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Biomedical subjects

J Lafferty

Publications and source records attributed to J Lafferty.

At least 19 recordsLinked to original sources
PubMed2001

Hb H hydrops foetalis syndrome: a case report and review of literature.

Haemoglobin H (Hb H) disease is caused by deletion or inactivation of three alpha-globin genes, leaving only one intact and active alpha-globin gene. People with Hb H disease usually have moderate anaemia, but are generally thought to be asymptomatic. Some Hb H disease patients require transfusions, and there are reports of fetuses with Hb H disease who have severe anaemia in utero resulting in fatal hydrops foetalis syndrome. We now report a case of Hb H hydrops foetalis syndrome, caused by the inheritance of a hitherto novel alpha-globin gene point mutation (codon 35 TCC-->CCC or Serine-->Proline) and an alpha-thalassaemia deletion of the Filipino type removing all zeta-alpha-globin genes on the other chromosome 16. The infant was delivered prematurely because of pericardial effusion and fetal distress, and was found to have severe anaemia and congenital anomalies. A review of the relevant literature on this syndrome is presented, and serves to underscore the phenotypic variations of Hb H disease and the need for surveillance for this condition among newborns and genetic counselling in communities with a high proportion of at-risk populations.

Base Sequence↗
PubMed1999

Effect of hemodialysis on the signal-averaged electrocardiogram.

The presence of late potentials (LPs) on signal-averaged electrocardiography (SAECG) is predictive of ventricular tachycardia. The effect of hemodialysis (HD) on SAECG has not been well studied. SAECG was evaluated in 28 patients with chronic renal failure immediately before and after HD. In each SAECG, QRS duration, low-amplitude signal duration (LASd), and root-mean-square voltage of the terminal 40 milliseconds of the QRS (RMS40) were measured. To evaluate the effect of fluid removal on SAECG, the last 12 patients were studied during two different HD sessions, one with and one without fluid removal. Two-dimensional echocardiography was performed before and after HD on these 12 patients. At baseline, four patients met the criteria for LPs on SAECG. Only one patient met the criteria for LPs on SAECG after HD. After HD, the mean LASd decreased (28.3 +/- 12.9 to 24.9 +/- 10.1 milliseconds; P = 0.041) and RMS40 increased (63.0 +/- 56.9 to 79.0 +/- 59.2 microV; P = 0. 006). Among the 12 patients who underwent HD with and without fluid removal, left ventricular end-diastolic dimension decreased with (5. 4 +/- 0.6 to 5.1 +/- 0.6 cm; P = 0.024) but not without fluid removal (5.2 +/- 0.3 to 5.1 +/- 0.4 cm; P = not significant [NS]). RMS40 improved with (43.8 +/- 23.1 to 53.2 +/- 22.6 microV; P = 0. 03) but not without fluid removal (51.0 +/- 26.5 to 51.5 +/- 24.2 microV; P = NS). A significant negative correlation was found between change in body weight and change in RMS40 parameter (r = 0. 456; P = 0.0381). SAECG parameters are abnormal in a significant proportion of patients with chronic renal failure and improve with HD despite electrolyte and other proarrhythmic changes. Decreased left ventricular dimension because of fluid removal during HD is one possible explanation for this improvement.

Electrocardiography↗
PubMed1997

Proficiency testing of hemoglobinopathy techniques in Ontario laboratories.

The Laboratory Proficiency Testing Program has been in effect for 20 years. During the past 6 years, samples were distributed for screening, investigation, and identification of hemoglobinopathies to test laboratory proficiency. Six samples for hemoglobin (Hb) S screening were distributed to from 37 to 163 laboratories that perform screening tests for sickle cell disease, and 10 samples were distributed to from 52 to 71 laboratories that perform Hb electrophoresis. Assessment of unacceptable results was based on clinical significance of the errors; educational follow-up was implemented to address these results. Most participants demonstrated acceptable performance. The error rates for sickle cell screening were 2.7% to 19.7%; the poorest performance was noted for Hb SC disease. The error rates for Hb electrophoresis were 1.4% to 36.8%; the poorest performance was noted in the investigation of Hb H disease and alpha-thalassemia trait. Improved survey performance was observed in the screening for Hb S trait and in the investigation of Hb H disease, which illustrates the benefits of proficiency testing and its positive effect on laboratory services.

Certification↗
PubMed1996

Epidemiology of fecal incontinence: the silent affliction.

OBJECTIVE: Fecal incontinence represents an embarrassing social problem, the magnitude of which remains largely unknown. The present study prospectively examined the prevalence and demographic distributions of fecal incontinence. METHODS: demographic data, in addition to information regarding the reason for visit, bowel habits, and the frequency, type, and severity of fecal incontinence, were collected from individuals at the time of visits to their primary care physician or gastroenterologist. RESULTS: Eight hundred and eighty-one individuals 18 yr or older were included in the analysis. The overall prevalence of fecal incontinence was 18.4%. When stratified by frequency, 2.7, 4.5, and 7.1% of participants admitted to incontinence daily, weekly, or once per month or less, respectively. Incontinence increased progressively with age and was 1.3 times more common in males than females. Only one-third of individuals with fecal incontinence had ever discussed the problem with a physician. CONCLUSIONS: The prevalence of fecal incontinence appears to be more common than previously appreciated. Moreover, only a minority with a physician. It would seem important to more actively pursue this "silent affliction" particularly in patients who do not readily volunteer this information.

