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Biomedical subjects

J Pollock

Publications and source records attributed to J Pollock.

At least 55 records · Page 3Linked to original sources
PubMed1993

Maternal CW alloimmunization.

The Winnipeg Rh Laboratory has reviewed its experiences with maternal CW alloimmunization. From September 24, 1956, to March 31, 1992, 12 women with significant CW alloimmunization underwent 18 pregnancies. In 3 (4 pregnancies) the antibody, despite its strength, was 'naturally occurring' (i.e. there was no known exposure to CW-positive red cells). The remaining 9 women (14 pregnancies) had CW-positive husbands. Two had CW-negative babies and a third infant, probably CW negative, was stillborn and macerated at 43 weeks gestation. Eleven babies were CW positive and had hemolytic disease of the newborn (HDN), with antiglobulin-positive red cells. Five did not require treatment; 2 needed phototherapy only, and 4 (born between 1956 and 1963) required exchange transfusions. No anti-CW screening was carried out until 1977; thereafter it was sporadic, 11 of 51 screening red cells being CW positive in the 39-month period ending March 31st, 1992. From November 1, 1977, to March 31, 1992, 24 women (30 pregnancies, 31 conceptuses) with insignificant anti-CW alloantibodies were identified. Extrapolating these figures to the entire period from September 24, 1956, to March 31, 1992, we estimate that at least 430 women (at least 573 pregnancies) were CW alloimmunized, most of the antibodies being 'naturally occurring'. Only 2% of the conceptuses were CW positive and affected; none were severely affected. Anti-CW is relatively common, occurring in about 1 pregnant Manitoban woman in 1,100. On very rare occasions (11 times in Manitoba in 36 years and 5 months) anti-CW HDN occurs which, although not severe, may end in kernicterus with brain damage or neonatal death unless it is detected promptly and treated appropriately.

Coombs Test↗
PubMed1992

Expression and genomic structure of the genes encoding FdI, the major allergen from the domestic cat.

The genes encoding chain 1 (Ch1) and chain 2 (Ch2) of the major allergen of the domestic cat, Felis domesticus I, have been analyzed by genomic cloning and by polymerase chain reaction (PCR). Ch1 has two potential leader sequences, designated A and B. Analysis of a genomic clone encoding Ch1 demonstrated that one structural gene contains sequences corresponding to both leaders, which utilize different Met start codons. PCR analysis showed that genes encoding Ch1 and Ch2 are co-expressed in both the salivary glands and the skin, and that leader sequence A of Ch1 is utilized preferentially in both tissues. Ch2 was shown to have two dominant forms that are differentially expressed in the aforementioned tissues. The long form (Ch2L), composed of 92 amino acids (aa), is preferentially expressed in the salivary glands, while the short form (Ch2S), composed of 90 aa, is preferentially expressed in the skin. There is minor sequence polymorphism in both forms of Ch2. A genomic clone for Ch2 only contained sequences for Ch2S, suggesting that Ch2L is encoded by an exon not contained within this genomic clone.

Allergens↗
PubMed1991

Cloning and sequencing of Lol pI, the major allergenic protein of rye-grass pollen.

We have isolated a full length cDNA clone encoding the major glycoprotein allergen Lol pI. The clone was selected using a combination of immunological screening of a cDNA expression library and PCR amplification of Lol pI-specific transcripts. Lol pI expressed in bacteria as a fusion protein shows recognition by specific IgE antibodies present in sera of grass pollen-allergic subjects. Northern analysis has shown that the Lol pI transcripts are expressed only in pollen of rye-grass. Molecular cloning of Lol pI provides a molecular genetic approach to study the structure-function relationship of allergens.

Allergens↗
PubMed1991

Intravenous drug abuse causes Rh immunization.

Intravenous drug abuse causes many health problems. From March 1989 to January 1990 of 27 Rh-negative women (28 pregnancies) referred to our centre, 4 women (5 pregnancies) were Rh immunized due to the sharing of needles and blood with their Rh-positive partners. Severe hydrops was present in 4 of their 5 fetuses when they were first seen at 17-35 weeks of gestation. Only the fetus first seen at 35 weeks survived. That infant was moribund at birth and now has evidence of leukomalacia and porencephaly. The fifth fetus, not hydropic, required two intravascular fetal transfusions in order to survive. A fifth woman, immunized in a similar manner, had a spontaneous abortion. These fetuses represent some of the earliest and severest examples of hydrops fetalis ever seen at our centre. The severity of their fetal hemolytic disease is probably due to the fact that their mothers' exposure to Rh(D) antigen by blood sharing was continuous and ongoing. Because of their aberrant behaviour, these women have suffered irreversible reproductive damage.

