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Biomedical subjects

S Carter

Publications and source records attributed to S Carter.

At least 37 records · Page 2Linked to original sources
PubMed1998

Hemostasis of punctured blood vessels using high-intensity focused ultrasound.

The hemorrhagic complications of vascular injury can be significant. We report on the use of high-intensity focused ultrasound (HIFU) to stop the hemorrhage of punctured blood vessels in pigs. Two HIFU transducers with frequencies of 3.5 and 2.0 MHz, each equipped with a water-filled conical housing, were used. Major blood vessels (femoral artery and vein, axillary artery, carotid artery and jugular vein), 2-10 mm in diameter, of anesthetized pigs were exposed surgically and punctured with 14- and 18-gauge needles to produce moderate to profuse bleeding. Complete hemostasis was achieved in less than 3 min of HIFU treatment in most blood vessels, and all vessels were patent after the treatment. Both HIFU frequencies were effective in producing hemostasis. Gross examination of the HIFU-treated vessels showed a consistent hardening of the soft tissue surrounding the blood vessels, providing a seal for the puncture hole. Microscopic examination of the vessels showed a remarkably localized HIFU treatment, resulting in coagulation of the adventitia, and an extensive fibrin network around the vessels and in the puncture hole. The vessel walls exhibited focal swelling, without evidence of irreversible injury. HIFU may provide a useful method for achieving hemostasis of punctured and traumatized blood vessels in a variety of clinical settings.

Animals↗
PubMed1998

Evidence of CNS impairment in HIV infection: clinical, neuropsychological, EEG, and MRI/MRS study.

OBJECTIVES: To identify by clinical examination, EEG, MRI, and proton spectroscopy, and neuropsychological assessment the prevalence of signs of CNS involvement in patients infected with HIV, and to relate such findings to the evidence of immunosuppression. METHODS: The design was a cross sectional analysis of a cohort of male patients with infected HIV with an AIDS defining diagnosis or low CD4 count (<350), and seropositive asymptomatic subjects, both groups being followed up in a longitudinal study. Control groups consisted of seronegative subjects from the same genitourinary medicine clinics. RESULTS: This report sets out the cross sectional findings at the seventh visit in the longitudinal study. Patients with AIDS had more signs of neurological dysfunction, poorer performance on a neuropsychological test battery, were more likely to have an abnormal EEG, and to have abnormalities on MRI. They more often had cerebral atrophy, abnormal appearing white matter, and abnormal relaxometry and spectroscopy. There was little evidence of abnormality in seropositive people who had a CD4 count >350 compared with seronegative people from a similar background. CONCLUSIONS: Detailed testing failed to disclose significant CNS impairment without immunosuppression in men infected with HIV. Findings from MRI and magnetic resonance spectroscopy (MRS) correlated with those of the neurological examination and neuropsychological assessment. A combination of such assessments offers a simple surrogate for studies of CNS involvement in HIV disease.

AIDS Dementia Complex↗
PubMed1998

Characterization and use of a commercial n-type diode system.

The characteristics of n-type diodes (linearity, temperature, dose rate, radiation damage response, directional dependence, output factors, wedge factors and percentage depth dose determinations) were investigated. Subsequently, the diodes were used clinically for in vivo dose verification during external megavoltage photon beam therapy. It has been shown that n-type diodes are easy to use and the results obtained are comparable to those reported for p-type diodes. On most occasions, n-type diodes can be used without any additional correction factors apart from regular monthly calibration. There is good agreement between the uncertainty limits estimated from the diodes' characteristics and those obtained on the basis of 2261 patient measurements.

Equipment Failure↗
PubMed1997

A sequence-ready physical map of a region of 12q24.1.

We developed a sequence-ready map of a part of human chromosome 12q24.1. We utilized a number of sequence-tagged site (STS) markers from 12q24.1 to screen large insert bacterial chromosome libraries and a chromosome 12-specific cosmid library. The clones were assembled into contiguous sets (contigs) by STS-content analysis. Contigs were extended by obtaining end sequences of bacterial clones, generation of additional STSs, rescreening the libraries, and screening the additional clones for the presence of STSs. The resulting contig covers nearly 2 Mb of DNA and provides an average marker resolution of 16 kb. Based on the STS content, we developed fingerprints of a subset of clones. The STS content and fingerprint data allowed us to define a minimal tiling path of clones. These clones are being used to sequence this part of chromosome 12. This contig contains the Ataxin 2 gene, and it covers the interval harboring the gene responsible for Darier disease.

