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Biomedical subjects

J D Reid

Publications and source records attributed to J D Reid.

At least 37 records · Page 2Linked to original sources
PubMed1996

Cloning the cDNA of human PWP2, which encodes a protein with WD repeats and maps to 21q22.3.

We have used exon trapping to contribute to the development of the transcription map of chromosome 21q22.3 and to clone the genes responsible for disorders that map in the 21q22.3 region. Polypeptides deduced from three trapped sequences that map near PFKL showed homology to the yeast PWP2 gene. The full-length coding region of a human homologue of this yeast gene was subsequently cloned from human infant brain and fetal kidney cDNA libraries. The 919-codon open reading frame of human PWP2 belongs to the family of genes that contain tryptophan-aspartate (WD) repeats; other than its yeast counterpart, PWP2 is most closely homologous to the beta subunits of the trimeric G-protein family and may putatively be involved in signal transduction. Northern blot analysis revealed that the PWP2 gene is expressed in all fetal and adult human tissues examined (3.4 kb mRNA species). This single-copy gene maps approximately 200 kb proximal to PFKL in chromosome 21q22.3 between markers EHOC-1 and D21S25.

Adult↗
PubMed1996

The SpTRK gene encodes a potassium-specific transport protein TKHp in Schizosaccharomyces pombe.

Complementary DNAs involved in potassium transport in Schizosaccharomyces pombe were selected by complementation of defective K+ uptake in a trk1 trk2 mutant of Saccharomyces cerevisiae. Here we describe the SpTRK gene that encodes a protein of 833 amino acids. The predicted structure contains 12 putative membrane-spanning domains and resembles various high- and low-affinity systems for K+ transport in yeasts and plants. TKHp, the product of SpTRK exhibits high homology to TRK1 and TRK2 of Saccharomyces cerevisiae as well as to HKT1 of Triticum aestivum, but is not related to HAK1 of another ascomycete, Schwanniomyces occidentalis, suggesting that different routes for potassium uptake evolved independently. This protein is a potassium-specific transporter since functional analysis of the SpTRK complemented mutant strain of Sacch. cerevisiae revealed potassium transport affinities and uptake characteristics similar to those obtained in wild-type Sch. pombe. Patch-clamp analysis in the whole-cell mode confirmed the TKHp-mediated inward current in the complemented strain. The inward current increased by acidification of the extracellular medium thereby suggesting a mechanism of K+H+ cotransport. The inward current is not detectable when external K+ is substituted by Na+, documenting a distinct cation specificity of the protein.

Amino Acid Sequence↗
PubMed1996

Prosthetic-vein composite graft with remote popliteal arteriovenous fistula.

BACKGROUND: Inadequate autogenous vein is often the limiting factor in femoral-distal reconstruction. Sequential grafts, distal arteriovenous fistulae (AVF), and autogenous cuffs have been recommended in this setting. This paper describes a new method of composite reconstruction, enhanced with a popliteal AVF. PATIENTS AND METHODS: Data was collected prospectively on 13 patients (14 limbs) who presented with severe ischemia (rest pain or ulcer 6, gangrene 8). The average age was 75 years. Eleven of the reconstructions were to tibial outflow tracts. The novelty of the technique is in the construction of a controlled AVF between the upper end of an autogenous vein graft and the popliteal vein. An uncomplicated autogenous anastomosis is created distally. The synthetic graft is placed between the common femoral artery and the vein graft distal to the AVF. The flow is balanced between the fistula and the outflow tract by narrowing the fistula while monitoring the pressure in the graft system. RESULTS: Patency was assessed by color duplex scan. Two grafts occluded (at 5 and 7 months) and 1 was revised at 12 months. Mean peak systolic velocity in the synthetic portion was 130 cm/s. Limb edema has not been a problem. There were 2 perioperative cardiac deaths. Mean follow up is 15 months (range 6 to 36). CONCLUSION: The addition of a controlled AVF below the synthetic portion of a composite graft appears promising when vein is in limited supply.

Aged↗
PubMed1996

A measurement model of cortisol reactivity of healthy older adults.

