Learning clinical biochemistry using multimedia interactive clinical cases.
Explore the source record for details and available documents.
Biochemistry↗
Biomedical subjects
J O'Connor
Publications and source records attributed to J O'Connor.
Expression, purification and initial characterization of the recombinant storage protein precursor of Theobroma cacao.
The gene encoding the 67-kDa cocoa storage protein precursor has been cloned from Theobroma cacao and expressed in Escherichia coli using the pET expression system. The recombinant storage protein has been renatured from inclusion bodies at 30 degrees C using 20 mM glycine-NaOH buffer, pH 10.0, containing 1 mM oxidized glutathione and 0.1% Brij. The renatured protein was purified and demonstrated to adopt a stable native conformation by optical spectroscopy. Secondary structure analysis from circular dichroism indicated the protein to be 23% alpha-helix and 38% beta-sheet, in close agreement with values obtained using a secondary structure prediction program.
Cacao↗
Skeletal muscle membrane lipids and insulin resistance.
Skeletal muscle plays a major role in insulin-stimulated glucose disposal. This paper reviews the range of evidence in humans and experimental animals demonstrating close associations between insulin action and two major aspects of muscle morphology: fatty acid composition of the major structural lipid (phospholipid) in muscle cell membranes and relative proportions of major muscle fiber types. Work in vitro and in vivo in both rats and humans has shown that incorporation of more unsaturated fatty acids into muscle membrane phospholipid is associated with improved insulin action. As the corollary, a higher proportion of saturated fats is linked to impairment of insulin action (insulin resistance). Studies in vitro suggest a causal relationship. Among polyunsaturated fatty acids (PUFA) there is some, but not conclusive, evidence that omega-3 (n-3) PUFA may play a particular role in improving insulin action; certainly a high n-6/n-3 ratio appears deleterious. In relation to fiber type, the more highly oxidative, insulin-sensitive type 1 and type 2a fibers have a higher percentage of unsaturated fatty acids, particularly n-3, in their membrane phospholipid, compared to the insulin-resistant, glycolytic, type 2b fibers. These variables, however, can be separated and may act in synergy to modulate insulin action. It remains to establish whether lifestyle (e.g., dietary fatty acid profile and physical activity), genetic predisposition, or a combination are the prime determinants of muscle morphology (particularly membrane lipid profile) and hence insulin action.
Animals↗
A prospective study of early pregnancy loss.
The New York State Early Pregnancy Detection Study was a prospective study of early pregnancy loss, between implantation and menses, in 217 women attempting to become pregnant during 1989-1992. Women collected urine samples on three consecutive mornings during the late luteal phase of their menstrual cycle, for up to 12 cycles, contributing samples for 1253 menstrual cycles. Urinary human chorionic gonadotrophin (HCG), measured using an immunoradiometric assay, was the biomarker for pregnancy. We observed a range of early pregnancy loss (EPL) rates, from a low estimate of 11.0% to a high estimate of 26.9%, depending on the definition used and the subgroup analysed. Based on a definition of 3 days of HCG concentration > or = 4.00 pmol/l, 2 days > or = 5.33 pmol/l or the last day of HCG > or = 6.67 pmol/l, we identified 115 positive cycles; 95 cycles were clinically confirmed pregnancies and 20 cycles were EPL, giving an EPL rate of 17.4% [95% confidence interval (CI) 11.0-25.6]. In addition, we observed an EPL rate of 19.5% (95% CI 11.3-30.1) for samples collected within a 15 day window around menses, and a rate of 20.3% (95% CI 11.3-32.2) for samples limited to the first three menstrual cycles. Because studies use urine collection schemes other than daily sampling, the definition of pregnancy will be crucial in defining EPL.
Abortion, Spontaneous↗
Medicaid primary care services in New York State: partial capitation vs full capitation.