Ataxins↗
PubMed1997

Magnetic resonance imaging of the brain and cerebral proton spectroscopy in patients with systemic lupus erythematosus.

OBJECTIVE: To investigate the prevalence and extent of cerebral changes in patients with systemic lupus erythematosus (SLE) by magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS). METHODS: SLE patients (47 women) and controls (25 women) underwent 1.5T MRI. A semiautomated segmentation technique calculated cerebrospinal fluid (CSF) and brain volumes. Proton MRS of the frontal and parieto-occipital white matter yielded metabolite ratios of N-acetyl groups (NA), choline, and creatine. RESULTS: Compared with the control group, the SLE patients more often had cerebral atrophy on MRI (32% versus 0%), confirmed by an increase in the CSF to intracranial volume ratio. The patients also had old infarcts and hemorrhages (8.5% versus 0%) and more small white matter lesions (23% versus 8% had > 5 such lesions). MRS showed relative reduction of NA peaks. Although no patient was studied when acutely ill, prior neurologic involvement was related to abnormal findings. CONCLUSION: MRI and MRS are helpful in the investigation of cerebral complications of SLE. There are chronic changes which may be ischemic in nature. Their precise cause, consequences, and prevention are current challenges.

Adult↗
PubMed1997

Liver hemostasis using high-intensity focused ultrasound.

Liver hemorrhage, the major cause of death in hepatic trauma, is notoriously difficult to control. We report on the use of high-intensity focused ultrasound (HIFU) to arrest the bleeding from incisions made in rabbit livers. A HIFU transducer, with a spherically curved aperture of 6.34 cm2 area, a focal length of 4 cm and a frequency of 3.3 MHz was used. In approximately 94% of the incisions, the hemorrhage was reduced to a slow oozing of blood in less than 2 min. The maximum temperature of liver tissue around the incision area, during HIFU application, was measured to be 86 degrees C. The mechanism of hemostasis, confirmed by histological examination, appears to be coagulative necrosis of a volume of liver tissue around the incision. We believe that acoustic hemostasis, with the unique characteristic of "volume cauterization," offers a novel method for the management of liver hemorrhage and, thus, has major clinical implications.

Animals↗
PubMed1997

Cerebral proton magnetic resonance spectroscopy in asymptomatic HIV infection.

OBJECTIVE: To determine whether proton magnetic resonance spectroscopy (MRS) demonstrates central nervous system abnormalities in asymptomatic HIV-1-infected individuals. DESIGN: Both prospective and retrospective cross-sectional analyses of MRS in asymptomatic HIV-infected individuals. SETTING: Two specialists HIV/AIDS outpatient facilities in London. PARTICIPANTS: Eighty-four HIV-1 seropositive asymptomatic men; 29 HIV-1 antibody-negative homosexual men at high-risk for HIV infection and 48 HIV-1 antibody-negative men at low-risk for HIV infection as controls. MAIN OUTCOME MEASURES: Single voxel, gradient-localized proton MRS performed at 1.5 T with 135 msec echo-time and 1,600 msec repeat-time in an 8 ml volume of interest positioned in the parieto-occipital white matter. Spectroscopic results were expressed as ratios between the areas under the N-acetyl (NA), creatine (Cr) and choline (Cho) resonance peaks. RESULTS: There were no differences between those controls at high and those at low-risk for HIV infection. Comparing the combined control groups with the asymptomatic seropositive patients there were statistically significant differences in NA/Cho, NA/Cr (both P < 0.05) and NA/(NA + Cho + Cr) (P < 0.01). CONCLUSION: Abnormalities in cerebral biochemistry may be demonstrated by proton MRS during asymptomatic HIV-1 infection.

Brain↗
PubMed1997

The sexual behaviour of international travellers at two Glasgow GUM clinics. Glasgow genitourinary medicine.