Abortion, Spontaneous↗
PubMed1991

Sequence polymorphism of Amb a I and Amb a II, the major allergens in Ambrosia artemisiifolia (short ragweed).

Two of the major allergens in the pollen of short ragweed are Amb a I and Amb a II (formerly antigen E and antigen K, respectively). The genes for Amb a I and Amb a II have recently been cloned, and it was shown that Amb a I is a family of proteins with at least three distinct polymorphic family members. This study addresses the number of individual Amb a I and Amb a II family members, the polymorphism in each family member and the expression of these genes in ragweed plants from different geographical locations. This work led to the cloning and characterization of a fourth Amb a I family member, designated Amb a I.4.

Allergens↗
PubMed1991

Naloxone prevents and blocks the emergence of neuroleptic-mediated oral stereotypic behaviors.

A commonly used animal model for tardive dyskinesia is the oral stereotypy that is expressed by a challenge dose of a dopamine agonist after daily administration of dopamine antagonists (neuroleptics). In the first of two experiments the expression of this dopamine agonist-induced oral stereotypy was prevented by the concomitant administration of the opiate antagonist naloxone. In a second experiment, if the stereotypy was allowed to be expressed, it could be blocked by the administration of naloxone. To the extent that the effects of chronic neuroleptic treatment in rats is a model for tardive dyskinesia, the results suggest that administration of naloxone can both prevent and block the dyskinetic syndrome associated with neuroleptic use.

Animals↗
PubMed1990

Chick tropoelastin isoforms. From the gene to the extracellular matrix.

Studies from several laboratories have demonstrated the existence of multiple tropoelasting mRNAs and protein isoforms. The present study was designed to examine the developmental expression of a specific tropoelastin mRNA, its encoded isoform, and the fate of that isoform in the extracellular matrix. A chick genomic DNA library was screened with a chick tropoelastin cDNA. Seven unique, overlapping clones spanning 39 kilobases were isolated. A synthetic oligonucleotide complementary to a variable tropoelastin mRNA sequence was used to identify a 1.5-kilobase PstI-BamHI genomic fragment. Nucleotide sequence data revealed that the putative exon was surrounded by intron sequences possessing canonical splice sites at the exon/intron borders. Using both immunologic and molecular probes specific to the tropoelastin isoform and mRNA, quantitative protein and RNA analyses were performed. Results demonstrate that total tropoelastin mRNAs increased significantly during aortic embryogenesis whereas the amount of mRNA containing the variable exon remained relatively constant. The amount of total tropoelastins within the same developmental period reflect the level of total tropoelastin mRNA. The amount of the tropoelastin isoform containing the variable exon essentially mirrored the corresponding mRNA with the exception that a decrease in the isoform at day 15 was not seen in the mRNA level. Immunoelectron micrographs of 13-day chick aortic tissue using both total and isoform-specific antisera showed ultrastructural localization to definable elastic fibers. Antibodies to the variable tropoelastin isoform occurred preferentially at sites where elastic fiber microfibril structures were evident.

Amino Acid Sequence↗
PubMed1990

Pharmacologic evidence for nociception resulting from noncontingent "rewarding" brain stimulation.

Prolonged noncontingent electrical stimulation to rewarding brain sites will elicit escape behavior in rats. This study was designed to determine if this escape behavior is reinforced by the termination of a nociceptive stimulus or reinforced by the rewarding effects of the onset of the next stimulus. In the present experiment we determined the effects of the hyperalgesic naloxone (NX) and the analgesic ethylketocyclazocine (EKC) on the threshold for escape from electrical brain stimulation to the medial forebrain bundle-lateral hypothalamic area (MFB). Results indicate that EKC (0.5-1.0 mg/kg) raises the escape threshold, whereas NX (8.0-16.0 mg/kg) lowers the escape threshold, suggesting that escape from electrical brain stimulation to the MFB is the result of the nociceptive quality of stimulation and not the result of the rewarding effects of the onset of stimulation.

