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Biomedical subjects

S Wynchank

Publications and source records attributed to S Wynchank.

At least 19 recordsLinked to original sources
PubMed1998

Lead absorption and renal dysfunction in a South African battery factory.

OBJECTIVES: To test the association between inorganic lead (Pb) exposure, blood pressure, and renal function in South African battery factory workers, with both conventional and newer measures of renal function and integrity. METHODS: Renal function measures included serum creatinine, urea, and urate (n = 382). Urinary markers (n = 199) included urinary N-acetyl-beta-D-glucosaminidase (NAG), retinol binding protein, intestinal alkaline phosphatase, tissue non-specific alkaline phosphatase, Tamm-Horsfall glycoprotein, epidermal growth factor, and microalbuminuria. RESULTS: Mean current blood Pb was 53.5 micrograms/dl (range 23 to 110), median zinc protoporphyrin 10.9 micrograms/g haemoglobin (range 1.9 to 104), and mean exposure duration 11.6 years (range 0.5 to 44.5). Mean historical blood Pb, available on 246 workers, was 57.3 micrograms/dl (range 14 to 96.3). After adjustment for age, weight and height, positive exposure response relations were found between current blood Pb, historical blood Pb, zinc protoporphyrin (ZPP), and serum creatinine and urate. Blood pressure was not associated with Pb exposure. Among the urinary markers, only NAG showed a positive association with current and historical blood Pb. CONCLUSION: An exposure-response relation between Pb and renal dysfunction across the range from < 40 to > 70 micrograms/dl blood Pb was found in this workforce, with conventional measures of short and long term Pb exposure and of renal function. This could not be explained by an effect on blood pressure, which was not associated with Pb exposure. The findings probably reflect a higher cumulative renal burden of Pb absorption in this workforce in comparison with those in recent negative studies. The results also confirm the need for strategies to reduce Pb exposure among industrial workers in South Africa.

Acetylglucosaminidase↗
PubMed1997

Novel proprioceptive action in stepping down.

A hypothesis is offered which extends the concept of proprioception to use information necessarily obtained during the first part of a complex motion (stepping down) to facilitate the second part. It is suggested that, when the leading foot of a normal person stepping down arrives at its destination, relevant proprioceptive information is used by the following foot in its descent, to render its movement more efficient. Analogy to another effort-minimizing proprioceptive mechanism and a possible mechanical manifestation of the hypothesis are given.

Biomechanical Phenomena↗
PubMed1997

Ultrasound as a screening study for gastro-oesophageal reflux in children.

A comparison of the abilities of ultrasound and scintigraphy to detect gastro-oesophageal reflux was made in 110 children (mean age 24.5 months) who were divided into groups A (n = 49) and B (n = 61). The former had scintigraphy first followed by ultrasound within about 30 min. For group B scintigraphy was also performed first, but the delay before ultrasound ranged between 1 and 30 days. In most patients (91/110) concordant results were obtained by the two modalities. The 19/110 discordant results can be explained by several plausible mechanisms. It is concluded that ultrasound should be employed much more frequently as an initial investigation when pathological reflux is suspected in children.

Age Distribution↗
PubMed1997

Is a gastric drainage procedure necessary at the time of antireflux surgery?

BACKGROUND: Gastroesophageal reflux is part of a generalized foregut motility disorder, which may also include delayed gastric emptying. With persistence of gastroesophageal reflux, or the presence of complications, including recurrent aspiration syndrome and esophageal stricture formation, surgical correction may be indicated. It is uncertain whether a procedure to resolve delayed gastric emptying is indicated at this time as well. METHODS: Sixty-seven children with proven gastroesophageal reflux had preoperative gastric emptying assessed using 99Technetium-Sn-colloid labelled milk. Delayed gastric emptying was defined as a gastric residual activity of more than 40% at 2 hours after feeding. The antireflux operation was a partial anterior fundoplication. Postoperative milk scans assessed the effect of surgery on gastric emptying. RESULTS: Gastric emptying at 2 hours improved overall from a median of 22% before surgery to 17% after surgery. In 17 patients delayed gastric emptying was identified before surgery; in 15 of those it returned to within normal limits after surgery. In 50 children with normal gastric emptying before surgery (gastric residual activity at 2 hours 16%), 14 (28%) showed delayed gastric emptying in the postoperative scan. CONCLUSIONS: Delayed gastric emptying is common in children who undergo surgery for gastroesophageal reflux disease. A partial anterior fundoplication antireflux operation improves gastric emptying to within normal limits in the majority (88%) in this group, rendering a synchronous gastric drainage procedure unnecessary.

Animals↗
PubMed1996

Intra-nuclear localization of two envelope proteins, gB and gD, of herpes simplex virus.