BACKGROUND: Forty-nine states have applied to the Health Care Financing Administration for waivers to allow special program development for Medicaid recipients. In an effort to identify issues relevant to making the transition of its entire Medicaid population into a capitation model, New York State has encouraged the development of partial capitation and full capitation models. This paper is a critical description analysis of a 1-year experience, utilizing data provided by the New York State Department of Social Services. METHODS: Data collected by the New York State Department of Social Services were used to compare the costs for matched cohorts enrolled in partial capitation programs in which the primary care physician is paid a monthly fee to provide ambulatory primary care for Medicaid recipients; and full capitation programs in which a health maintenance organization (HMO) or a hospital-based prepaid health services program (PHSP) is paid a more encompassing monthly fee to provide a larger range of services, including inpatient, outpatient, and specialty care. RESULTS: Partial capitation programs were reported to save the state 38% compared with a matched control group enrolled in traditional, fee-for-service Medicaid (P<.05), and offered greater savings than HMOs and PHSPs (P=NS). The HMOs and PHSPs saved the state 9.3% and 16.8%, respectively, compared with traditional enrollment. Quality measures and patient satisfaction for partial and full capitation programs were equivalent. CONCLUSIONS: These data suggest that New York State primary care physicians who participated in programs that reimburse a prepaid monthly fee for outpatient primary care services achieved savings comparable to those of HMOs. A partial capitation primary care model may offer an affordable and more flexible alternative to full-service HMOs in caring for Medicaid recipients, especially in communities with limited HMO penetration.
Capitation Fee↗
Estimates of human fertility and pregnancy loss.
OBJECTIVE: To examine the fertility and pregnancy wastage rates in a group of presumably fertile couples. DESIGN: Prospective observational study of 200 couples desiring to achieve pregnancy over 12 menstrual cycles coupled with pregnancy outcome follow-up. SETTING: A university-based obstetrics and gynecological center. PATIENTS: Personal interviews and questionnaires were used to screen couples for entry into the study. Couples were counseled to have intercourse centered on predicted day of ovulation. Phase 1 included the first three cycles in which women collected daily morning urine samples, underwent midcycle postcoital tests, and, if late for their menses, presented for serum hCG testing. Phase 2 encompassed the next nine cycles in which women were contacted monthly by phone and underwent serum hCG testing if menses was delayed. Urine samples from cycles in which clinical (serum hCG) pregnancy did not occur underwent sensitive hCG testing to detect occult pregnancies. Pregnancies were followed until delivery to ascertain outcome. RESULTS: Eighty-two percent of the 200 couples followed for the entire study period conceived. The maximal fertility rate was approximately 30% per cycle in the first two cycles. This rate quickly tapered over the remainder of the study. Pregnancy wastage during phase 1 accounted for 31% of the pregnancies detected. Forty-one percent (15/36) of these losses were seen only by urine hCG testing and were categorized as occult. Eleven of these same patients later achieved clinically recognized conceptions during the study. CONCLUSIONS: These results support the concept that the efficiency of human reproduction is maximum at approximately 30% per cycle. A very significant number of these pregnancies end in spontaneous abortion. In addition, pregnancy loss before missed menses occurs in a significant proportion of women.
Abortion, Spontaneous↗
Inhaled albuterol does not inhibit cellular influx or lung injury produced by segmental antigen challenge in humans.
Many experimental protocols and published guidelines for performing bronchoscopy, bronchoalveolar lavage (BAL), bronchial biopsies, and segmental antigen challenge (SAC) of allergic asthmatic subjects recommend treating subjects with a beta-agonist prior to the procedure. However, the effect of beta-agonist pretreatment has not been reported. In a retrospective analysis of ragweed allergic subjects undergoing bronchoscopy, SAC, and BAL, we examined the effect of albuterol pretreatment on cellular influx and lung injury produced by antigen challenge. Forty-eight subjects, 17 who received no pretreatment and 31 who received four puffs of albuterol prior to bronchoscopy, comprised the study groups. No parameter monitored in BAL fluid 24 h after SAC (total cells, macrophages, neutrophils, eosinophils, lymphocytes, total protein, albumin, or eosinophil cationic protein) differed in subjects pretreated with albuterol when compared with subjects who were not pretreated. Although additional, prospective studies are warranted, we conclude that beta-agonist pretreatment of experimental subjects does not alter many aspects of the inflammatory response produced by SAC.
Administration, Inhalation↗
Vitamin A deficiency in the South Pacific.
