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Biomedical subjects

A Patterson

Publications and source records attributed to A Patterson.

At least 19 recordsLinked to original sources
PubMed2000

Comprehensive method of analyzing the results of photoastigmatic refractive keratectomy for the treatment of post-cataract myopic anisometropia.

PURPOSE: To assess the efficacy, stability, and safety of photoastigmatic refractive keratectomy (PARK) in treating post-cataract myopic anisometropia to restore binocularity and to describe a comprehensive method for analyzing the results of refractive surgery. SETTING: St. Paul's Eye Center, Royal Liverpool Hospital, Liverpool, United Kingdom. METHODS: Nineteen patients (20 eyes) with post-cataract myopic anisometropia were treated with PARK using a VISX Twenty-Twenty laser and followed for 12 months. Cataract surgery had been performed between 10 and 144 months (mean 43.4 months) previously. A comprehensive method based on Long's matrix formalism and the vech operator of Harris, in addition to the nearest equivalent sphere and cylinder, was used to analyze the refractive data. RESULTS: The mean preoperative refraction in the post-cataract eyes was -4.79 +1.17 x 0.2 and in the fellow eyes, +0.02 +0.31 x 166. Twelve months after PARK, the postoperative refraction in the post-cataract eyes was -0.90 +0.65 x 2, a significant reduction (P = .15). This postoperative refraction was not significantly different from that in the fellow eye (P = .93). The pretreatment mean uncorrected visual acuity was 0.12. It improved to 0.41 at 12 months, at which time 52% of eyes achieved a visual acuity of 0.5 or better without correction. All patients regained binocularity. At 12 months, 2 eyes (11%) showed clinically unacceptable regression; 1 eye with grade 2 haze lost 1 line of corrected visual acuity. CONCLUSIONS: Photoastigmatic refractive keratectomy reduced post-cataract myopic anisometropia, allowing restoration of binocularity in all patients. Overall, the results in this elderly population with previous ocular surgery, posterior capsule thickening, and macular degeneration are not as satisfactory as those obtained from similar treatment of physiological myopia. Stability and postoperative complications are acceptable.

Adult↗
PubMed1999

Molecular chemotherapy for breast cancer.

Gene therapy for breast cancer initially involves local or systemic delivery. Local delivery may be intrapleural or via direct injection to lesions. However, systemic delivery remains the greatest challenge with targeting, although methods using antibodies or growth factor receptor ligands have been demonstrated in preclinical models. This review focuses on the next step of using tissue-specific promoters such as Muc-1, CEA, PSA, HER-2, Myc, L-plastin and secretory leukoproteinase inhibitor promoters. All of these have demonstrated differential upregulation in breast cancer and additional specificity may be obtained by using physiological stimuli that are more frequently expressed in cancers, such as glucose regulated promoters and hypoxia response elements or radiation inducible elements. Amongst the later are the EGR-1, p21 and tissue type plaminogen activator promoters. Potential therapy genes include the prodrug activation system 5-fluorocytosine and other analogues of antimetabolites, but all of these need gap junctions to transfer the phosphorylated metabolites. Other approaches involving more freely diffusible products include cyclophosphamide, ifosfamide and thymidine phosphorylase to activate 5-deoxy-5-fluoruridine to fluorouracil. The bystander effect is important both for cell killing and for immunological and antivascular effects. Breast cancer is one type of tumour where a major clinical research effort is underway using local delivery methods. For prodrug activation systems, the use of human enzymes is desirable to prevent an immunological response that would eventually eliminate cells producing the prodrug activation system. The use of alkylating agents has an advantage over antimetabolites in that they are cytotoxic to cycling and noncycling cells, and the cytotoxic products can diffuse across cell membranes without the need for gap junctions. They also have a much steeper dose response curve than antimetabolites.

Breast Neoplasms↗
PubMed1998

Neuropeptide secretion in exercise.

