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Biomedical subjects

S C Cooper

Publications and source records attributed to S C Cooper.

13 recordsLinked to original sources
PubMed2001

A natural history of cleidocranial dysplasia.

Cleidocranial dysplasia (CCD) is an autosomal dominant skeletal dysplasia associated with clavicle hypoplasia and dental abnormalities. The condition is caused by mutations in the CBFA1 gene, a transcription factor that activates osteoblast differentiation. Clinical characteristics associated with CCD have previously been described in case reports and small case series. This study was undertaken to gain a more complete delineation of clinical complications associated with CCD. The study population was composed of 90 CCD individuals and 56 relative controls ascertained from genetic and dental practices in the United States, Canada, Europe, and Australia. A number of previously unrecognized complications were significantly increased including: genua valga, scoliosis, pes planus, sinus infections, upper respiratory complications, recurrent otitis media, and hearing loss. Primary Cesarean section rate was significantly increased compared to relative controls and the general population rate. Finally, dental abnormalities, including supernumerary teeth, failure of exfoliation of the primary dentition, and malocclusion, are serious and complex problems that require intervention. Clinical recommendations based on the results of this study are included.

Adolescent↗
PubMed2001

Conjunctival flora observed in 70 healthy domestic rabbits (Oryctolagus cuniculus).

Conjunctival swabs were taken from both eyes of 70 healthy domestic rabbits and cultured to determine the microbial population. Bacteria were recovered from 83 per cent of the specimens. DNase-negative Staphylococcus species (57 per cent) were the most commonly recovered organisms followed by Micrococcus species (25 per cent) and Bacillus species (19 per cent). Other organisms isolated included Stomatococcus species (8 per cent), Neisseria species (8 per cent), Pasteurella species (6 per cent), Corynebacterium species (6 per cent), Streptococcus species (6 per cent) and Moraxella species (4 per cent), and other bacteria were isolated less frequently. Statistical analysis showed that there appeared to be no significant difference between the bacterial isolation rates from different breeds of rabbit. Significantly more of the swabs taken from young rabbits yielded cultivable bacteria than did those taken from rabbits over 12 months of age.

Animals↗
PubMed2001

Effects of stretch or distention on phenylephrine-induced constriction of human coronary artery bypass grafts.

OBJECTIVE: To determine the effects of grafting saphenous veins into the arterial circulation and to compare the responsiveness of saphenous veins and mammary arteries to vasoconstrictors (phenylephrine or potassium) and a vasodilator (the calcium antagonist isradipine). DESIGN: Prospective, controlled, in vitro study. SETTING: Laboratory facility in a university teaching hospital. PARTICIPANTS: Small excess segments of internal mammary arteries or saphenous veins obtained from patients undergoing coronary artery bypass graft surgery. INTERVENTIONS: Vessel segments were cut into rings to measure isometric tension development in isolated tissue chambers. The law of LaPlace for a cylinder was applied to determine tensions in vitro corresponding with arterial or venous tensions in vivo or distending pressures ex vivo. MEASUREMENTS AND MAIN RESULTS: Stretching saphenous vein rings from venous to arterial tensions reduced maximal phenylephrine-induced constriction but did not alter their dose response to phenylephrine, potassium, or isradipine. At arterial tensions, potassium, but not phenylephrine, was more potent in constricting mammary artery than saphenous vein; isradipine was more potent as a vasodilator of potassium-constricted mammary artery than saphenous vein. Maximal phenylephrine-induced or potassium-induced constriction was no different for either vessel at arterial tensions; however, prior distention of veins to tensions corresponding with pressures of 200 or 300 mmHg significantly (p < 0.01, Dunnett's test) reduced subsequent constriction. CONCLUSION: Phenylephrine may be more likely to constrict native internal mammary arteries than distended autogenous saphenous vein grafts in vivo because high-pressure distention of veins markedly inhibits their vasoreactivity.

Coronary Artery Bypass↗
PubMed2001

Nonprescription tinted eyewear optical accuracy study.

BACKGROUND: Nonprescription tinted eyewear, commonly referred to as noncorrective sunglasses or plano sun eyewear, often induce measurable amounts of prismatic deviation. With high-wrap eyewear this effect becomes more pronounced. The purpose of this project was to assess the amount of horizontal and vertical prismatic deviation induced by some popular premium plano sun eyewear intended for use by athletes. METHODS: Prismatic deviations for two identical pairs of high-wrap, steep base curve, plano sun eyewear from each of six prominent national brands were measured in both primary gaze and along a peripheral line of sight 30 degrees to the right of straight-ahead. RESULTS: Most of the eyewear induced base-out and base-down prism in each lens in primary gaze. All eyewear induced base-in prism with temporal gaze and base-out prism with nasal gaze at 30 degrees laterally. Most eyewear induced base-down prism with lateral gaze as well. CONCLUSIONS: Plano sun eyewear is often purchased for use in bright environments during visually demanding sports, such as golf, baseball, and volleyball. It is well-documented that athletes possess superior visual function as compared to nonathletes or lesser-level athletes. Further studies are indicated to determine the impact of this prism on the average wearer and the elite athlete.

