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Biomedical subjects

J A Phillips

Publications and source records attributed to J A Phillips.

At least 19 recordsLinked to original sources
PubMed1992

A human interleukin 3 analog with increased biological and binding activities.

Human interleukin 3 (IL-3) variants generated by site-directed mutagenesis were analyzed in multiple biological and binding assays to identify residues critical for IL-3 activity. Two mutants carrying substitutions in the predicted hydrophilic region within the first alpha-helix, [Ala21,Leu22]IL-3 and [Ala21,Leu22,Ala25]IL-3 showed loss of biological activity and high-affinity binding. Mutants in a second predicted hydrophilic region, [Ala44,Leu45,Ala46]IL-3 and [Ala44,Ala46]IL-3, however, showed similar biological and binding activities to wild-type IL-3. Mutations in a C-terminal hydrophilic region that overlaps the fourth predicted alpha-helix led to either loss or gain of function. IL-3 analogs [Glu104,Asp105]-, [Leu108]-, [Asn108]-, [Thr108]-, and [Ala101,Leu108]IL-3 were less active than wild-type IL-3, whereas [Ala101]IL-3 and [Val116]IL-3 were 2- to 3-fold more potent. Significantly, the double mutant [Ala101,Val116]IL-3 exhibited a 15-fold greater potency than native IL-3. Receptor binding studies showed that [Ala101,Val116]IL-3 exhibited increased binding to the high- and low-affinity receptors of monocytes. These results show the generation of an IL-3 analog with increased biological and binding activities and support a model where the C terminus of IL-3 interacts with the alpha chain of the IL-3 receptor, making this region a useful focus for the development of more potent IL-3 agonists or antagonists.

Amino Acid Sequence↗
PubMed1992

Utilization and evaluation of living-related donors for patients with adult polycystic kidney disease.

Adult onset polycystic kidney disease (ADPKD) causes 10% of all end-stage renal disease in the United States. Use of living-related donors for renal transplants provides significant advantages over cadaver donors. Presymptomatic testing to determine ADPKD status of potential donors by DNA linkage analysis is potentially more accurate than renal ultrasonography for related donors < 30 years old. To determine the utilization of living donor transplants and linkage studies, a survey was mailed to 202 transplant centers in the United Network of Organ Sharing. The 111 respondents reported 5,026 renal transplants done in 1988 of which 390 (7.8%) involved an ADPKD recipient. Only 7% of these 390 transplants utilized a living-related donor compared to the 20% rate reported for all renal transplants. DNA linkage studies were not used by any of the centers performing related donor transplants in 1988 and only 29% reported provision of risk counseling. We conclude that living-related transplants are underutilized for ADPKD recipients due to conservative transplant policies, concern about the inaccuracy of presymptomatic diagnosis, or decreased availability of asymptomatic donors in these families. DNA linkage analysis is also underutilized due to lack of knowledge of its availability and accuracy, concerns about its cost and misconceptions about the accuracy of ultrasonography.(ABSTRACT TRUNCATED AT 250 WORDS)

Cadaver↗
PubMed1992

The NZB mouse as a model for chronic lymphocytic leukemia.

Chronic lymphocytic leukemia (CLL) is the most common leukemia in the Western world and the only leukemia for which a possible genetic component has been described. Analysis of this genetic component has been hindered by the fact that disease onset normally occurs after age 50. We report here the aged NZB mouse as an animal model for CLL. NZB mice have a genetically regulated, age-dependent onset of clonal, aneuploid cells which are IgM+ and Ly1+ (CD5+ B-cells). Peripheral blood smears from old NZB mice show an increase in circulating lymphocytes and "smudged" or ruptured cells, often seen in human CLL. Electron microscopic examination of these cells shows them to be mature lymphocytes. Light microscopy of the spleen shows infiltration of small lymphocytes and is consistent with CLL pathology. These long-lived, CLL-like cells can be serially passaged into recipient animals. This continued passage occasionally results in the development of a large cell lymphoma detectable in the spleen, lymph nodes, and liver. The histology of this lymphoma is quite distinct from that of the CLL-like cells, but the phenotype is that of an aneuploid CD5+, IgM+ cells. This apparently represents a continued transformation of the CLL-like clone similar to the development of Richter's syndrome in human CLL. Therefore, the NZB mouse can be a valuable tool for the determination of the genetic basis of CLL ontogeny and the conversion of CLL into Richter's syndrome.