Plasma concentrations of atrial natriuretic peptide immunoreactivity (irANP) and brain natriuretic peptide immunoreactivity (irBNP) in elderly normal subjects (mean age 71.1, range 66-81 years, n = 10) were examined before (rest), during (peak of exercise) and after (3 min, 6 min) a treadmill exercise test (modified Bruce protocol). An attempt was also made to determine the effect of steady state exercise (30% and 50%) and posture (supine, sitting) on circulating levels of atrial natriuretic peptide and calcitonin gene-related peptide (CGRP) in man. The results suggest that exercise gives rise to increased levels of irANP and irCGRP, but not human BNP. The study also demonstrated a >40% rise in irCGRP and irANP levels at 50% steady state exercise compared with 30% steady state exercise. irCGRP was shown to decline in the upright position compared with the supine position, and irCGRP did not rise with exercise. Although ANP is normally stored in large concentration in the atria with much less in the ventricles and BNP is derived to a much greater extent from the ventricles, the differential release rate of these peptides may make BNP concentration a more sensitive indicator of left ventricular dysfunction than ANP. The observations obtained here also raise the possibility that the ANP system may not only help to eliminate intermittent overhydration, but also participate in the postural regulation of diuresis and natriuresis and perhaps even support the maintenance of excretory kidney function in the ageing subjects.

Adult↗
PubMed1998

Immunocytochemical staining of ovarian cyst aspirates with monoclonal antibody against inhibin.

Inhibin is a peptide hormone which is produced by ovarian granulosa cells during normal follicular development. It is important that granulosa cells are recognized in fine needle aspirates (FNAs) of ovarian cystic lesions, as this allows definite recognition of a functional cyst and exclusion of a potentially neoplastic epithelial lined cyst. Occasionally the distinction between granulosa and epithelial cells may be difficult, especially when aspirates from functional cysts are unusually cellular. In the present study, FNAs from 33 ovarian cystic lesions were immunostained with a monoclonal antibody against inhibin. Nine cases of peritoneal fluid containing malignant cells in patients subsequently confirmed to have ovarian adenocarcinoma were also stained. Where possible the cytological and immunocytochemical findings were correlated with subsequent biopsy. In most cases in which cytology suggested a functional cyst there was a strong positive staining with anti-inhibin, although occasional cases were negative. One case originally thought to contain epithelial cells stained strongly positive with anti-inhibin and on review was felt to represent a cellular functional cyst. In all other cases where cells were considered to be epithelial there was no staining with anti-inhibin. The study shows that immunocytochemical staining with anti-inhibin may be of value in confirming the presence of granulosa cells, thus establishing a diagnosis of functional cyst. Although negative staining does not exclude a functional cyst, positive staining with anti-inhibin allows exclusion of an epithelial lined cyst and may avoid unnecessary surgical intervention.

Adenocarcinoma↗
PubMed1998

Preservation of skin vasoconstrictor responses in chronic atherosclerotic peripheral vascular disease.

Peripheral neuropathy is often found in ischemic limbs with nondiabetic atherosclerotic peripheral vascular disease (PVD). Sensory symptoms such as burning pain are common in severely ischemic limbs, and sympathectomy has been undertaken for ischemic rest pain. The authors assessed noninvasive quantitative skin vasomotor reflexes in toes and standard systemic cardiovascular autonomic tests in 44 PVD subjects with varying severity of limb ischemia, 30 age-matched control subjects, and nine PVD subjects associated with diabetes. Skin vasoconstrictor reflexes to inspiratory gasp, Valsalva maneuver, and postural change, and the postischemic reactive hyperemic response, were evaluated by the measurement of skin blood flow on toe pads by use of a laser Doppler flowmeter. Vasoconstrictor responses were not significantly different between PVD toes, even in severely ischemic limb, and age-matched controls. Reactive hyperemia was significantly less in PVD than in controls. Cardiovagal and systemic vasoconstrictor reflexes were also evaluated. All PVD subjects showed normal systemic cardiovascular reflexes. In contrast, these reflexes were severely impaired in diabetic PVD. The authors demonstrated that skin vasoconstrictive sympathetic reflex is preserved in chronically ischemic limbs with PVD, suggesting that sympathetic nerve fibers are relatively resistant to chronic ischemia.

