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Biomedical subjects

S Carter

Publications and source records attributed to S Carter.

At least 73 records · Page 4Linked to original sources
PubMed1998

Experimental autoimmune myocarditis produced by adoptive transfer of splenocytes after myocardial infarction.

One possible mechanism for neurohumoral activation after myocardial infarction may be the generation of an immune response against cardiac self-antigens. We hypothesize that if there is a T cell-mediated reaction to self-antigens, the transfer of splenic lymphocytes from postinfarct rats into syngeneic rats with normal hearts should result in a T cell-mediated autoimmune myocarditis in the healthy syngeneic rats. Rats were killed 6 weeks after coronary ligation. Splenocytes from animals with large and small infarcts were purified from spleens, activated with concanavalin A, and injected in varying doses into normal syngeneic rats. These recipient rats were killed 6 weeks later, and histopathological studies were performed. Our results demonstrate in vivo evidence of lymphocyte-mediated myocardial injury by adoptive transfer of sensitized lymphocytes from rats who developed congestive heart failure after acute myocardial infarction. The amount of infiltrate and necrosis in the recipient rats appeared directly related to the size of the infarct from the donor rats. This suggests that larger infarcts lead to a greater inflammatory response as well as a greater propensity for alteration of cardiac surface antigens or the emergence of previously sequestered antigens. None of the other organs (kidney, liver, lung, or brain) had evidence of infiltrates. Two-dimensional echocardiography did not reveal systolic dysfunction. This study provides direct evidence of autoimmune myocardial injury produced by adoptive transfer of concanavalin A-activated splenocytes after myocardial infarction. We propose that neurohumoral activation early in the postinfarction period triggers a series of specific inflammatory and immunological events that lead to formation of specific clones of T cells. When these are activated and transferred into normal rats, cardiac-specific cellular infiltration occurs, occasionally accompanied by myocardial necrosis. This model should help to further explore the link between neurohumoral activation after myocardial infarction and the subsequent immune alterations that might be associated with the development and/or progression of congestive heart failure. Additionally, this might be a useful model in which to study other immune-mediated cardiomyopathies.

Adoptive Transfer↗
PubMed1998

The Geometry and Force Field of Thioformaldehyde.

A six-dimensional variational code, recently presented for the determination of the rovibrational energy levels of formaldehyde, has been used to refine a quartic potential surface of thioformaldehyde and simultaneously to optimize its geometry. The parameters have been adjusted to obtain as good agreement as possible with the known J = 0 vibrational energy levels and the corresponding observed J = 1 rotational lines of both H2CS and D2CS, where known. This is a highly nonlinear problem, and it is not possible to refine separately the geometry and force field. We have simultaneously optimized the HCS bond angle, the quadratic force field, and a partial cubic and quartic force field. Fermi and Coriolis resonances have been reproduced. The predicted geometry is CH = 1.0856 Å, CS = 1.6110 Å, HCS = 121.88 degrees. Predictions are made for overtones and combination bands of H2CS and D2CS. Furthermore, a prediction is made for the unobserved fundamental nu5 of D2CS, which lies very close to 3nu6. Copyright 1998 Academic Press.

Journal Article↗
PubMed1998

Delay in the presentation of colorectal carcinoma: a review of causation.

This review paper studies the reasons behind the delay in presentation of colorectal carcinoma. Such delay can occur at three different levels: delay on the part of the patient, delay by the general practitioner prior to patient referral and delay incurred at the hospital after patient referral. There is some evidence that patient delay has decreased in recent years; general practitioner delay is disputed by some authors, but there is considerable evidence that it exists. Hospital delay can be influenced by the general practitioner; there is evidence that it has increased in recent years and is likely to increase further with the current pressure on in-patient beds.

Attitude↗
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 role of monitoring in determining quality of life following treatment for a bone tumor.

Interviews were conducted with 34 young people who had previously been treated for a malignant bone tumor around the knee. These interviews focused on the impact of treatment on activities and perceptions of the risk of recurrence and need for future surgery A coding schema based on a "monitoring-blunting" framework was adopted (Miller, 1995). Quality of life was assessed using a generic and disease-specific measure. Based on interview data, respondents were categorized as negativistic monitors, adaptive monitors, and nonmonitors. There were no differences between groups in terms medical indicators (number of operations). Negativistic monitors reported poorer quality of life compared with the other two groups. There was no increase in nonmonitoring with time since diagnosis as reported in previous work. It is suggested that patients' self-ratings of quality of life are related to the way in which they monitor information and this may be independent of clinical function. Clinical implications, especially in terms of how potentially threatening information about late-effects of treatment are given to patients, are discussed.

Journal Article↗
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↗