Adolescent↗
PubMed1995

Identification of a new high oxygen affinity hemoglobin variant: Hb Aurora [beta 139(H17) Asn-->Tyr].

A 73-year-old female of Dutch descent was referred for investigation of a high oxygen affinity hemoglobin variant. The beta-globin gene was amplified using the polymerase chain reaction. Direct nucleotide sequencing of the polymerase chain reaction amplified DNA revealed that she is heterozygous for a novel beta-globin gene mutation at codon 139, AAT-->TAT. The resulting hemoglobin variant has been designated Hb Aurora [beta 139 (H17) Asn-->Tyr].

Aged↗
PubMed1994

Hemoglobinopathies: three illustrative case studies.

Three cases studies from the Regional Hemoglobinopathy Laboratory at St. Joseph's Hospital in Hamilton are presented. These cases demonstrate the diagnostic value of a comprehensive hemoglobinopathy screen, family studies, and appropriate clinical information in solving complex hemoglobinopathy problems. The first case is a 79-year-old woman found to have small amounts of an unknown hemoglobin migrating electrophoretically in the position of hemoglobin S. The second case describes a boy of Greek extraction with a thalassemic blood picture but otherwise normal hemoglobinopathy screen. The third case involves a 70-year-old man with a previously normal hemoglobinopathy screen who subsequently showed evidence of alpha thalassemia.

Adult↗
PubMed1992

The clinical significance of hemoglobinopathies in the Hamilton region: a twenty-year review.

Between 1970-1990, the Laboratory tested 38,391 specimens for hemoglobinopathies, of which 7,935 were positive. The major abnormalities detected were beta thalassemia trait (4,688), alpha thalassemia trait (1,248) and sickle cell trait (847). Clinically significant hemoglobinopathies detected were Hemoglobin H disease (100), sickle cell disease (67) and sickle cell Hemoglobin C disease (79). Hemoglobinopathies are therefore common in the Hamilton area as a reflection of the cultural diversity of area citizens. Of the 49 patients with thalassemia without documented iron deficiency, 8 (16%) received iron therapy for a variable period of time and 3 were investigated for gastrointestinal blood loss. Hemoglobin abnormalities cause or have the potential to cause clinical disease and they can, if not detected, result in unnecessary iron therapy or gastrointestinal investigation.

Hemoglobin C Disease↗
PubMed1991

Preferential T-cell receptor beta-chain variable gene use in myelin basic protein-reactive T-cell clones from patients with multiple sclerosis.

Multiple sclerosis is an autoimmune disease in which T lymphocytes reactive to myelin basic protein (BP) could play a central role. T cells specific for BP were cloned from the blood of multiple sclerosis patients and normal individuals, and expression of T-cell receptor variable region genes was analyzed. A remarkable bias for use of beta-chain variable region (V beta) 5.2 and, to a lesser extent, V beta 6.1 was seen among BP-specific clones from patients but not from controls. The preferential use of V beta 5.2 for BP recognition did not reflect altered expression of this V beta in the peripheral repertoire. Interestingly, shared V beta 5.2 usage was apparent for clones specific for different BP determinants, even when derived from the same individual. The concurrent demonstration by others (J. R. Oksenberg, M. A. Panzara, A. B. Begovich, H. Erlich, R. Murray, M. Sherritt, S. Stuart, C. C. Bernard, and L. Steinman, personal communication) that T cells within demyelinating areas of multiple sclerosis brains preferentially express V beta 5.2 and V beta 6.1 suggests that the BP-specific clones derived from blood may be relevant to disease pathogenesis. These findings may have important implications for the treatment of multiple sclerosis.

Base Sequence↗
PubMed1991

A method for production of antibodies to human T-cell receptor beta-chain variable regions.

Mouse T-cell hybridomas bearing human V beta elements were produced by transfection of human/mouse hybrid T-cell receptor beta-chain genes into a mouse T-cell hybridoma lacking an endogenous beta-chain gene. These hybridomas were entirely mouse in origin except for the human V beta region. These cells were used to immunize mice against human V beta elements. Mouse monoclonal antibodies have thus been generated against human V beta 13.1 and -13.2. We expect that the method outlined in this paper will be useful in the production of monoclonal antibodies specific for other human V beta or V alpha elements.

Animals↗
PubMed1984

Assessment of alpha-adrenergic receptor subtypes in isolated rat aortic segments.

