mode. The chance of a diaphragmatic hernia among siblings within this subset is 25%.

Cohort Studies↗
PubMed1985

An assessment of the prevalence of hepatitis B among health care personnel in Victoria.

The prevalence of past infection with hepatitis B virus in health care personnel was investigated by questionnaire and by a serological survey of personnel in a representative selection of Victorian hospitals and institutions. According to the available data, hepatitis B does not appear to have been a major infection problem among health care personnel in Victoria. The only occupational group that clearly is at an increased risk of acquiring the infection is the dental profession. Nursing staff members in institutions for the mentally retarded may also be at a higher risk. The findings of this investigation were used as a basis to frame recommendations for the vaccination of health care workers in Victoria against hepatitis B.

Australia↗
PubMed1984

Imperforate anus: the neurologic implication of sacral abnormalities.

The association of imperforate anus with bony sacral abnormalities and neurologic deficits is well recognized. These neurologic deficits have been considered static rather than progressive. However, recent experience indicates that some patients may develop progressive neurologic problems due to spinal cord lesions that are amenable to neurosurgical correction. To investigate the frequency of such lesions, routine myelography of imperforate anus patients with sacral anomalies was undertaken. The extraordinarily high incidence of unsuspected lesions known to cause progressive bowel, bladder, and musculoskeletal dysfunction is the basis of this interim report. Thirty percent of patients with anorectal abnormalities had sacral dysplasia. Of the nine patients undergoing myelography to date, eight have been abnormal. Six children had a tethered spinal cord, one had narrowing of the bony spinal canal and dural sac stenosis, and one an anterior meningocele. Spinal cord conditions that may cause deterioration of bowel, bladder, and extremity function should be defined and corrected before irreversible damage occurs. Because of the high incidence of spinal cord lesions detected in these patients with coexisting anorectal and sacral anomalies, routine screening for spinal cord lesions is recommended.

Anus, Imperforate↗
PubMed1984

The accuracy of abbreviated esophageal pH monitoring in children.

Extended (18 to 24 hour) esophageal pH monitoring establishes the diagnosis of gastroesophageal reflux (GER) utilizing a pH score, and relates respiratory symptoms to GER when the mean duration of sleep reflux (ZMD) is prolonged. A disadvantage of this method is the expense of overnight hospitalization. We performed extended esophageal pH recordings in 66 consecutive children (1 week to 15 years old) being evaluated for GER. Six portions of the 18- to 24-hour esophageal pH recording were compared to the complete record in an attempt to define the relative accuracy of abbreviated monitoring periods. The abbreviated monitoring periods included the 30 minutes after apple juice feedings (30 minutes AJ), the 2 hours after apple juice feedings (2 hours PC AJ), the 2 hours after milk-formula feedings (2 hours PC MF), the 8 hours with two feedings of apple juice (8 hours AJ), the 8 hours with two feedings of milk formula (8 hours MF), and the first 12 hours of recording (1st 12 hours). The accuracy relative to the 18- to 24-hour recording was poor for 30 minutes AJ, 2 hours PC AJ, and 2 hours PC MF periods (30% to 58%). An improved accuracy occurred during 8-hour AJ periods (29/31, 94%) in children without respiratory symptoms. Although the accuracy in patients with respiratory symptoms was best during 8-hour MF (31/35, 89%) and 1st 12-hour (33/35, 94%) periods, a high false-negative rate for the ZMD (31% to 41%) during abbreviated pH monitoring indicates that many patients with reflux-induced respiratory symptoms will be unrecognized.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