Age Factors↗
PubMed1992

Seasonal productivity of lizard femoral glands: relationship to social dominance and androgen levels.

Social and hormonal correlates of femoral gland productivity were investigated in groups of adult and juvenile green iguanas (Iguana iguana) over 12 months. Femoral gland productivity, pore size, and the percentage of lipids in the secretions were correlated with plasma testosterone (T) levels in dominant, although not in subordinate, adult males. Secretory activity peaked during the breeding months, at which time dominants produced more secretion than subordinates. Pore size in juvenile males was positively correlated with plasma T levels and frequency of headbob displays in the months corresponding to the adult breeding season. After 18 months of age, individuals that performed visual displays had significantly larger pores than individuals that did not display. These results indicate that femoral gland secretions could function in the ontogeny and maintenance of dominance relationships.

Aggression↗
PubMed1992

Association of poor clinical status and heavy exposure to tobacco smoke in patients with cystic fibrosis who are homozygous for the F508 deletion.

We examined the association between clinical status and exposure to tobacco smoke in 44 patients homozygous for the F508 cystic fibrosis mutation. Heavy exposure to tobacco smoke was significantly associated with lower Shwachman scores, poorer results of pulmonary function tests, and a fivefold increase in the number of pulmonary-related hospitalizations during the previous year.

Adolescent↗
PubMed1992

The molecular biology of human hereditary central diabetes insipidus.

Molecular biology techniques have begun to shed light on the genetic basis of autosomal dominant central DI, but several very basic questions remain to be answered. The disorder was initially presumed to have a developmental, degenerative, or autoimmune basis based on the autopsy findings in the hypothalamus of a limited number of patients. The molecular cloning of the AVP-NP II gene and the clue from the Brattleboro rat that at least this one form of hereditary DI involved an AVP-NP II gene mutation allowed us to focus on this gene in our study of human hereditary DI. Our initial experiments did not show this gene to have a major structural alteration such as a deletion, insertion, or rearrangement, but the approach was not capable of detecting more suitable defects. The linkage studies provided substantial evidence that one particular OT-NP I haplotype was linked to the disease phenotype in each family, and thus, a mutation in the AVP/OT region of chromosome 20 is responsible for this disease. Ito et al. (1991) then identified a single base change in the AVP-NP II gene in affected members of one Japanese family. This change was not detected in unrelated, unaffected persons and thus is a good candidate for the mutation causing the disease in this family. However, there appears to be diversity in the molecular basis of autosomal dominant central DI as affected members of one of our families did not have this particular base change in either AVP-NP II allele and recently another distinct AVP-NP II gene base change has been associated with this disorder. One interesting question still to be addressed is how a mutation in the NP-II coding region of this gene prevents AVP release from the posterior pituitary in the rat or the human disease. Does the disrupted AVP-NP II coding sequence prevent normal processing of the mRNA so that it can not be properly translated into protein? Does the mutated AVP-NP II glycoprotein precursor protein interfere with normal post-translational processing to prevent release of AVP? Is an altered NP II protein not able to protect the AVP from proteolysis within the magnocellular neuron? An even more puzzling question is how a mutation in the gene encoding a hormone is inherited in an autosomal dominant pattern. The Brattleboro rat model follows the a priori expectation of autosomal recessive inheritance: the animal only exhibits a defect in hormone function if both genes encoding the hormone are defective.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1992

The analysis of a multiple-dose, combination-drug clinical trial using response surface methodology.

We consider the situation where a multiple-dose, combination-drug clinical trial is conducted to identify one or more combinations that satisfy regulatory requirements. Generally, these requirements involve a compound hypothesis with multiple comparisons. The min test has been shown to be an optimal alpha-level test for testing a single combination drug. Analysis procedures in a multiple-dose, combination-drug study have typically involved classical ANOVA models or multiple regression models in a response surface methodology (RSM) framework. An inferential procedure based on an ANOVA model uses a screening test to address multiple comparison issues and multiple min tests to explicitly identify combinations satisfying regulatory requirements. An exploratory procedure based on RSM modeling is used to build a segmented linear model and a stairstep linear model to describe dose-response relationships. The two procedures are mutually supportive of one another in providing a broader assurance in the identification of effective combinations.