Aged↗
PubMed1997

Use of 2% propofol to produce diurnal sedation in critically ill patients.

OBJECTIVE: The assessment of propofol to produce diurnal sedation in critically ill patients. DESIGN: Prospective clinical study. SETTING: Intensive Care Unit, University Hospital. PATIENTS AND PARTICIPANTS: Thirty consecutive patients admitted to the Intensive Care Unit older than 18 years who were expected to be sedated for more than 50 h. INTERVENTIONS: The patients were randomised into two groups. All received sedation with a constant background infusion of morphine and a variable infusion rate of propofol, which was altered hourly to maintain the intended sedation score. The first group received constant light sedation (CLS) over 50 h aiming for a Ramsay score of 2-3. The second group received CLS between 0600 h and 2200 h and additional night sedation (ANS) with propofol between 2200 h and 0600 h, aiming for a sedation score of 4-5. MEASUREMENTS AND RESULTS: Patients were studied for 50 h from 1800 h on the first day of admission. Recordings of heart rate, blood pressure, sedation scores and propofol and morphine infusion rates were made hourly. An APACHE II score was recorded for each patient. Sedation scores were analysed by blind visual assessment and cosinor analysis, which is used in chronobiology to examine the correlation of data with a cosine curve. Patients in the ANS group had significantly better rhythmicity of sedation levels using cosinor analysis (r = 26% v 8%) p < 0.01. There was no difference between the CLS and ANS groups with respect to age, sex or APACHE II scores. Nine out of 15 patients in the ANS group achieved diurnal sedation. Three patients in the CLS group showed diurnal rhythmicity of sedation, which can be attributed to natural sleep, and had a median APACHE II score of 12. Five patients in the CLS group and three in the ANS group showed a deep constant sedation pattern. They had high APACHE II scores (median 21.5) and an obtunded conscious level on admission due to severe sepsis. CONCLUSION: Propofol can safely provide diurnal sedation in the critically ill when titrated against the Ramsay score. Sedation levels cannot be manipulated in some severely ill patients.

APACHE↗
PubMed1997

Association between total astigmatism and myopia.

PURPOSE: To determine whether there is an association between degree of myopia and total astigmatism. SETTING: St. Paul's Eye Unit, Royal Liverpool University Hospitals, Liverpool, United Kingdom. METHODS: Refractive and keratometric data for 105 eyes of 105 patients with myopia and astigmatism who attended a photorefractive keratectomy (PRK) assessment clinic were analyzed. The refractive data of the patients having PRK were also analyzed before and after treatment. RESULTS: There was a strong correlation between total astigmatism (A) and degree of myopia. This could be represented by a linear regression line in the form A = -0.13 x myopia + 0.86 (at the corneal plane). Although there were trends, there was no significant correlation between the degree of corneal (keratometric) astigmatism and myopia. Data of 35 patients who had PRK were analyzed to determine whether the observed effect on astigmatism could have been predicted from the relationship between myopia and astigmatism. Forty-nine percent of patients with myopia and astigmatism were overcorrected by 0.6 diopter (D) (0.2 to 2.0 D), resulting in a preoperative to postoperative axis shift of 73 degrees; 40% were undercorrected by 1.2 D (0.5 to 3.1 D). Both over- and undercorrections could have been predicted from the relationship between myopia and astigmatism. CONCLUSIONS: The total amount of astigmatism in the myopic eye is proportional to the degree of myopia. The amount that one intends to treat should, therefore, be modified according to the amount of myopia to be treated, as determined by the relationship between the degree of astigmatism and myopia.