UNLABELLED: Vitamin A deficiency is a major cause of morbidity, mortality and blindness among children. Although vitamin A deficiency is known to affect many children in developing countries, the magnitude of the problem in the South Pacific region is unclear. METHODS: Five cross-sectional surveys for vitamin A deficiency were conducted between 1989 and 1992 in the Republic of Kiribati, Tuvalu, the Republic of Vanuatu, Solomon Islands and the Cook Islands. RESULTS: In total, 10,673 children between the ages of 6 and 72 months were examined for clinical signs of vitamin A deficiency (nightblindness and xerophthalmia). The prevalence of xerophthalmia was 14.76% in the Republic of Kiribati, 1.55% in Solomon Islands, 0.59% in the Cook Islands, 0.28% in Tuvalu, and 0.11% in Vanuatu. The most common clinical findings were Bitot's spots followed by nightblindness. Xerophthalmia were more common among boys (Kiribati P < 0.001, Solomon Islands P = 0.03) and tended to occur in older preschool children (P < 0.0001). CONCLUSIONS: These studies suggest that vitamin A deficiency is a public health problem in the Republic of Kiribati and Solomon Islands.
Child↗
Peripheral ulcerative keratitis in the setting of rheumatoid arthritis: treatment with immunosuppressive therapy.
Peripheral ulcerative keratitis (PUK) is a rare but serious inflammatory eye condition that can complicate rheumatoid arthritis. PUK can be a warning sign of impending vasculitis, and cytotoxic therapy may be necessary to induce remission. We have encountered three patients with PUK in the past year. Two patients had long-standing quiescent rheumatoid arthritis who developed photophobia. Diagnosis was made by slit lamp examination. Treatment with local cyclophosphamide and prednisone resulted in prompt remission of the ulcer within 8 weeks. Cytotoxic therapy was discontinued altogether within 6 months. The third patient was also treated successfully with oral steroids and azathioprine. In all patients, sicca was noted. None of them had any evidence of systemic vasculitis. PUK, when recognized early and treated aggressively, can result in remission of the ulcer and in the prevention of vasculitis. Keratoconjunctivitis sicca can accompany PUK independent of the activity of rheumatoid arthritis.
Aged↗
Resting energy expenditure in children with phenylketonuria.
Reports have suggested that children with phenylketonuria (PKU) weigh more compared with reference data. We found lower body protein and bone mineral density in children with PKU. These children may have a predisposition becoming overweight because of an alteration in body composition, which may lower resting energy expenditure (REE). REE was measured in 30 (15 males, 15 females) children with PKU (aged 9.6 +/- 2.9 y) and in 65 (23 males, 42 females) control children (aged 11.2 +/- 3.1 y). There was a comparable range in body fat within each group (control group: 11-34%; PKU group: 10-34%). The mean REE was similar between the male and female children with PKU (5300 +/- 757 and 4703 +/- 1024 kJ/24 h, respectively) and the control subjects (5306 +/- 969 and 5164 +/- 701 kJ/24 h, respectively). The children with PKU had an REE similar to that predicted from control data (males 102.1 +/- 7.8% of predicted and females 100.2 +/- 8.5% of predicted). This study found no evidence of a reduced REE or of increased weight in children with PKU.
Adolescent↗
A model for vicilin solubility at mild acidic pH, based on homology modelling and electrostatics calculations.
The crystallographic structures of jack bean canavalin and French bean phaseolin have been used to construct a homology model of the storage vicilin of cocoa. Reported molecular weights for cocoa storage protein subunits correlate with proteolysis at the site of a large hydrophilic insert in the mature protein. Burial of the hydrophobic amino acids on trimer formation is a strongly conserved feature in the vicilin family. Histidine residues also sit at the monomer-monomer interfaces of the trimer and are likely to contribute to the decreased solubility of cocoa vicilin at mild acidic pH, which is generally considered to be caused solely by aggregation near to the isoelectric point. Electrostatic calculations suggest that such an arrangement of histidine residues in the absence of specific counterion binding will not favour the particular geometry of trimer formation below neutral pH. Higher order aggregates that do not exclude histidine charge from the solvent may be favoured, aiding the precipitation of cocoa vicilin at mild acidic pH. This suggestion is considered for the vicilin family. The hypothesis could contribute to an understanding of the pH and ionic strength dependence of vicilin solubility in vitro, and possibly of the behaviour of vicilins in the seed storage environment.
