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Biomedical subjects

R L Kirk

Publications and source records attributed to R L Kirk.

At least 19 recordsLinked to original sources
PubMed2002

Observations of comet 19P/Borrelly by the miniature integrated camera and spectrometer aboard Deep Space 1.

The nucleus of the Jupiter-family comet 19P/Borrelly was closely observed by the Miniature Integrated Camera and Spectrometer aboard the Deep Space 1 spacecraft on 22 September 2001. The 8-kilometer-long body is highly variegated on a scale of 200 meters, exhibiting large albedo variations (0.01 to 0.03) and complex geologic relationships. Short-wavelength infrared spectra (1.3 to 2.6 micrometers) show a slope toward the red and a hot, dry surface (</=345 kelvin, with no trace of water ice or hydrated minerals), consistent with approximately 10% or less of the surface actively sublimating. Borrelly's coma exhibits two types of dust features: fans and highly collimated jets. At encounter, the near-nucleus coma was dominated by a prominent dust jet that resolved into at least three smaller jets emanating from a broad basin in the middle of the nucleus. Because the major dust jet remained fixed in orientation, it is evidently aligned near the rotation axis of the nucleus.

Carbon↗
PubMed1999

Genetic studies on Gadaba: a tribal population of Andhra Pradesh, India.

Blood samples were collected from Gadaba, a tribal population of Andhra Pradesh, South India, in order to examine the distribution of blood groups, red cell enzymes and the gammaglobulin polymorphism. Out of 20 genetic markers studied seven protein loci exhibited monomorphism. Surprisingly a case of a rare homozygous variant and twenty-one heterozygous variants at the phosphogluconate dehydrogenase locus (6-PGD), six variants at the phosphohexose isomerase locus (PHI) and a single case of phosphoglucomutase locus 1 (PGM 1) variant were observed. Further, the tribal populations of South India reveal higher frequencies of rare variants than the caste populations. However, the presence of rare variants that are phenotypically neutral may be plausibly due to their high selective value.

Adolescent↗
PubMed1997

Results from the Mars Pathfinder camera.

Images of the martian surface returned by the Imager for Mars Pathfinder (IMP) show a complex surface of ridges and troughs covered by rocks that have been transported and modified by fluvial, aeolian, and impact processes. Analysis of the spectral signatures in the scene (at 440- to 1000-nanometer wavelength) reveal three types of rock and four classes of soil. Upward-looking IMP images of the predawn sky show thin, bluish clouds that probably represent water ice forming on local atmospheric haze (opacity approximately 0.5). Haze particles are about 1 micrometer in radius and the water vapor column abundance is about 10 precipitable micrometers.

Atmosphere↗
PubMed1995

Red cell 6-phosphogluconate dehydrogenase polymorphism in the Gadaba of Andhra Pradesh (India). Report of new variant phenotypes.

Blood samples from 1000 unrelated, adult individuals of the Gadaba tribal population were screened for 6-phosphogluconate dehydrogenase. We report the occurrence of a new fast moving variant, which is caused by the allele PGD* Gadaba. This allele is reported for the first time among the tribal populations of Andhra Pradesh. Its frequency comes to 0.0115, and it was observed in heterozygous (2.10%) and homozygous (0.10%) conditions.

Adult↗
PubMed1992

Genetic affinities of oceanic populations based on RFLP and haplotype analysis of genetic loci on three chromosomes.

Restriction fragment length polymorphisms at the renin and factor 13B loci located at chromosome 1q32-1q42 were studied in 14 ethnic groups in the west Pacific region. The allele frequencies were combined with previously described beta-globin and albumin-vitamin D binding protein haplotype frequencies and used to assess genetic affinities among eight major ethnic-geographic groups in this region. These population groups divide into two clusters with Australian Aborigines, Island Melanesians, and Highland Melanesians forming one cluster and east Asians, Southeast Asians, Micronesians, and Polynesians forming the other. The results indicate that Micronesians and Polynesians are derived from populations in Southeast Asia and that they originated independently of the Melanesian populations.

Beta-Globulins↗
PubMed1990

Albumin--vitamin D-binding protein haplotypes in Asian-Pacific populations.

We have determined the various haplotypic combinations between alleles as well as restriction fragment length polymorphisms of two linked genetic markers, albumin and vitamin D-binding protein or group-specific component, in a number of Asian-Pacific populations. Using the partial maximum likelihood method, we constructed a phylogenetic network from the haplotype frequencies to assess relationships among the populations sampled. No systematic linkage disequilibrium was detected between most of the combinations, suggesting a lack of operation of any selection pressure at the two loci. The phylogenetic analysis confirmed the known interrelationships among various populations in the Asian-Pacific region. The Australian aborigines clustered closely with the non-Austronesian-speaking highlanders from Papua New Guinea, as expected. Similarly, the Austronesian-speaking Polynesians, Micronesians, and the Southeast Asians branched off together as a separate group. The position of the Austronesian-speaking Tolais from New Britain with respect to other populations from the Southwest Pacific was anomalous. The Tolais revealed a strong affinity with the Australian aborigines, which is inexplicable. The populations from China formed a tight cluster with other populations from the Asian-Pacific region. Genetic interrelationships of these populations with the white Australians were remote, which is in accordance with the known affinities of various human racial groups.