Research on the physiological adaptation process has found that stress is associated with the rate of cortisol secretion, the main hormone that reflects stress. However, considerable variation among subjects has been reported. Using a sample of older adults (N=46), we tested the hypothesis that cortisol reactivity is composed of (1) a situation-related component representing hypothalamic influence on cortisol secretion observed on three different occasions, and (2) a stable component representing a general trait responsible for cortisol responses observed from occasion to occasion. LISREL VIII was used to test this hypothesis. Results indicated that a homogeneous reliability model was not supported by the data. A congeneric measurement model represented a better fit to the data. Results suggest that subjects have consistent patterns of response during separate experimental occasions. However, results do not suggest a consistent pattern of response over time. The main implication of these results is that salivary cortisol measures are sensitive to experimental stress situations. As such, this noninvasive method may be useful in examining adaptive responses to stress.

Adaptation, Psychological↗
PubMed1996

The S. cerevisiae outwardly-rectifying potassium channel (DUK1) identifies a new family of channels with duplicated pore domains.

Potassium channel subunits have six or two transmembrane segments in addition to a conserved pore-forming (P) domain; four subunits come together to form a channel. A gene was identified in S. cerevisiae (J0911) encoding a protein with eight probable membrane-spanning segments and two such P regions. This protein (Duk1p) is a potassium channel because Xenopus oocytes injected with the corresponding RNA express potassium currents activated by depolarization that are not seen in control oocytes. Similar potassium currents were recorded from wildtype S. cerevisiae spheroplasts, but not from those in which the DUK1 locus had been disrupted. Cells carrying the duk1 delta 1::HIS disruption in addition to a chimeric gene comprising DUK1 behind the GAL1 promoter showed outward currents when grown in galactose, but not when grown in glucose. Additional sequences with the duplicate pore motif were found in C. elegans, suggesting that these proteins represent a novel structural family of potassium channel proteins.

Amino Acid Sequence↗
PubMed1995

The guanine-nucleotide-binding protein subunit G alpha i2 is involved in calcium activation of phospholipase A2. Effects of the dominant negative G alpha i2 mutant, [G203T]G alpha i2, on activation of phospholipase A2 in Chinese hamster ovary cells.

The mechanisms of activation of cytoplasmic phospholipase A2 (cPLA2) are complex and incompletely defined. In Chinese hamster ovary (CHO) cells, receptor stimulation of cPLA2 is due to the interaction of pathways involving the alpha subunits of at least two guanine-nucleotide-binding (G) proteins, G alpha i2 and G alpha q. Activation of cPLA2 is inhibited by pertussis toxin and G alpha i2 mutants. In addition, activation of phospholipase C via G alpha q results in increased intracellular calcium ([Ca2+]i) and activation of protein kinase C, both of which interact with and activate cPLA2. The present study was undertaken to analyze the mechanism of interaction of G alpha i2 with the phospholipase-C-stimulated pathway in the activation of cPLA2. We addressed this question using a dominant negative G alpha i2 mutant, [G203T]G alpha i2, in which Gly203 is mutated to Thr. [G203T]G alpha i2 inhibits ATP receptor activation of cPLA2. The effect of [G203T]G alpha i2 was specific to G alpha i2-activated pathways, as shown by its lack of effect on other purinergic receptor stimulated pathways: ATP stimulation of [Ca2+]i or mitogen-activated protein kinase phosphorylation is unaltered by [G203T]G alpha i2. We addressed the possibility that the activation of cPLA2 by Ca2+ and/or protein kinase C is dependent on G alpha i2. Activation of cPLA2 by the Ca2+ ionophore, ionomycin, was inhibited by 61 +/- 9% (n = 5) in [G203T]G alpha i2-expressing cells; however the ionomycin-induced [Ca2+]i rise was unaffected by [G203T]G alpha i2. Thus, [G203T]G alpha i2. specifically inhibits Ca2+ activation of cPLA2. In contrast, activation of cPLA2 via protein kinase C by phorbol 12-myristate 13-acetate was unaffected by [G203T]G alpha i2. Our results demonstrate that Ca2+ but not phorbol ester activation of cPLA2 in CHO cells is G alpha i2-dependent. The possibility is discussed that G alpha i2 is downstream of Ca2+ but upstream of protein kinase C activation of cPLA2.

Animals↗
PubMed1994

Superficial femoral vein: a useful autogenous harvest site.