A survey of patients attending 2 Glasgow genitourinary medicine (GUM) clinics was conducted in 2 3-month periods in 1993 and 1994. Three hundred and twenty-five attendees who had travelled abroad in the preceding 3 months completed anonymous self-administered questionnaires about their sexual behaviour during these recent journeys abroad. There were 112 women and 213 men (185 heterosexuals and 28 homosexuals). Twenty-two (19.6%) women, 56 (31%) heterosexual men and 13 (42%) homosexual men had a sexual contact with a new partner while abroad. Of those who had had a new sexual contact abroad, 11 women (50% of those who had sex with a new partner) and 33 heterosexual men (59% of those who had sex with a new partner) were inconsistent users of condoms. Analysis of data found that homosexual and heterosexual men, and business travellers, are at increased risk of exposure to sexually transmitted diseases, including HIV infection, and should be targeted with safer sex health promotion prior to travel.

Adolescent↗
PubMed1997

Evaluation of pathologic criteria for acute renal allograft rejection: reproducibility, sensitivity, and clinical correlation.

This study was designed to evaluate the pathologic criteria used for acute renal allograft rejection that were developed by a panel of renal pathologists participating in the Cooperative Clinical Trials in Transplantation, a National Institutes of Health-supported, multicenter research group. The panel defined three categories of acute rejection. (1) Type I: mononuclear infiltrate in > or =5% of cortex, a total of at least three tubules with tubulitis in 10 consecutive high-power fields from the most severely affected areas, and at least two of the three following features: edema, activated lymphocytes, or tubular injury. (2) Type II: arterial, or arteriolar, endothelialitis with or without the preceding features. (3) Type III: arterial fibrinoid necrosis or transmural inflammation with or without thrombosis, parenchymal necrosis, or hemorrhage. Using these criteria, and without any knowledge of the clinical course or original diagnosis, a rotating panel of three pathologists agreed with the original study pathologist's diagnosis of the presence or absence of rejection in 259 of the 286 biopsies (91%) used for this analysis (kappa = 0.80). The sensitivity to establish the diagnosis of rejection was 91% for a single core and 99% for two cores. To validate the diagnostic criteria, the thresholds for number of tubules with tubulitis and the percent infiltrate were varied, and the pathologic diagnosis was compared with the clinical course. The greatest agreement occurred with a threshold of > or =1 tubule with tubulitis and > or =5% cortex with interstitial infiltrate (91%). Clinically severe rejection episodes were correlated with the type of rejection (type I, odds ratio [OR] 6.2; type II, OR 37.9). Type II rejection was more likely to be clinically severe than type I (OR 6.1). Analysis of other individual pathologic features revealed a correlation with clinical severity for endothelialitis (OR 13.2), interstitial hemorrhage (OR 13.2), and the presence of glomerulitis (OR 3.7) (all P < 0.05). The extent of tubulitis or of the interstitial infiltrate did not correlate with severity (P > 0.05). It is concluded that these criteria are simple, reproducible, and clinically relevant. These data should lead to further refinement of the diagnostic systems for renal allograft rejection.

Acute Disease↗
PubMed1997

Shortening of the first metatarsal following closing base wedge osteotomy.

Shortening of the first metatarsal has been one of the reported complications noted in association with base osteotomies. Previous studies have used radiographs as a means of assessing metatarsal length, the reliability of which has been subject to question. In this study, the authors have determined the amount of shortening that may be anticipated with a closing base wedge osteotomy of the first metatarsal through an experimental model. A mathematical model was also devised that confirmed these findings. Additional studies were performed to determine what influences other variables may have on this procedure.

Hallux Valgus↗
PubMed1997

Incidence of spontaneous subarachnoid hemorrhage among Hispanics and non-Hispanic whites in New Mexico.

BACKGROUND AND PURPOSE: There are differences in cerebrovascular disease incidence between racial and ethnic groups. Little is known about cerebrovascular disease among Hispanics living in the southwestern United States as compared to non-Hispanic whites. This is the first study which measures and compares the incidence of spontaneous subarachnoid hemorrhage (SAH) among Hispanics and non-Hispanic whites living in Bernalillo County, New Mexico. This information may help reduce the risk and incidence of SAH. METHODS: Medical records of all possible cases of spontaneous SAH occurring during a two-year period (January 1, 1993 to December 31, 1994) among residents of Bernalillo County, New Mexico, were reviewed in all local hospitals. Hospital records were identified by ICD-9-CM codes. Medical examiner records were also reviewed for additional SAH cases occurring during the same time period. The 1990 U.S. census provided the population base. RESULTS: There were 22 spontaneous SAHs among 267,965 non-Hispanic whites and 25 spontaneous SAHs among 178,310 Hispanics. Incidence of SAH increased with age in both groups. The age- and sex-adjusted total annual incidence of SAH per 100,000 people was 3.73 among non-Hispanic whites and 9.19 among Hispanics (relative risk for Hispanics 2.46, 95% confidence interval 1.37-4.43, P = 0.003). The incidence rates among men and women were not significantly different in either ethnic group. CONCLUSIONS: The incidence of SAH among Hispanic residents of Bernalillo County, New Mexico, is approximately two and a half times higher than that among non-Hispanic whites. This suggests a higher prevalence or a greater tendency to rupture of berry aneurysms among Hispanics as compared to non-Hispanic whites. The reasons for this difference require further investigation.