Alleles↗
PubMed1990

Evolution of beta-globin haplotypes in human populations.

The beta-globin haplotypes of 852 chromosomes from 12 populations in the Asia-Pacific region are described. These data are combined with those from other populations in an investigation of the affinities of regional human populations. Both partial maximum-likelihood and distance Wagner methods indicate that Africans are the most divergent group, with the remaining populations branching in the following order: Australian Aborigines, Highland Melanesians, Lowland Melanesians, Indonesians and Micronesians, Polynesians, east Asians, Indians, and Europeans. This pattern of relationship is consistent with that indicated by other data. Analysis of the evolution and distribution of haplotype occurrence provides some limited support for an origin of modern humans in Africa. Otherwise, however, it was not useful in further elucidating the evolutionary history of human populations.

Animals↗
PubMed1987

HLA-DR and -DQ DNA genotyping in insulin-dependent diabetes patients in South India.

Restriction fragment length polymorphisms (RFLPs) of the HLA-DR beta, -DQ alpha, -DQ beta, and -DX alpha genes have been examined in South Indian diabetic patients and controls. The DR. DQ linkage arrangements in South Indians were shown to be different for DR2, DR4, and DRw6 from those commonly seen in Europeans, so that localization of the primary disease-promoting gene in IDDM could be attempted. This study clearly implicates at least one DQ beta allele in the pathogenesis of IDDM.

DNA Probes, HLA↗
PubMed1987

Red cell enzyme and serum protein gene markers in Fijians.

A total of 332 persons from three localities in the Fiji Islands have been tested for genetic variation in 24 red cell enzyme systems and 4 serum protein systems. Polymorphic variation was present at 7 red cell enzyme loci and 1 serum protein locus. The remaining systems were invariant except for a single individual with a slow variant at the GOT1 locus and another individual with a D variant at the TF locus. The series from Nandi differed significantly from the Lau Islands for gene frequencies in GPT, ACP and ESD, Koro Island differed from the other localities at the PGD locus and from Nandi for ESD. Genetic distance analysis reveals that Lau Islands cluster with Western Samoa, Koro Island with New Caledonia (Vanuatu), with Nandi being separate.

Blood Proteins↗
PubMed1986

Genetic variants of 6-phosphogluconate dehydrogenase in the Indonesian populations.

Blood samples from 2,091 individuals representing 14 Indonesian populations (11 Austronesian and 3 non-Austronesian speakers) have been tested electrophoretically for 6-phosphogluconate dehydrogenase (6-PGD). Two common alleles, PGDA and PGDC are found in all populations studied, and the phenotype distribution agrees well with the Hardy-Weinberg equilibrium. The PGDC gene frequency varies from as low as 3.5% in the Galelarese to 29% in the Asmat. In general, the PGDC allele seems to decrease in frequency towards the west. A low frequency of PGDC in the Galelarese, a non-Austronesian-speaking population, is thought to be the result of admixture of Austronesian genes, which has not led to language change. In addition to the common alleles, a new variant, PGD A-Lombok, is also described.

Alleles↗
PubMed1985

HLA, complement C2, C4, properdin factor B and glyoxalase types in South Indian diabetics.

A series of diabetic patients from 3 centres in South India have been tested for HLA A, HLA B, BF, C2, C4A, C4B and GLO types. For insulin-dependent diabetes mellitus (IDDM) patients there was a significant increase in HLA B8, of BF F and decrease of C4 A6. No significant variation in HLA, BF, C2 or GLO frequencies was found in non-insulin-dependent diabetes mellitus (NIDDM) patients, but there was a significant decrease in C4B 1 and an increase in C4B 2. The HLA and BF association in South Indian IDDM patients is very different from that reported previously in North India.

Adolescent↗
PubMed1985

Genetic and environmental influence in the epidemiology of noninsulin-dependent diabetes mellitus: a global perspective.

Refinement of the classification of diabetes mellitus to include two major categories, insulin dependent (IDDM) and noninsulin-dependent (NIDDM) and the recent attention paid to the standardization of epidemiological techniques have led to much new information on the epidemiology of the disease. Support for the notion of genetic influence in the development of NIDDM has come from twin studies, but the search for specific genetic markers for NIDDM has been largely unproductive to date. There is increasing scepticism as to the utility of the chlorpropamide-alcohol flush as a genetic marker for NIDDM. The large disparity in the frequency of NIDDM between populations provides indirect support for the genetic hypothesis, as do recent studies of the association between NIDDM and ancestral genetic admixture. Obesity has long been considered a causal factor in the aetiology of NIDDM, though the strength and consistency of this relationship is now being questioned. The strength of the association between obesity and NIDDM has been shown to vary depending on the presence or absence of a family history of the disease. There is further preliminary evidence to suggest that association between obesity and NIDDM may vary in strength between populations, and between the sexes. Little evidence has so far emerged for a role of quantitative or qualitative aspects of diet in the aetiology of NIDDM. This may be due, in part, to the imprecision of current techniques for dietary estimation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Population genetics of the vitamin D binding protein (GC) subtypes in the Asian-Pacific area: description of new alleles at the GC locus.

