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A Morrison

Publications and source records attributed to A Morrison.

At least 37 records · Page 2Linked to original sources
PubMed1992

A simple method of generating axenic derivatives of Dictyostelium strains.

We describe a generally applicable method of adapting Dictyostelium from growth on a bacterial food source to axenic growth. Cells are initially selected by growth on a plastic substratum but subsequently acquire the ability to grow in suspension culture. These strains can be transformed efficiently by DNA-mediated gene transfer.

Animals↗
PubMed1992

The incidence of total hip replacement in orthognathic surgery patients receiving short-term steroid therapy.

It is well known that long-term corticosteroid therapy can lead to avascular necrosis of the femoral head. There is suspicion among orthopedic surgeons that short-term, high-dose steroid use poses similar risks. The records of 2,773 patients (1,497 who had total hip replacement and 1,276 who had orthognathic surgery) were retrospectively reviewed. No hip replacements had been done in the orthognathic surgery group and none of the patients in the total hip replacement group had undergone orthognathic surgery. The use of short-course, systemic corticosteroids to reduce postoperative swelling in orthognathic surgery did not seem to cause avascular necrosis of the femoral head.

Adrenal Cortex Hormones↗
PubMed1992

Ataxia-telangiectasia: linkage analysis of chromosome 11q22-23 markers in Turkish families.

To further pinpoint the location of the genes for ataxia-telangiectasia on the long arm of chromosome 11, we performed linkage analysis and analysis of recombinants of genetic haplotypes on 14 Turkish families with ataxia-telangiectasia, 12 of which were consanguineous. These studies used more than 25 polymorphic genetic markers spanning a region of the long arm of chromosome 11 that is larger than 50 cM. Seven markers gave significant LOD scores to AT: CJ5, DRD2, CJ208, S144, CD3E, PBGD, and S147, as did haplotypes created with pairs of markers DRD2/CJ5 and S144/CJ208, giving recombination fractions (theta) of 0.00, 0.00, 0.05, 0.08, 0.03, 0.09, 0.07, 0.00, and 0.06, respectively. Monte Carlo analysis of these 14 Turkish families indicated the best location for a single AT gene to be within a 6 cM sex-averaged (3 cM male-specific) interval defined by STMY and CJ77; this was three times more likely than the next most likely location (peak III) at the DRD2 locus. The analysis also revealed a peak (peak II) between S147 and S133, which may represent the complementation group D gene. Recombinant analysis of haplotypes also localized an AT locus to the STMY-CJ77 interval. Taken together, these results suggest that at least two distinct AT loci exist (ATA and ATD) at 11q22-23, with perhaps a third locus, ATC, located very near to the ATA gene. This genetic heterogeneity further complicates plans to isolate the major ATA and ATC genes and to begin identifying AT carriers in the general population.

Ataxia Telangiectasia↗
PubMed1992

Attenuating the hypertensive response to laryngoscopy and endotracheal intubation using awake fibreoptic intubation.

Blood pressure and pulse rate measurements were recorded in 35 patients undergoing endotracheal intubation during general anaesthesia (Group A), and 35 patients who had an awake fibreoptic intubation under local anaesthesia (Group B). The mean arterial pressure in Group A rose by a mean of 35 mmHg immediately after intubation, compared with a mean fall of 9 mmHg in Group B. The mean pulse rate in Group A rose by 24 beats per minute (b.p.m.) immediately after intubation, compared with a rise of 3 b.p.m. in Group B. Both these differences were statistically significant (P less than 0.0001 and P less than 0.001 respectively, Mann Whitney U test). Postoperative discomfort was assessed 24 h later by means of linear analogue scales. There was a statistically higher mean score in relation to nose discomfort in Group B (P less than 0.002). Awake fibreoptic intubation successfully reduces the pressor response to endotracheal intubation in normotensive adults. It is suitable for use in those patients who are at risk from the pressor response.

Anesthesia, General↗
PubMed1992

Larval population dynamics in a community of nearctic Aedes inhabiting a temporary vernal pool.