Analysis of Variance↗
PubMed1992

Cystic fibrosis genotyping by direct PCR analysis of Guthrie blood spots.

In the United States the most common cystic fibrosis (CF) alleles known are F508, G551D, G542X, R553X, and N1303K. These mutations comprise approximately 85% of U.S. CF alleles, and their detection along with analysis of XV-2C and KM-19 restriction fragment length polymorphisms (RFLPs) can enable the determination of CF status. To facilitate studies for determining CF carrier status, we developed methods to detect each of these mutations and RFLPs by direct PCR amplification of dried blood spots collected on newborn screening (Guthrie) cards. Following collection, samples were protected from contamination by individual plastic bags. One-mm2 segments of filter paper were added directly to 100-microliters PCR reactions containing 1/16 mM spermidine. Three initial cycles at 96 degrees C, then 55 degrees C, for 3 min were performed to free DNA and minimize inhibition by other related materials. Next, 1 unit of Taq polymerase was added and a 2-min extension was carried out at 72 degrees C, followed by 33 amplification cycles using denaturing, annealing, and extension temperatures and times optimal for each primer set. Then, 35 microliters of each reaction was run on 8% acrylamide gels directly or 1% agarose gels following digestion; genotypes were inferred by ethidium bromide staining of gels. Guthrie blood spots of 250 CF probands and their parents were screened and the frequencies of all five mutations as well as the XV-2C KM-19 RFLP haplotypes were determined.(ABSTRACT TRUNCATED AT 250 WORDS)

Alleles↗
PubMed1992

Detection of molecular heterogeneity in GH-1 gene deletions by analysis of polymerase chain reaction amplification products.

At least three different sizes of GH-1 gene deletions (approximately 6.7, 7.0 and 7.6 kilobases) have been detected by Southern blot analysis of DNA from individuals with familial isolated GH deficiency type IA (IGHD1A). It is likely that these deletions result from unequal crossing over events between homologous regions that flank the GH-1 gene. Heterogeneity in clinical phenotypes is suggested by reports of good responses to exogenous GH treatment in most IGHD1A subjects with 7.6 kilobase deletions as opposed to poor responses in many subjects with smaller deletions. To determine if characteristic differences in gene deletions could be detected that correlate with response to treatment we analyzed the DNA sequences that normally flank the GH-1 gene. Digestion patterns of the PCR amplification products of these sequences from DNA of IGHD type IA patients with the restriction endonucleases BglI, HaeII, or SmaI showed characteristic differences for each of the three deletion sizes studied. The location and size of all deletions agreed with previous size estimates based on Southern blot analysis. Interestingly, clinical differences observed in the development of high titers of anti-GH antibodies and poor growth responses after GH treatment are unexplained, since discordant outcomes were observed in patients who had deletions of the same size and approximate location.

Base Sequence↗
PubMed1992

Utility of internal markers to improve the accuracy of cystic fibrosis genotype analysis.

DNA diagnostic tests often utilize restriction endonuclease digestion of PCR-amplified portions of genes under analysis. When partial digestion occurs, the resulting patterns may lead to error in diagnosis. To overcome such potential errors in cystic fibrosis testing, we have developed internal markers that can increase the precision and reliability of genotype assignments.

Cystic Fibrosis↗
PubMed1992

Industrial workers on a rotating shift pattern: adaptation and injury status.

Over 11 million Americans work some type of shift pattern. Numerous health and safety issues result when workers follow a rotating shift schedule. Over 5 million work-related injuries occur annually in the United States at a cost of almost $48 billion. Disrupted circadian rhythms and fatigue from rotating shifts have been implicated as a cause of traumatic injuries. This study revealed that factors related to circadian type, effects of the work environment, and coping styles explained over 51% of the variance in adaptation scores for this group of rotating shiftworkers. Adaptation levels were not significantly different for the injured and non-injured groups of shiftworkers. Findings of this research suggest that education on the effects of circadian rhythm disruption and more effective ways of coping may be justified. Also, additional research related to adaptation and injuries is needed.