Isoelectric focussing (IEF) in thin layer polyacrylamide gels pH range 4-6.5 has been used to analyse the GC phenotypes of 4233 individuals from 28 different population groups in the Asian, Pacific, and Australian area. Because this technique reveals subtypes of the common GC*1 allele, there is almost a two-fold increase in the mean heterozygosity at the GC locus using IEF compared with conventional electrophoresis. The highest frequency (above 50%) of the GC*1S allele was encountered in Indian populations, reflecting genetic affinities with Europeans. By comparison, east and south east Asians are unique offing maximum values of the GC*1F allele (50%). With the exception of a few Pacific populations which show similar frequencies to east Asians, all other groups in the Pacific area, including Australia, have values of GC*1F similar to GC*1S ranging from 27% to 40%. The GC*2 frequency in most populations varies from 20% to 30%. However, some Polynesian groups have values up to 40% and Australian Aborigines less than 10%. Among other alleles, GC*1A1 is found to be widely distributed among Australian Aborigines and Melanesians and occurs sporadically in Polynesians, Micronesians, and in the Lesser Sunda Islands. Four new alleles, GC*1C24, GC*1C35 Aborigine, GC*1A21, and GC*1A22 are described. The gene frequency data at the GC locus has been used to calculate Nei genetic distances between the populations studied.

Alleles↗
PubMed1983

Search for a red cell enzyme or serum protein marker in amyotrophic lateral sclerosis and parkinsonism-dementia of Guam.

Frequency distributions were determined for 24 red cell enzyme and four serum protein systems, in an attempt to identify a genetic marker associated with either amyotrophic lateral sclerosis (ALS) or parkinsonism-dementia (PD), two progressive and fatal neurological disorders of unknown cause found with unusually high incidence among the Chamorros of Guam and the Northern Mariana Islands. No striking associations were identified between either disorder and any of the gene markers tested. Thus, no genetic cause is known for either disease; local environmental factors are most likely involved in pathogenesis.

Amyotrophic Lateral Sclerosis↗
PubMed1983

A population genetic study of the Banks and Torres Islands (Vanuatu) and of the Santa Cruz Islands and Polynesian Outliers (Solomon Islands).

As part of a multidisciplinary survey of populations in the Banks and Torres Islands of Vanuatu and the Southern and Central Districts of the Solomon Islands, nearly 2,400 persons have been tested for ABO blood groups and a number of serum protein and red cell enzyme genetic marker systems. For the ABO system, the populations are characterized in general by high gene O and low gene B frequencies except in two of the Polynesian Outlier Islands, Rennell and Bellona, which have high frequencies of B. Among the serum proteins, several alleles have distributions indicating significant movement of people between islands. These include Albumin New Guinea and the transferrin alleles TfD1, and TfBLae, and TfB2. Similar specific alleles for red cell enzymes also show distributions reflecting interisland population movement as well as contact with persons from outside the southern Pacific region. Examples are ACPR1 in the acid phosphatase system, PGM31 and PGM71, PGM92, and PGM102, PGK4 and also HbJTongariki. The data available for 11 polymorphic systems were used to generate genetic distances. Of the four Polynesian Outlier Islands, Anuta is most remote genetically, with Rennell and Bellona also relatively isolated. The fourth Polynesian Outlier, Tikopia, occupies a position genetically close to the Melanesian populations of the Banks and Torres Islands and the southern Solomons. The history of early European contact and voyaging in the Pacific, as well as archaeological and linguistic evidence and local legends, indicate that significant movements of people occurred between islands and provided opportunities for genes to be introduced from Europeans, Africans, and Asians. The genetic marker studies give evidence for genes from all these sources, though at a low level. Despite this admixture, the Polynesian Outlier and Melanesian populations have preserved their own distinctive genetic patterns.

ABO Blood-Group System↗
PubMed1983

The polymorphism of the vitamin D-binding protein (Gc); isoelectric focusing in 3 M urea as additional method for identification of genetic variants.

Since the last report numerous new DBP (Gc) variants have been observed; at present a total of 84 different mutants can be distinguished. Several of them have similar electrophoretic mobilities and/or isoelectric points of conventional isoelectric focusing (IEF). IEF in polyacrylamide gels in the presence of 3 M urea is a convenient and efficient method for the detection of hidden variation.

Carrier Proteins↗