Adult↗
PubMed1997

Immunohistochemical staining of hepatocellular carcinoma with monoclonal antibody against inhibin.

Inhibin is a peptide hormone produced by ovarian granulosa cells. During a recent study investigating the immunohistochemical staining of ovarian granulosa cell tumours and other neoplasms with an anti-inhibin monoclonal antibody, we identified strong cytoplasmic staining of hepatocytes. In the present study we investigated the immunostaining of hepatocellular carcinoma and other neoplasms involving the liver with anti-inhibin to determine whether the antibody may be of value in the differential diagnosis of hepatic neoplasms. Immunostaining for alpha-fetoprotein was also performed. With anti-inhibin there was positive, generally strong, cytoplasmic staining of 17 of 19 cases of hepatocellular carcinoma, including the pleomorphic and glandular variants. There was positive staining of six of 20 cases of adenocarcinoma. In these, positive staining was generally focal, of weak intensity and involved the luminal surface of neoplastic glands. There was no staining of five cases of neuroendocrine tumour. There was positive staining for alpha-fetoprotein in 13 of 19 cases of hepatocellular carcinoma and in two of 20 cases of adenocarcinoma but no staining of neuroendocrine tumours. Immunostaining with anti-inhibin antibody may be of value in the differentiation of hepatocellular carcinoma from other neoplasms involving the liver. The antibody is a more sensitive, but less specific, immunohistochemical marker for hepatocellular carcinoma than is alpha-fetoprotein.

Adenocarcinoma↗
PubMed1997

Propofol 2% in critically ill patients: effect on lipids.

OBJECTIVE: To investigate the concentrations of triglyceride, cholesterol, and high-density lipoprotein during a 50-hr infusion of 2% propofol, starting within 24 hrs of admission to the intensive care unit (ICU). DESIGN: Prospective, clinical study. SETTING: ICU, university hospital. PATIENTS: Thirty adult patients, who were ventilated and expected to be sedated for >2 days, were studied for 50 hrs, beginning at 1800 hrs on the first day of ICU admission. MEASUREMENTS AND MAIN RESULTS: Triglyceride, cholesterol, and high-density lipoprotein were measured at 2000, 0400, and 0800 hrs. Tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, and C-reactive protein were measured at 2000 hrs. Median cholesterol and high-density lipoprotein concentrations were at the low end of the normal range. In seven patients, peak triglyceride concentrations were >3 mmol/L up to a maximum of 4.83 mmol/L. Although there was no statistical difference in lipid concentrations between days 1 and 2, there was an apparent pattern of increasing triglyceride concentrations. There was a correlation between peak triglyceride concentration and total propofol consumption, but there was no correlation between lipids and age, gender, or Acute Physiology and Chronic Health Evaluation II scores. There was a direct correlation between triglyceride and C-reactive protein concentrations, and an inverse correlation between cholesterol and C-reactive protein. Twenty-two patients had evidence of TNF and 11 patients had an IL-6 of >1000 pg/mL, but there was no relationship between concentrations of cytokines and triglycerides in plasma. CONCLUSIONS: Infusion of 2% propofol to critically ill patients over a 50-hr period does not result in a significant increase in triglyceride concentrations. Mean cholesterol and high-density lipoprotein concentrations were low throughout the study period. There was a significant direct correlation between triglyceride and C-reactive protein and an inverse correlation between cholesterol and C-reactive protein, suggesting that the changes in lipids in critically ill patients may be partly attributable to the acute-phase response.

APACHE↗
PubMed1997

Recent advances in surgery for emphysema.

Volume reduction surgery is based on the removal of volume-occupying but nonfunctioning emphysematous lung, which is thought to improve pulmonary elastic recoil. The reduction in thoracic volume may also improve thoracic cage and inspiratory muscle function. In addition, dyspnea is lessened, exercise tolerance is increased, and measured pulmonary function is improved. Alveolar gas exchange may also be improved. Selection criteria include marked airway obstruction secondary to emphysema, marked hyperinflation of the chest wall, and regional heterogeneity in the distribution of the emphysema. The best results are obtained with a bilateral procedure utilizing stapling resection. The two surgical approaches are median sternotomy and video-assisted thoracic surgery.