The spatial distribution and preadult mortality patterns of 4 cohabiting species of Aedes mosquitoes were studied in a temporary vernal pool at Mt. Carmel, CT, from March to May 1990. The dominant species was Ae. stimulans (79.9%), followed by Ae. canadensis (10.7%), Ae. excrucians (7.5%) and Ae. cinereus (1.9%). First instar larvae of all species aggregated at the edge of the pool and then dispersed to deeper regions as they matured. Larval mortality was high, and the majority occurred during the first stadium (80.9% for Ae. canadensis, 88.9% for Ae. excrucians, 89.1% for Ae. stimulans and 90.0% for Ae. cinereus). A predatory chaobrid, Mochlonyx cinctipes, was implicated as the major mortality factor affecting larval populations.

Aedes↗
PubMed1991

Eukaryotic DNA polymerase amino acid sequence required for 3'----5' exonuclease activity.

We have identified an amino-proximal sequence motif, Phe-Asp-Ile-Glu-Thr, in Saccharomyces cerevisiae DNA polymerase II that is almost identical to a sequence comprising part of the 3'----5' exonuclease active site of Escherichia coli DNA polymerase I. Similar motifs were identified by amino acid sequence alignment in related, aphidicolin-sensitive DNA polymerases possessing 3'----5' proofreading exonuclease activity. Substitution of Ala for the Asp and Glu residues in the motif reduced the exonuclease activity of partially purified DNA polymerase II at least 100-fold while preserving the polymerase activity. Yeast strains expressing the exonuclease-deficient DNA polymerase II had on average about a 22-fold increase in spontaneous mutation rate, consistent with a presumed proofreading role in vivo. In multiple amino acid sequence alignments of this and two other conserved motifs described previously, five residues of the 3'----5' exonuclease active site of E. coli DNA polymerase I appeared to be invariant in aphidicolin-sensitive DNA polymerases known to possess 3'----5' proofreading exonuclease activity. None of these residues, however, appeared to be identifiable in the catalytic subunits of human, yeast, or Drosophila alpha DNA polymerases.

Amino Acid Sequence↗
PubMed1991

Cloning DPB3, the gene encoding the third subunit of DNA polymerase II of Saccharomyces cerevisiae.

DNA polymerase II purified from Saccharomyces cerevisiae contains polypeptides with apparent molecular masses of greater than 200, 80, 34, 30 and 29 kDa, the two largest of which (subunits A and B) are encoded by the essential genes POL2 and DPB2. By probing a lambda gt11 expression library of yeast DNA with antiserum against DNA polymerase II, we isolated a single gene, DPB3, that encodes both the 34- and 30-kDa polypeptides (subunit C and C'). The nucleotide sequence of DPB3 contained an open reading frame encoding a 23-kDa protein, significantly smaller than the observed molecular masses, 34- or 30-kDa, which might represent post-translationally modified forms of the DPB3 product. The predicted amino acid sequence contained a possible NTP-binding motif and a glutamate-rich region. NTP-binding motif and a glutamate-rich region. A dpb3 deletion mutant (dpb3 delta) was viable and yielded a DNA polymerase II lacking the 34- and 30-kDa polypeptides. dpb3 delta strains exhibited an increased spontaneous mutation rate, suggesting that the DPB3 product is required to maintain fidelity of chromosomal replication. Since a fifth, 29-kDa polypeptide was present in DNA polymerase II preparations from wild-type cell extracts throughout purification, the subunit composition appears to be A, B, C (or C and C') and D. The 5' nontranscribed region of DPB3 contained the MulI-related sequence ACGCGA, while the 0.9-kb DPB3 transcript accumulated periodically during the cell cycle and peaked at the G1/S boundary. The level of DPB3 transcript thus appears to be under the same cell cycle control as those of POL2, DPB2 and other DNA replication genes. DPB3 was mapped to chromosome II, 30 cM distal to his7.

Amino Acid Sequence↗
PubMed1991

Leishmania donovani chagasi: new clinical variant of cutaneous leishmaniasis in Honduras.