The postsynaptic alpha-adrenoceptors in the isolated rat aorta have been characterized according to the sensitivity of the tissue to selective alpha 1- and alpha 2-adrenoceptor agonists and antagonists. The potency (-log EC50) order of the non-selective alpha-agonist norepinephrine and relatively selective agonists was as follows: norepinephrine (alpha 1 = alpha 2; 7.30); clonidine (alpha 2 greater than alpha 1; 7.01); phenylephrine (alpha 1 greater than alpha 2; 6.99), SK & F 89748--A (alpha 1 greater than alpha 2; 6.65); BHT-920 (alpha 2 much greater than alpha 1; 5.56) and M-7 (alpha 2 greater than alpha 1; 4.66). The isolated rat aorta was 12-200-fold more sensitive to the alpha 1-adrenoceptor agonists phenylephrine and SK & F 89748-A, than to the alpha 2-agonists, BHT-920 and M-7. Prazosin is 245-1259-fold more potent than rauwolscine as an antagonist of contractions induced by various alpha 1- and alpha 2-agonists in the rat aorta. These data indicate that constriction of the smooth muscle of the rat aorta to alpha-adrenergic agonists is mediated through alpha 1- but not alpha 2-adrenoceptors.

Adrenergic alpha-Agonists↗
PubMed1984

Development of an affinity ligand for purification of alpha 2-adrenoceptors from human platelet membranes.

Human platelets contain alpha 2-adrenoceptors which are negatively coupled to the enzyme adenylate cyclase. In order to better understand the interaction of this subtype of alpha receptor with this key enzyme, we have initiated a program to isolate and characterize the alpha 2-adrenoceptor. This report describes the synthesis and biological characterization of a series of molecules that were prepared as affinity ligands for this purpose. The best of these is 9-(allyloxy)-6-chloro-3-methyl-2,3,4,5-tetrahydro-1H-3-benzazepine (SK&F 101253). This compound is an alpha 2-adrenoceptor antagonist, which was obtained by synthetic modification of 6-chloro-3-methyl-2,3,4,5-tetrahydro-1H-3-benzazepine (SK&F 86466), a novel antagonist with high affinity for the alpha 2-receptor.

Affinity Labels↗
PubMed1976

Intracranial responses to PEEP.

Elevated intrathoracic pressure due to positive end-expiratory pressure (PEEP) has the potential for increasing intracranial pressure (ICP) and reducing arterial blood pressure (BP). Such changes could critically reduce cerebral perfusion pressure (CPP = BP - ICP), This possibility was investigated in 15 cats with artificially-produced expanding intracranial masses (intracranial balloon). The interrelationships among ICP and central venous and arterial pressures were observed during application and removal of graded levels of PEEP (5, 10, 15 cm H2O). The electroencephalogram and pupillary diameters were monitored. At various levels of ICP, nine of the cats were given oleic acid intravenously to embolize the lung and cause pulmonary dysfunction. In cats not given oleic acid, PEEP caused a maximal reduction in cerebral perfusion pressure of 45 +/- 4 torr(SEM), accompanied by variable changes in ICP. PEEP application in the absence of oleic acid embolization of the lungs caused electroencephalographic abnormalities in 77% of these cats, while pupillary diameters increased in 56%. Animals embolized wwith oleic acid had significantly less (P less than .001) severe CPP reductions (mean 21 +/- 4 torr) than did the non-embolized animals, and developed no EEG change due to PEEP. However, increases in pupillary diameter still occurred in 33% of cats given oleic acid when PEEP was applied. In 82% of the PEEP applications (n = 44) in both experimental groups only insignificant increases in intracranial tension occurred (average peak ICP gain less than 1.5 torr). Abrupt increases in ICP exceeding 11 torr (15 cm H2O) occurred in four animals in each group. This happened most frequently (63 per cent) when the intracranial tension before PEEP was above 15 torr. Sudden removal of or reduction in PEEP was accompanied by increases in arterial and intracranial pressures in both groups, although this response was attenuated in the cats given oleic acid. The results indicate a potential for PEEP to evoke neurolgic complications in patients who have intracranial disease and that the presence of pulmonary disease may attenuate these deleterious side effects. Monitoring of neurologic function as well as blood-gas and cardiovascular effects of PEEP in patients who have intracranial disease is suggested.

Animals↗
PubMedDate not supplied

Reevaluation of the ammonium sulfate assay for DNA antibody.

The ammonium sulfate assay has recently come under criticism for alleged inability to detect low avidity antibody to DNA. The results of this study verify that a small percentage of antibody binding is not detected when this assay is performed under the conditions generally used. However, when the values obtained by the ammonium sulfate assay were compared to those obtained by other assays on sera of known avidity for DNA, it was concluded that ammonium sulfate does not selectively dissociate low avidity antibody from DNA. Conditions of incubation buffer and duration, pH, concentration of reactants, and molecular weight of the antigen are described for optimal detection of DNA antibody by the ammonium sulfate assay.

Ammonium Sulfate↗