Endoscopy↗
PubMed1997

Histopathology and molecular cytogenetics of a corneal opacity associated with the trisomy 8 mosaic syndrome (46,XY/47,XY, +8).

The trisomy 8 mosaic syndrome (Tr8MS), karyotype 46,XY/47,XY, +8, is a rare multisystem disorder that may be associated with corneal opacity. We report the case of a dysmorphic infant with multiple congenital abnormalities referred to our unit with a congenital corneal opacity. Subsequent chromosomal analysis of peripheral leucocytes demonstrated constitutional Tr8MS. At 4 years of age, lamellar keratoplasty was performed. Histological examination confirmed the lesion to be consistent with a corneal choristoma. Cytogenetic studies using in situ hybridisation techniques showed the presence of trisomic cells in cell culture derived from the tissue in higher proportion (92%) than in the blood (44%). Amplification of the c-myc oncogene on chromosome-8 could not be detected in cells cultured from the corneal lesion. Although not proof, these findings lend support to the concept of the corneal lesion representing a focus of viable trisomic cells rather than an inflammatory response to a nidus of effete cells.

Abnormalities, Multiple↗
PubMed1996

Cost-effectiveness decision analysis of intramuscular ceftriaxone versus oral cefixime in adolescents with gonococcal cervicitis.

STUDY OBJECTIVE: We compared the cost-effectiveness of two single-dose treatment strategies for adolescents with uncomplicated Neisseria gonorrhoeae cervicitis. METHODS: We used a cost-effectiveness decision- analysis model to compare the two methods: the standard, ceftriaxone 125 mg given by IM injection; and an alternative, cefixime 400 mg given orally. The effect of the costs associated with the risk of accidental needlestick during IM administration was also evaluated. Key baseline assumptions (with ranges, when tested) were from the literature or costs to our hospital. These included ceftriaxone, $8.60 per dose; cefixime, $4.67 per dose; ceftriaxone efficacy, 98% (range, 94.9% to 100%); cefixime efficacy, 97% (94.1% to 100%); and a 15% probability of pelvic inflammatory disease (PID) related to failed treatment. We included costs for PID necessitating hospitalization, disseminated gonococcal infection, infertility, and ectopic pregnancy. Assumptions related to accidental needlestick included the rate of needlesticks with the disposable syringe, 6.9 per 100,000 injections (range, 0 to 69); cost of accidental needlestick to hospital; risk of HIV seroconversion after needlestick exposure to HIV-infected blood, .36% (range, 0% to .86%); rate of HIV infection in 15- to 19-year-olds attending sexually transmitted diseases clinics, .4% (range, 0 to 5); and lifetime treatment costs for a person with HIV. RESULTS: At baseline values the model favored ceftriaxone ($45 per patient) or cefixime ($59 per patient). However, over the range of efficacy of both drugs, two-way sensitivity analysis revealed no consistent cost advantage for either drug. The model was also insensitive to the economic effects associated with the risk of accidental needlestick during IM injection. CONCLUSION: over the range of efficacy by the 95% confidence intervals of both drugs, our analysis demonstrated no clear cost advantage for either. The economic effects of accidental needlestick do not change this conclusion. Compared with the IM alternative, oral cefixime is painless to the patient and simpler for the practitioner to administer. Oral cefixime also eliminates the psychologic effects associated with needlesticks in health care workers. For these reasons, we favor the use of oral cefixime for uncomplicated gonococcal cervicitis in adolescents.

Administration, Oral↗
PubMed1996

Effect of centralized intake on outcomes of substance abuse treatment.