Accidents, Occupational↗
PubMed1992

The cystic fibrosis gene and relationships to clinical status.

Cystic fibrosis (CF) is a disease characterized by significant variability in both presentation and clinical course. The genetic and environmental factors responsible for the phenotypic expression of CF are most likely legion, and their relationship to the disease complex. Therefore, it was not until the isolation and characterization of the CF gene and the ability to genotype individual patients that further elucidation of the genotype-phenotype relationship in CF was possible. Currently, the pancreatic status of CF patients appears to be primarily determined by genetic factors and patients homozygous for the most common mutation, delta F508 are, as a rule, pancreatic insufficient. Other specific alleles that confer pancreatic sufficiency have been identified. Patients having these alternative alleles remain pancreatic sufficient, are diagnosed later, have lower sweat chloride values, milder respiratory disease, and a better prognosis than patients with alleles associated with pancreatic insufficiency. Other clinical manifestations, including meconium ileus and the presence of liver disease, appear to be associated with pancreatic insufficiency. The variability in the pulmonary course for homozygous delta F508 patients suggests that genetic heterogeneity at other loci or environmental factors are important. Therefore, the CF genotype does not precisely predict pulmonary status.

Chromosomes, Human, Pair 7↗
PubMed1991

Presymptomatic testing for adult onset polycystic kidney disease in at-risk kidney transplant donors.

Autosomal dominant adult-onset polycystic kidney disease (ADPKD) is estimated to have an incidence of 1/1,000 and accounts for approximately 10% of all end-stage renal disease in the United States. While relatives are attractive as renal donors due to their availability and the improved transplant success associated with living-related donors, they may coincidentally be at risk for ADPKD. Accurate presymptomatic testing for at-risk potential donors is critical for both the donor and the recipient. We report here 2 families in which presymptomatic testing for ADPKD was accomplished by DNA linkage analysis on several potential renal donors prior to transplant. This resulted in the protection of both donors and recipients by preventing the transplantation of a kidney affected by ADPKD. Thorough counseling prior to DNA analysis (including discussion of accuracy and possible testing outcomes of presymptomatic diagnosis of ADPKD, diagnosis of noncarrier status, false paternity, and non-informative study) was essential to provide informed consent and preserve confidentiality within the family. Confidentiality for potential donors found presymptomatically to be affected (with a 94% or greater probability) was especially difficult to maintain.

Female↗
PubMed1991

Molecular characterization of severe hemophilia A suggests that about half the mutations are not within the coding regions and splice junctions of the factor VIII gene.

Hemophilia A is an X chromosome-linked disorder resulting from deficiency of factor VIII, an important protein in blood coagulation. A large number of disease-producing mutations have been reported in the factor VIII gene. However, a comprehensive analysis of the mutations has been difficult because of the large gene size, its many scattered exons, and the high frequency of de novo mutations. Recently, we have shown that nearly all mutations resulting in mild-to-moderate hemophilia A can be detected by PCR and denaturing gradient gel electrophoresis (DGGE). In this study, we attempted to discover the mutations causing severe hemophilia A by analyzing 47 unselected patients, 30 of whom had severe hemophilia and 17 of whom had mild-to-moderate disease. Using DGGE as a screening method, we analyzed 99% of the coding region, 94% of the splice junctions, the promoter region, and the polyadenylylation site of the gene. We found the mutation in 16 of 17 (94%) patients with mild-to-moderate disease but in only 16 of 30 (53%) patients with severe hemophilia A. Since DGGE after computer analysis appears to detect all mutations in a given fragment, the lower-than-expected yield of mutations in patients with severe disease is likely not due to failure of the detection method; it is probably due to the presence of mutations in DNA sequences outside the regions studied. Such sequences may include locus-controlling regions, other sequences within introns or outside the gene that are important for its expression, or another gene involved in factor VIII expression that is very closely linked to the factor VIII gene.

Amino Acid Sequence↗