Age Distribution↗
PubMed1997

Dose-response effects of raw potato starch on small-intestinal escape, large-bowel fermentation and gut transit time in the rat.

This study was designed to quantify starch digestion within the small and large bowels separately when raw potato starch (RPS) was included at 0-240 g/kg in diets fed to growing male Wistar rats. RPS was incorporated in the diets at the expense of maize starch which was expected to be almost completely digested in the small bowel. The digestibility of the maize starch was 0.99 but only 0.28 of the RPS was digested before the terminal ileum so that with increasing intakes of RPS there was a progressive increase in starch supply to the large bowel (LB). Of this starch 0.77, 0.72 and 0.73 was fermented in the large bowel when RPS constituted 80, 160 and 240 g/kg diet respectively. With increasing RPS intake, there was a curvilinear response in molar proportion of butyrate in caecal contents with a maximum value at about 80 g RPS/kg diet. The molar proportion of acetate increased linearly, that of propionate was unchanged, whilst proportions of the minor short-chain fatty acids all declined markedly with increasing RPS intake. The novel marker Bacillus stearothermophilus spores (BSS) was compared with CrEDTA in estimation of whole-gut mean transit time (MTT) when given together in a single test meal. Whilst estimates of MTT for the two markers were strongly correlated within individual rats (r2 0.72), BSS produced estimates that were 13 h longer than those based on CrEDTA. Neither marker detected a change in MTT with increasing RPS intake but, with both, the rate constant (k1) for the 'largest mixing pool' declined significantly (P < 0.001) as dietary RPS concentration was changed from 0-240 g/kg.

Analysis of Variance↗
PubMed1996

Incidence of spontaneous intracerebral hemorrhage among Hispanics and non-Hispanic whites in New Mexico.

OBJECTIVE: To compare the incidence of spontaneous intracerebral hemorrhage (ICH) among Hispanics and non-Hispanic whites living in Bernalillo County, NM. BACKGROUND: There are differences in cerebrovascular disease incidence between racial and ethnic groups. Knowing these differences is likely to optimize stroke prevention and evaluation. METHODS: Medical records review of all possible cases of ICH occurring between January 1, 1993 and December 31, 1993 among residents of Bernalillo County, NM, in all local hospitals. Hospital records were identified by ICD-9-CM codes. Also, State Medical Examiner records review for additional ICH cases occurring during the same time interval. The 1990 U.S. census provided the population base. RESULTS: There were 47 spontaneous ICHs among 267,965 non-Hispanic whites and 39 spontaneous ICHs among 178,310 Hispanics. Incidence of ICH rises exponentially with age in both groups. The age- and sex-adjusted total annual incidence of ICH per 100,000 people is 16.6 among non-Hispanic whites and 34.9 among Hispanics (relative risk for Hispanics 2.10, 95% confidence interval 1.35 to 3.26, p = 0.001). The age-adjusted incidence rates among men and women are not significantly different in either ethnic group. CONCLUSION: The incidence of spontaneous ICH among Hispanic residents of Bernalillo County, NM, is approximately twice that among non-Hispanic whites. The reasons for this difference require further investigation.

Adult↗
PubMed1996

Can surgical gloves be made thinner without increasing their liability to puncture?

A new process has been used to develop Biogel Super-Sensitive gloves which are thinner but theoretically as strong as standard Biogel gloves. The two types of glove were compared for their effects on manual sensitivity and dexterity in a randomised controlled trial. The Super-Sensitive gloves impaired sensitivity significantly less than standard gloves but made no difference to the ability to tie knots. No statistically significant difference was shown in the resistance to perforation between the two types of gloves. Surgeons who prefer more sensitive but relatively strong gloves should find the new gloves useful.

Equipment Design↗