The envelopes of herpes simplex virus (HSV) particles are acquired from the inner nuclear membrane (INM) of the infected cell and virus-coded glycoproteins are present in the envelope of mature virions. Our ultrastructural study examined the process of virus envelopment and the targeting of two major viral glycoproteins, gB and gD, to the INM in HSV-infected human embryonic fibroblasts. It was shown that envelopment and transport of virus particles from the nucleus is facilitated by the formation of a dynamic tubulo-reticulum arising from the INM. Capsids were assembled in the nucleus and collected within INM tubules which protruded into the perinuclear space and thence into the cisternae of the endoplasmic reticulum (ER). Envelopment occurred by constriction and fusion of the tubular channel walls, releasing enveloped virions into the ER. Transport to the cell surface took place in membrane-bound compartments and probably followed the normal secretory pathway through the Golgi apparatus. Immunogold probes, tagged with specific monoclonal antibodies, were used to localize gB and gD during the process of virus maturation. Cytoplasmic membranes were not labelled, but probes bound inside the nucleus, mainly at sites of virus assembly. Labelling occurred on the nucleoplasmic side of the INM which surrounded capsids in the process of envelopment, but not on the outside of that membrane, although characteristic gB glycoprotein spikes were labelled on the envelopes of extracellular virus particles and on virions in trans-Golgi transport vesicles just prior to their release from the infected cell. gB was not detected on the surface of enveloped virions in the perinuclear space, or the cisternae of the ER or cis-Golgi, which suggests that the specific epitope was masked during that stage of intracellular processing. gD probes bound to virion envelopes and also to the tegument region of some particles found in both perinuclear and extracellular sites. We postulate the precursor core proteins for both gB and gD are transported first to the nucleus, and then, together with maturing capsids, are targeted to the INM, and later inserted into viral envelopes at the site of budding. Post-translational glycosylation of envelope proteins could occur as virus particles exit the nucleus and travel through the ER and Golgi compartments.

Cell Nucleus↗
PubMed1996

Clinical evaluation of the bone marrow imaging agent 99Tcm-phytate in the detection of bone metastases.

The aims of this study were to assess whether 99Tcm-phytate can detect metastatic skeletal lesions, and to compare it with 99Tcm-methylene diphosphonate (99Tcm-MDP) and 99Tcm-labelled human serum albumin nanocolloids (99Tcm-NC). Twenty-four patients with multiple bony metastases, investigated by 99Tcm-MDP whole-body scintigraphy, underwent 99Tcm-phytate bone marrow imaging. A separate bone marrow scintigram with 99Tcm-NC was performed in 20 of the patients. All of the metastatic lesions detected on the 99Tcm-phytate scintigrams exhibited photon-abundant foci only. Most of the 99Tcm-phytate scintigrams detected fewer metastatic lesions than the corresponding bone scintigrams. Visual comparison of the 99Tcm-NC images showed that 13 of 20 99Tcm-NC images were superior to the 99Tcm-phytate images in the detection of metastatic involvement of the skeleton. Thus 99Tcm-phytate should not be used as a bone marrow imaging agent for the detection of skeletal metastases.

Adult↗
PubMed1996

The natural progression of autonomic neuropathy and autonomic function tests in a cohort of people with IDDM.

OBJECTIVE: To test the natural progression of symptoms of autonomic neuropathy (AN) and function tests in subjects with IDDM. RESEARCH DESIGN AND METHODS: Seventy-six subjects with IDDM of < 10 years duration had cardiovascular autonomic reflex tests and were evaluated for signs and symptoms of AN. RESULTS: Fifty-seven subjects (66%) were available for restudy 9 years later (15 had died, 4 could not be located). Of the symptoms of AN, only gastroparesis increased in prevalence (P < 0.01). Of the five cardiovascular AN measures, only the R-R response to the Valsalva maneuver deteriorated (F[1,44] = 10.61, P < 0.01). CONCLUSIONS: The progression of AN in IDDM is monitored best longitudinally by the Valsalva maneuver because of the small variance ratio in repeated measures. Prevalence rates can be monitored by expiration-to-inspiration R-R or Valsalva ratios. Most clinical signs and symptoms of AN do not progress, underscoring the need for objective and quantitative autonomic function tests to identify people at risk for premature death.

Adolescent↗
PubMed1995

Transit through the distal quarter of the oesophagus in young children.

The transit time of 800 individual boluses through the distal quarter of the oesophagus was measured in 33 scintigraphic oesophageal studies which had been selected as typifying normal swallows in children. The results show that, in children, transit time through the distal quarter including the lower oesophageal sphincter is normally less than 2 seconds and that transit tends to be slower during the first 4 seconds after onset of swallowing.

Deglutition↗
PubMed1995

The "Fisherman's Waders" sign in a bone scan of inferior vena cava thrombosis associated with nephrotic syndrome.

This paper presents a 61-year-old male patient with nephrotic syndrome, hypercoagulability and IVC thrombosis. Increased soft tissue uptake below the level of the mid chest was seen in his bone scan. The term "Fisherman's Waders" sign is suggested for this finding, whose recognition may permit the identification of inferior vena cava obstruction in bone scans. The existence of a cavo-portal shunt was also confirmed by dynamic scintigraphy.

Blood Coagulation Disorders↗
PubMed1995

Lateral neck imaging for spatial localization of parathyroid tissue.

Two patients with an ectopic parathyroid adenoma are described. In both cases the lesions were clearly demonstrated in an anterior view on T1-201/Tc-99m scintigraphy, but were not identified during the first surgical exploration. Failure to identify the ectopic adenoma at surgery in the second patient led to oblique and lateral views being obtained. These views permitted correct depth localization. We, therefore, believe that lateral and oblique views can be of assistance in improving preoperative localization of an ectopic parathyroid adenoma.

Adenoma↗