OBJECTIVE: State governments are exploring the potential of various forms of case management to control the costs of substance abuse treatment programs. This report describes an experimental program in one Iowa county in which clients are assessed and referred elsewhere if treatment is needed. Outcomes of clients in that county are compared with those of clients served elsewhere in the state. METHODS: All claims submitted by provider agencies to the Iowa Department of Public Health for substance abuse treatment of eligible clients in 1994 were analyzed to test the effect of the experimental intake-and-referral program on clients' utilization of outpatient treatment, rate of treatment completion, and rate of abstention at discharge from treatment. RESULTS: In the county with the experimental program, 27 percent of clients recommended for treatment actually attended, compared with 48 percent in other counties. Clients who used the experimental program were also less likely to complete treatment. These differences persisted after adjusting for baseline differences in client characteristics. CONCLUSIONS: Lower utilization arising from failure to attend recommended treatment may reduce treatment costs but is not the intended outcome of the intake-and-referral program. Failure to complete treatment also is an adverse outcome. Outcomes of various types of case management programs should be carefully evaluated before statewide implementation is considered.

Adult↗
PubMed1995

Short communication: selecting input distributions for use in Monte Carlo simulations.

Monte Carlo analysis is increasingly employed as a means of quantifying uncertainties in risk assessment. However, the output of any Monte Carlo analysis is extremely sensitive to the input distributions used. In this paper we present a simple set of guidelines for the selection of input distributions. The guidelines involve allocating variables with unknown distributions to appropriate distributional "classes," based on the range of possible values that could be obtained for the data and known characteristics about the behavior of the variable. If the class of distribution is not identifiable, then variables can be related to a specific distribution using goodness-of-fit techniques. If these identification schemes fail, bootstrapping techniques may be used to generate a sampled distribution from the available data. Finally, "default" distributions may be employed using analogous data if site-specific data are unavailable.

Mathematics↗
PubMed1992

Cyclosporine nephrotoxicity in lung transplant recipients.

End-stage lung disease has been treated successfully by lung transplantation (LTXP) at our institution since 1983. We report on the renal function of 30 LTXP recipients who were followed for at least 6 months (mean, 39 months; range, 6-60 months). All patients received quadruple immunosuppressive therapy including cyclosporine A, with a trough serum level (RIA) between 150 and 250 ng/ml for the first 6 months between 125 and 150 mg/ml after 6 months. The mean serum creatinine (SeCr) increased from a baseline value of 75 +/- 3.5 to 182 +/- 13.9 microM at the end of the follow-up. The greatest change in SeCr occurred within the first 6 months post LTXP. Fifteen of 30 patients who were initially normotensive required at least one antihypertensive medication post LTXP. By the end of the follow-up, 9 patients had SeCr > 200 microM. Two patients in this institution have progressed to end-stage renal disease requiring dialytic therapy. CsA nephrotoxicity has emerged as a major source of morbidity in the lung transplant population. Nephrotoxicity occurs early, and there does not appear to be any trend toward reversibility despite a lowering of the dose. Renal parenchymal injury may be progressive, despite an apparent plateau of the SeCr in some patients.

Adult↗
PubMed1992

Management of women with a cervical smear showing a mild degree of dyskaryosis: a review of policy.

Three hundred and thirty-seven women who presented for the first time with a cervical smear showing a mild degree of dyskaryosis were followed for a minimum period of 3 years and 9 months. Of the 305 women with complete cytological and histological records, 178 were biopsied and 127 remained on cytological follow up. In the biopsied group one case of microinvasive squamous cell carcinoma was diagnosed within 1 year of the patient's first abnormal smear. A further 24% showed cervical intraepithelial neoplasia (CIN) I, 17% showed CIN II and 29% showed CIN III. The overall regression rate for the group of 305 women was 34%. Our results indicate that cytological surveillance is acceptable provided that biopsy is advised when dyskaryosis persists. No major modifications to laboratory policy are indicated and in approximately 34% of cases an unnecessary hospital referral would be avoided.

Adult↗