PURPOSE: The purpose of this study was to present the use of superficial femoral vein (SFV) as an arterial bypass graft when ipsilateral saphenous vein is inadequate. METHODS: Data collected prospectively were reviewed on 24 patients (25 limbs) who had an arterial bypass with SFV performed by the authors between January 1, 1988, and December 31, 1991. Many anatomic sites are represented. The indication for operation was gangrene in six patients, severe rest pain or ulceration in 11, mild to moderate rest pain in six, and graft infection in two. There had been 42 previous reconstructions in these 25 limbs. RESULTS: There has been surprisingly little long-term disability from removal of the SFV. Immediately after surgery four limbs developed acute venous congestion that resolved quickly. Twenty percent of the patients with patent grafts have continued to wear a pressure gradient stocking for swelling 1 year after surgery, one patient requires additional pressure to control induration. All grafts were patent at 30 days. During a mean follow-up of 2 years, three grafts have required revision, and three have occluded. Stenosis did not develop at valve sites or in the body of the SFV portion of any of these grafts. There were two deaths from heart-related causes in the first 30 days after operation. Life-table analysis for the whole group shows a primary patency rate of 66% (SE 10.3%) and an assisted patency rate of 80% (SE 8.7%) at 2 years. CONCLUSIONS: SFV harvest is well tolerated, even in the absence of ipsilateral saphenous vein. The magnitude of the operation is greater than saphenous vein harvest but yields a thick-walled vein of excellent diameter with many applications as an autogenous conduit, particularly where a large-diameter graft is indicated.

Aged↗
PubMed1994

Exposure of the anterior tibial artery by medial popliteal extension.

This report describes exploration of the proximal anterior tibial artery by extension of the standard below-knee approach to the popliteal artery. The anterior tibial artery is "poplitealized," giving excellent access to perform an anastomosis. The proximal medial approach depends on precise arteriography and is particularly suited to the in situ saphenous vein bypass and redo surgery. Advantages over previously described exposures include a shorter graft, ease of graft alignment, protection of the peroneal nerve, and the absence of a lateral counterincision. This exposure has been used on 12 of 14 anterior tibial grafts during the past 2 years.

Anastomosis, Surgical↗
PubMed1993

The molecular cloning of the squid (Loligo forbesi) visual Gq-alpha subunit and its expression in Saccharomyces cerevisiae.

The sequence of the alpha-subunit of the major G-protein from the squid (Loligo forbesi) retina was predicted from its cDNA to be a member of the Gq subclass. The abundance of the squid Gq-alpha in the squid photoreceptor membranes suggests that the protein functions in phototransduction; the sequence of this G-protein is consistent with it mediating the light-dependent activation of a phospholipase C. The squid G-alpha was expressed in the yeast Saccharomyces cerevisiae, where it was unable to replace the function of GPA1, the yeast G-alpha homologue that regulates the mating response, suggesting that Gq-alpha was unable to interact with the endogenous G-beta gamma (STE4-STE18).

Amino Acid Sequence↗
PubMed1993

Medial calcification (whitlockite) in the aorta.

Calcified deposits in the tunica media of the human aorta have been studied in 128 cases by light microscopy and by electron microscopy and analytical methods in selected samples. Although dissolved and not visible in routine histology with alum hematoxylin stains, such calcification can be clearly seen after methylene blue staining in the form of unstained refractile particles of 1-2 microns size. These are found between the elastic laminae chiefly in the inner two-thirds of the media and appear at about age 20. By X-ray diffraction supported by energy dispersive X-ray analysis, they have been identified as whitlockite (Ca,Mg)3(PO4)2. Statistical analysis shows a significant increase in numbers with age and significant differences in severity related to county of origin but no differences between sexes or races and no correlation with deaths related to cardiovascular diseases. Among various substructures of the aortic wall, no unique crystal precursor was identified. Possible etiologic factors and clinicopathologic significance are considered.

Adolescent↗
PubMed1993

Serologic reactivity against Mycobacterium paratuberculosis antigens in patients with sarcoidosis.

Although sarcoidosis has clinical and histopathologic similarities to some forms of tuberculosis and other mycobacterial infections, attempts to establish a mycobacterial etiology have not been successful. Using cytoplasmic antigens derived from a wild strain of Mycobacterium paratuberculosis in an enzyme-linked immunosorbent assay, patients with sarcoidosis were found to have immunoglobulin levels significantly higher than those found in a control population in the IgG, but not in IgA or IgM antibody classes. Results were comparable to those reported from patients with Crohn's disease, where M. paratuberculosis has been intensively studied as a possible etiologic agent. To elucidate these relationships, examination of DNA from sarcoid tissues for possible homology with DNA from M. paratuberculosis and closely related organisms, as well as cultural attempts with techniques and media appropriate for M. paratuberculosis may be warranted.