During surveillance for endemic visceral leishmaniasis on an island off the Pacific coast of Honduras, an unusual form of cutaneous leishmaniasis was encountered. By clinical and laboratory criteria, 17 cases were identified over 5 months; children aged 4 to 15 years were primarily affected. Lesions were generally few in number, small, always papular, and non-ulcerative, even when present for several years. Patients with skin lesions seemed otherwise healthy and were well nourished. Montenegro skin tests with Leishmania mexicana and L major antigens were positive in 10 of 17 patients tested, and lesions from 9 patients were positive by culture. Since the summer of 1988, cases of atypical cutaneous leishmaniasis continue to occur on the island (8) as well as on the mainland of southern Honduras (23). A total of 9 parasite isolates from skin lesions, 4 from bone marrow of patients with kala-azar, and 2 from sandflies were identified as L donovani chagasi and were indistinguishable from one another by isoenzyme analysis.

Adolescent↗
PubMed1990

A third essential DNA polymerase in S. cerevisiae.

DNA polymerases I and III are essential for viability of S. cerevisiae. We have cloned and analyzed POL2, the gene encoding the catalytic subunit of the third nuclear DNA polymerase, DNA polymerase II. POL2 expressed a transcript of approximately 7.5 kb and contained a reading frame that encoded a protein of calculated Mr 255,649. The N-terminal half of the predicted protein displayed relatively weak similarity of sequence to eukaryotic DNA polymerases. Disruption of the coding sequence at midpoint led to viable, slowly growing cells, which yielded a truncated polypeptide with DNA polymerase II activity, free from subunits B or C. Deletion of the reading frame resulted in inviability and the dumbbell terminal morphology that typically follows arrest of DNA replication. We conclude that three DNA polymerases are essential in yeast and argue that all three are replicases, a possibility that challenges existing models of eukaryotic DNA replication.

Amino Acid Sequence↗
PubMed1990

Manipulation of the acute inflammatory response by dietary polyunsaturated fatty acid modulation.

Dietary polyunsaturated fatty acid modulation has been used as an anti-inflammatory strategy in experimental models of disease as well as in clinical trials. To elucidate the mechanisms underlying the anti-inflammatory effects of manipulating dietary polyunsaturated fatty acids, the in vivo effects of essential fatty acid (EFA) deficiency and (n-3) fatty acid supplementation were contrasted using a model of acute inflammation induced by the i.p. injection of zymosan into mice. Both diets led to a substantial decrease in tissue (n-6) fatty acid content. EFA deficiency was also characterized by the accumulation of (n-9) fatty acids, particularly 20:3 (n-9), the fatty acid that uniquely characterizes the deficiency state. Dietary (n-3) fatty acid supplementation led instead to marked increases in (n-3) fatty acids, especially 20:5 (n-3). With respect to the antiinflammatory effects of the two diets, EFA deficiency, but not (n-3) fatty acid supplementation, depleted levels of resident peritoneal macrophages. EFA deficiency was also more effective than (n-3) fatty acid supplementation in inhibiting the influx of polymorphonuclear neutrophils in response to zymosan. The effect of the two diets on the in vivo generation of leukotriene(LT)B also differed markedly. EFA deficiency completely inhibited the synthesis of LTB. Dietary (n-3) fatty acid supplementation, in contrast, reduced the production of LTB4 by only 50%. With (n-3) fatty acid supplementation LTB5 was produced. The more modest effect of (n-3) fatty acid supplementation in decreasing LTB4 generation was not due to blockade of the cyclooxygenase pathway. EFA deficiency, but not (n-3) fatty acid supplementation, was associated with the decreased synthesis of thromboxane. Although dietary fatty acid modulation has been shown to diminish platelet activating factor (PAF) synthesis, studies using the PAF receptor blocker, L659989, established that PAF was not a significant factor in the elicitation of leukocytes in this model of inflammation. In summary, the anti-inflammatory effect of EFA deficiency was more marked that that of dietary (n-3) fatty acid supplementation in acute inflammation. This difference in anti-inflammatory potential appeared to be due to either the greater effect of EFA deficiency in decreasing levels of resident peritoneal macrophages or in suppressing the in vivo generation of LTB4.

Acute Disease↗
PubMed1990

A photoactivatable probe for the Na+/H+ exchanger cross-links a 66-kDa renal brush border membrane protein.