Analgesics, Opioid↗
PubMed1989

Evidence for the role of dopamine D1 receptors in morphine induced stereotypic behavior.

In the course of studying the effects of morphine on the escape from electrical stimulation to the rat medial forebrain bundle, we observed that a combination of low doses of morphine and stimulation, neither of which caused stereotypy in the rat, resulted in marked stereotypic behavior that was similar to that seen with high doses of morphine alone. This behavior could be blocked by either naloxone or by the D1 antagonist SCH 23390, but not by the D2 antagonist raclopride. Furthermore, the stereotypy caused by chronically administered high doses of morphine was blocked by naloxone and the D1 antagonist. These results strongly implicate the role of dopamine D1 activation in morphine-induced stereotypies.

Animals↗
PubMed1986

Studies on haematocrit in peripheral arterial disease.

Haematocrit is often elevated in peripheral arterial disease, and is an important determinant of blood viscosity and of platelet behaviour. We have studied the relationships of haematocrit to claudication, smoking habit, calf blood flow, platelet aggregation in whole blood, and the late complications of aortic bifurcation grafts. In 31 claudicants, blood viscosity, haematocrit and fibrinogen levels were significantly higher compared to 50 controls (p less than 0.01). However this was largely explained by a higher prevalence in claudicants of cigarette-smoking, which is associated with increased blood viscosity, haematocrit and fibrinogen levels. In 8 stable claudicants with high-normal haematocrit (mean 0.50), venesection reduced haematocrit to low-normal levels (mean 0.44). Resting calf blood flow was unchanged: peak flow increased slightly (17%) but oxygen delivery (peak flow X haemoglobin concentration) was unchanged. Spontaneous platelet aggregation in whole blood was studied using a single platelet counting method: the increase in haematocrit in patients with claudication was not associated with a significant increase in aggregation, and a negative association of haematocrit and aggregation was observed. In a preliminary retrospective study of patients with late complications of aortic bifurcation grafts, significantly higher haematocrits prior to operative were found compared to controls who had not returned to the clinic. Further prospective studies are required to assess the significance of haematocrit in peripheral arterial disease, and to determine whether any adverse effects are due to associations with smoking, rheology or platelet behaviour.

Adult↗
PubMed1986

Membranoproliferative glomerulonephritis, type II and partial lipodystrophy in an adult.

Membranoproliferative glomerulonephritis, type II is commonly seen in patients with the rare disorder, partial lipodystrophy. This disease complex, although usually seen in the pediatric or young adult age group, should be considered in older patients with characteristic loss of facial fat and signs and symptoms of nephritis. A case of partial lipodystrophy with membranoproliferative glomerulonephritis, type II in an older patient demonstrates the characteristic ultrastructural renal findings.

Basement Membrane↗
PubMed1986

A V1-like receptor mediates vasopressin-induced flank marking behavior in hamster hypothalamus.

A vasopressin-sensitive mechanism within the medial preoptic area-anterior hypothalamus (MPOA-AH) appears to be essential for expression of a complex behavior involved in olfactory communication in Golden hamsters called flank marking. The present study investigated whether the induction of flank marking by arginine-vasopressin (AVP) within the MPOA-AH is mediated by a receptor that is more similar to the vasopressor (V1) or the antidiurectic (V2) AVP receptor. Adult male hamsters were anesthetized and implanted with a 26 gauge guide cannula stereotaxically aimed at the MPOA-AH and then microinjected with analogs of vasopressin, oxytocin, and selective V1 and V2 antagonists. Hamsters were tested for flank-marking behavior during a 5 or 10 min observation period following the injection of peptide in a vehicle of 100 nl of saline. None of the 15 analogs of AVP and oxytocin produced more flank marking than the 50.8 +/- 16.2 and 76.8 +/- 4.4 (mean +/- SEM; n = 4) flank marks observed following injection of AVP at the 1 or 10 ng dose, respectively. The number of flank marks produced by each analog was found to be highly related to the pressor activity of that analog at both the 1 ng (rho = +0.74, p less than 0.01) and 10 ng (rho = +0.82, p less than 0.01) doses. In contrast, no statistically reliable relationship between flank marking and the antidiuretic activity of these analogs was found at either dose (1 ng: rho = +0.07, p greater than 0.05; 10 ng: rho = +0.10, p greater than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