Adult↗
PubMed1993

Thrombolysis for occluded vein bypass grafts through surgical access.

PURPOSE: This report describes surgical access to occluded vein grafts for thrombolysis by direct cutdown where indirect angiographic techniques have failed. METHOD: A sheath is introduced directly into the proximal vein graft. Distal thrombus is lysed following standard protocol. The residual thrombus at the origin of the graft is removed surgically, and the area is closed with a patch angioplasty. RESULTS: Distal thrombus was completely lysed in two vein grafts without bleeding complications. CONCLUSION: The thrombus "cork" that forms at the upper end of an occluded vein graft may deflect the angiographer's guide wire, but the distal thrombus usually remains soft and amenable to lysis. Angiographic access should not be a limiting factor in thrombolysis of an occluded vein graft.

Graft Occlusion, Vascular↗
PubMed1992

Sizing of crimped Dacron grafts.

The aim of this study was to correlate the stated size of Dacron grafts (Microvel) with their actual internal diameter and to compare this with measurements by ultrasound in the early postoperative period. Grafts of stated diameters of 7, 8, 9, and 10 mm were studied. Grafts were measured by graded probes and by measuring the width of the longitudinally opened graft and calculating the diameter. Each graft accepted a probe 1 mm larger than its stated size very easily and 2 mm greater when stretched. By open measurement, the grafts were 1.3 to 1.8 mm greater than their stated diameter without stretching. Twenty grafts were studied by duplex ultrasound for diameter and peak systolic velocity within 3 months of implantation. The grafts were 12% larger than their stated graft size. Some of the larger grafts showed low velocity and wall thrombus. We conclude that Microvel grafts are larger than their stated diameter. The same size discrepancy was seen in in vitro measurements of Vascutek (Dacron) grafts but not in polytetrafluoroethylene (Gortex) grafts. Since flow velocity is related to the diameter of the graft, this information should be useful when choosing the diameter of a prosthetic vascular graft.

Blood Vessel Prosthesis↗
PubMed1992

The relationship of serum and salivary cortisol in a sample of healthy elderly.

The purpose of this study was to assess the validity of salivary cortisol as an index of adrenocortical activity in older adults. Serum and salivary cortisol samples were collected in a sample of 36 healthy older adults (mean age = 66.64). The relationship of serum and salivary cortisol levels was assessed using correlation and regression analyses. In addition, the stability of serum and salivary levels over repeated samplings was assessed. The findings indicate that salivary measures of cortisol covary with serum levels, and both measures remain stable over repeated samplings. The utility of salivary cortisol as a marker of physiological reactivity is discussed. Future research is recommended to explore the emotional correlates of physiological reactivity in older adults.

Aged↗
PubMed1992

Atherectomy. Early use of three different methods.

The authors report their initial experience in 52 patients with three different techniques of peripheral artery atherectomy--the Tracwright (Kensey), used in 19 patients, the Simpson AtheroCath, used in 19 patients and the transluminal extraction catheter, used in 14 patients. The indications for atherectomy were claudication in 42 (80%) and limb-threatening ischemia in 10 (19%). There were no deaths. Complications included three arterial perforations, one thrombosis and one groin hematoma requiring operative evacuation. There were no distal embolizations. Atherectomy was initially unsuccessful in 15 (29%) patients. For the successfully completed procedures, the 1-year primary patency rates were as follows: Tracwright (Kensey) catheter 56%, Simpson catheter (63%) and transluminal extraction catheter (0%). Use of subsequent nonoperative procedures on recurrent stenoses produced secondary patency rates of 77% for the Tracwright (Kensey) technique, 80% for the Simpson catheter technique and 78% for the transluminal extraction catheter technique. The authors conclude that their early results justify further evaluation of these three techniques. Use of the transluminal extraction catheter is associated with higher rates of occlusion and restenosis.

Aged↗
PubMed1991

Calcium oxalate in mammalian thyroids: a re-evaluation.

Although calcium oxalate crystals in the thyroid have been thought to occur only in human glands, this compound may be found in thyroid glands of a wide variety of mammalian species. Mechanisms underlying the formation of these deposits and their biological significance remain unclear but various possibilities are discussed.

Animals↗