Convergence, Ocular↗
PubMed1997

Direct effects of triiodothyronine on human internal mammary artery and saphenous veins.

OBJECTIVE: Thyroid hormone (3,5,3'-triiodo-L-thyronine is under investigation as a positive inotrope and vasodilator for patients undergoing cardiac surgery. This study determined the direct effects of triiodothyronine on human blood vessels. DESIGN: Prospective, controlled, in vitro study. SETTING: Laboratory facility in a university teaching hospital. PARTICIPANTS: Small excess segments of internal mammary arteries or saphenous veins were obtained from patients undergoing coronary artery bypass surgery. INTERVENTIONS: Vessel segments were cut into rings to measure isometric tension development in isolated tissue baths containing Krebs-Ringer bicarbonate solution at 37 degrees C. Rings were prestretched in vitro to resting tensions analogous to mean arterial or central venous pressures in vivo and then constricted with potassium or phenylephrine. Rings were exposed to increasing concentrations of triiodothyronine (4 x 10(-12) to 1 x 10(-4) mol/L) to obtain dose-response curves. MEASUREMENTS AND MAIN RESULTS: High concentrations (> or = 3.3 x 10(-5) mol/L) of trilodothyronine produced dose-dependent relaxation of preconstricted rings. The relaxation was not selective for arteries or veins at arterial resting tensions, and with either potassium or phenylephrine as a vasoconstrictor. Propranolol had little effect on subsequent triiodothyronine-induced relaxation of potassium-constricted rings at resting arterial tensions. CONCLUSIONS: Triiodothyronine, in supraphysiological and suprapharmacological concentrations, dilates preconstricted rings of human blood vessels in vitro; however, triiodothyronine had no demonstrable vasomotor effects on human internal mammary artery or saphenous vein in clinically relevant concentrations (10(-9) to 10(-8) mol/L). Triiodothyronine administration in vivo most likely has little direct effect on the tone of human vascular smooth muscle, particularly coronary artery bypass conduits.

Blood Pressure↗
PubMed1989

17-beta-estradiol increases mitogenic activity of medium from cultured preadipocytes of massively obese persons.

Having reported that omental preadipocytes from massively obese persons release into the culture medium proteins mitogenic for preadipocytes, this study aimed to determine whether estrogens contribute to the production of these factors. Sub-cultured omental preadipocytes from 13 massively obese women were grown in the presence or absence of 17-beta-estradiol, and during the last 24 h the conditioned medium was prepared in the absence of serum. Media from cells of 8 of 13 subjects contained significantly higher mitogenic activity when grown in the presence of 17-beta-estradiol. 17-Alpha-estradiol was not effective. The bioassay system involved rat perirenal preadipocytes, since these have been well characterized. Partial purification by gel filtration chromatography indicated that the estrogen-dependent factors had Mr greater than 250,000 and approximately 30,000. Thus, estrogens might contribute to the development of massive obesity in genetically susceptible subjects by promoting the production of paracrine/autocrine principles by adipose cells.

Adipose Tissue↗
PubMed1988

Hormonal effects of an induction dose of etomidate for patients undergoing urgent myocardial revascularization.

The use of etomidate for induction of anesthesia in patients requiring urgent coronary artery surgery provides good cardiovascular stability. However, long-term etomidate infusions may cause transient signs of adrenocortical suppression. The purpose of this study was to determine whether an induction bolus dose of etomidate would cause clinically relevant endocrine dysfunction in urgent coronary artery bypass patients. With institutional review board approval, 11 patients were prospectively randomized to a diazepam (control) or etomidate rapid sequence induction. The diazepam group (n=6; mean, 69 years) received 0.4 mg/kg of diazepam. The etomidate group (n=5; mean, 54 years) received 0.3 mg/kg of etomidate. Maintenance anesthesia included nitrous oxide, oxygen, pancuronium, and fentanyl in increments up to 32 microg/kg. Hemodynamics, cortisol, epinephrine, and norepinephrine were measured both intraoperatively and postoperatively. The only significant difference between the two groups in hemodynamic parameters was a higher heart rate in the etomidate group. Both agents adequately controlled the stress response to intubation as judged from the levels of epinephrine, norepinephrine. and cortisol. However, in both groups epinephrine and norepinephrine increased between intubation and removal of the aortic cross-clamp. Cortisol also increased from the time of cross-clamp removal to 12 and 24 hours post-bypass. During anesthesia and surgery in the pre-bypass period, there was a decrease in cortisol over time in the etomidate group, and there was an increase with diazepam. Thus, etomidate provided stable hemodynamics, possible mild intraoperative adrenocortical suppression, a depressed hormonal stress response to intubation, and a normal hormonal reaction to the later part of surgery and the postoperative period.

Aged↗