Amino Acid Sequence↗
Blocking antibody assay for confirmation of urogenital Chlamydia infection.
We evaluated the Syva MicroTrak Chlamydia Blocking Antibody Assay as a confirmatory assay for the detection of Chlamydia trachomatis in urogenital specimens. During a 5-month period, 109 positives were obtained (4.9%) by the MicroTrak II Enzyme Immunoassay as implemented with the Syva XL automated enzyme immunoassay instrument. Of 98 evaluable samples, 92 (93.9%) were confirmed as positive by the blocking assay, and 3 blocking-negative samples had organisms detected by direct fluorescent-antibody analysis (blocking sensitivity, 96.8%). We found that direct fluorescent-antibody analysis of samples with a specimen-to-cutoff absorbance ratio of < or = 2.0 was a reasonable confirmation alternative and was more cost-effective than the blocking assay.
Adult↗
Tutorial software for clinical chemistry incorporating interactive multimedia clinical cases.
We have developed computer-based clinical case histories incorporating multimedia elements to aid the learning of medicine in a problem-based manner. Topics have been developed in the specialty of Clinical Biochemistry but the approach used is suitable for any branch of clinical medicine. Each topic has material aimed at medical students and also postgraduate candidates for professional examinations. A browser program is also incorporated. Emphasis is made on interaction through the case and modeling of real-life decisions in diagnosis and treatment. Advantages of the program are self-paced learning, assessment of understanding, feedback, and emphasis on deep understanding of the basic physiological and biochemical processes underlying clinical problems.
Chemistry, Clinical↗
Pediatric pain, trauma, and memory.
We review new research on childhood pain and trauma. We begin with studies on the expression and measurement of pain, pain management, recurrent abdominal pain, and brief and long-term memory of injury and medical procedures. We then review research on the impact of children's witnessing of pain in others as a result of injury or violence and children's experience of natural and man-made disasters. Finally we consider the links between pain, trauma, and memory and discuss our recommendations for the next steps to be taken.
Abdominal Pain↗
Development, characterization, and application of monoclonal antibodies to the native and synthetic beta COOH-terminal portion of human chorionic gonadotropin (hCG) that distinguish between the native and desialylated forms of hCG.
Although the pregnancy hormone hCG has been extensively mapped immunochemically, few monoclonal antibodies have been produced to the unique COOH-terminal region of its beta-subunit (beta CTP). We now report the development and characterization of five such monoclonal antibodies. Three of these antibodies were developed to the synthetic peptide analog of the hCG beta-(109-145) region coupled to diphtheria toxoid, and two antibodies to a conjugate of bovine thyroglobulin and the peptide hCG beta-(115-145) prepared from hCG with its carbohydrate moieties intact. The monoclonal antibodies raised against the synthetic peptide bound hCG, desialylated hCG, and synthetic peptide to a similar extent, whereas antibodies generated to the natural hCG peptide did not bind to the synthetic peptide analog of the COOH-terminal peptide (beta CTP) region or to desialyated hCG. These new monoclonal antibodies could distinguish between native and desialyated hCG in liquid phase immunoassays as well as by Western blots. They are highly specific reagents for such Western blotting and were used for studies of a crude human pituitary gonadotropin preparation to demonstrate that it contained intact hCG beta without the internal peptide bond cleavages found in the subunit present in human blood and urine. Competition experiments using combinations of monoclonal antibodies and rabbit anti-beta CTP antiserum demonstrated that two epitopes exist within the beta-(115-145) region of hCG, one of which depends on the presence of carbohydrate. In summary, the new monoclonal hCG beta CTP antibodies reported here can 1) discriminate between native and desialylated hCG, 2) identify hCG and nicked hCG on Western blots, 3) provide an immunoaffinity purification tool for hCG, and 4) bind to two distinct epitopes on the beta CTP.
Animals↗
Sensible drinking.
Although it is rare to find people willing to talk seriously about sensible smoking or sensible heroin-injection, the concept of sensible drinking is now sufficiently well established to merit debate beyond the specialists who have so far been interested in promoting or opposing it. The purpose of this article is to take a fresh look at sensible drinking as a stimulus to encouraging that wider debate.
Alcohol Drinking↗