Earlier studies on LLC-PK1 cells have demonstrated two pharmacologically distinct Na+/H+ exchangers in renal epithelia. In addition, the cDNA clone for the human Na+/H+ antiporter which is growth factor activatable has been isolated and expressed (Sardet, C., Franchi, A., and Pouyssegur, J. (1989) Cell 56, 271-280). We report here the synthesis of an amiloride analogue that can be photoactivated and labeled with 125I. This analogue covalently cross-links a 66-kDa protein of bovine renal brush border membranes. A rabbit polyclonal antibody that was directed against a 20-amino acid peptide of the cytoplasmic domain of its human Na+/H+ antiporter also gives a positive Western against 66-kDa protein of bovine brush border membranes. Thus, the photoactive probe may be helpful in the isolation and purification of the brush border Na+/H+ exchanger.

Affinity Labels↗
PubMed1990

Masturbation mimicking abdominal pain or seizures in young girls.

Five girls, 7 to 27 months of age, had masturbatory posturing that did not involve rubbing of the genitalia or copulatory movements. This activity was mistakenly attributed to abdominal pain or seizures, and prompted unnecessary diagnostic tests. The posturing began at 3 to 14 months and consisted of "leaning episodes" in which the suprapubic region was applied to a firm edge or the parent's knee in one patient, stiffening of the lower extremities in a standing or sitting position in the second patient, and stiffening of the lower extremities while lying on their sides or supine in three infant patients. The posturing was often accompanied by irregular breathing, facial flushing, and diaphoresis, and lasted less than a minute to hours at a time. Management consisted of convincing the parents of the harmless nature of the activity, which then lessened the reinforcing effect of their responses. The posturing subsided, in time, without medical or surgical treatment.

Abdominal Pain↗
PubMed1990

Synergism between hepatic injuries and a nonhepatotropic reovirus in mice. Enhanced hepatic infection and death.

Reovirus type 1, after intravenous inoculation in the adult mouse, is secreted via bile into the intestine in an infectious form. Although reovirus type 1 is rapidly removed from systemic circulation by the liver and the lung, very few hepatocytes express reovirus antigen during infection. In intestinal cells, reovirus replicates selectively in the crypts. This site preference may be due to active cell proliferation in the crypts. We hypothesized that the state of the cell may affect virus replication and tested this hypothesis by using chemical and surgical means to increase hepatic mitotic activity. Adult mice were treated with carbon tetrachloride or surgical trauma, inoculated with reovirus type 1 intravenously, and subsequently killed. Virus antigen was identified using a highly specific immunohistochemical technique. Liver sections were stained using immunoperoxidase with specific rabbit antireovirus antibody. Hepatotoxin and surgical trauma increase reovirus antigen detection in both Kupffer cells and hepatocytes. Only the sequential administration of CCl4 and virus caused mortality at doses sublethal for each alone. These data demonstrate a synergism between hepatic injury and reovirus which results in a significant increase in the magnitude of viral infection and contributes to mortality. Such synergism may be important in idiopathic liver disease.

Animals↗
PubMed1990

Renal cortical release of a specific macrophage chemoattractant in response to ureteral obstruction.

Acute ureteral obstruction results in a large influx of macrophages into the cortex and medulla of the obstructed kidney. We examined supernatants from short-term cultures of acutely obstructed and contralateral control renal cortices to determine whether differential production of a chemoattractant for macrophages could account for the cellular infiltrate observed in the obstructed kidney. Using a microchemotaxis assay, supernatants from obstructed renal cortex did demonstrate significantly more chemotactic activity for rat peritoneal macrophages than did supernatants from the contralateral kidneys. This activity showed a dose-response relationship with macrophage migration, peaked between 4 and 12 hours of obstruction, and declined with longer periods of obstruction. The activity was heat stable. It was retained by an octadecylsilane column, and eluted with methanol. Partitioning of the methanol fraction into aqueous and organic phases demonstrated significant activity in the organic phase. In summary, the acutely obstructed rat kidney releases a previously undescribed chemotactic factor that behaves as a lipid. This factor may account for the mononuclear cell infiltrate observed during obstruction.

Animals↗