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Biomedical subjects

D Gold

Publications and source records attributed to D Gold.

At least 37 records · Page 2Linked to original sources
PubMed1999

The indigenous Sea Gypsy divers of Thailand's west coast: measurement of carbon monoxide in the breathing air.

Approximately 400 indigenous divers live and work on Thailand's west coast. They dive with surface supplied air from primitive compressor units mounted on open boats which measure from seven to 11 meters in length. It was suspected that carbon monoxide was present in the breathing air of at least the gasoline-driven compressor units. To determine the presence of carbon monoxide gas in the breathing air, compressed air from the compressor was pumped through the diver air supply hose through a plenum (monitoring) chamber established on the boat. After a compressor warm-up of 15 minutes, the diving air was measured with the boat at eight different bearings to the wind, each 45 degrees apart at intervals of five minutes. Three of the four gasoline-driven compressor units tested showed presence of carbon monoxide in the breathing air. One diesel-driven unit showed a very low concentration of carbon monoxide (3-4 ppm) and six diesel-driven units showed no detectable carbon monoxide. Although not tested, diesel exhaust emissions could also enter the breathing air by the same route. A locally made modification to the compressor air intake was designed and successfully tested on one gasoline-driven compressor unit. An information sheet on the hazards of carbon monoxide as well as on the modification has been developed for distribution among the villages.

Air↗
PubMed1999

The indigenous fisherman divers of Thailand: in-water recompression.

BACKGROUND: The Urak Lawoi, part of the Sea Gypsies of Thailand, have been diving using surface-supplied compressed air for more than 30 years. Their dive sites range from one hour to several days from their villages. Similar to other indigenous fisherman divers, the Urak Lawoi suffer from a high incidence of decompression illness. Their methods of in-water recompression were investigated. METHODS: In December 1998, available divers in two Urak Lawoi villages were asked if they had ever been treated using in-water recompression following decompression illness. If the divers responded positively, a questionnaire-based interview was carried out. Divers were asked to recall the cause of the accident, their diving patterns of the day, the parts of the body affected, the depths and times of in-water recompression and whether the problems were resolved as a direct result of this action. RESULTS: Eleven divers, aged 19-52, were interviewed. Causal factors listed by the divers included diving pattern 55% (6/11), rapid ascent 27% (3/11), and equipment failure 18% (2/11). Divers were recompressed in water using surface-supplied compressed air. The time between surfacing from the accident-related dive and being put back in the water ranged from immediately to 60 minutes. Depth and duration of in-water recompression ranged from 4 to 30 meters and 5 to 120 minutes. Outcomes reported by the divers were: improved or resolved at depth with no return of symptoms at surface in 64% (7/11), improved or resolved at depth with a return of symptoms at surface in 18 (2/11), and not resolved at depth in 18% (2/11). DISCUSSION: Health-care workers in the villages may be able to provide basic first aid but, for some villages, a medical doctor may be as much as 10 hours away and a recompression facility as far as 16 hours in good weathier. In-water recompression has, within the diving population, proved to be an appropriate first-aid measure for decompression illness. A future project activity will develop consensus guidelines for determining under what circumstances in-water recompression using surface-supplied air should be carried out and identify appropriate methods that the Urak Lawoi can apply.

Adult↗
PubMed1998

A role for the hippocampal formation in implicit memory: a 3-D PET study.

The apparent preservation of word priming effects in amnesia has been interpreted as supporting the view that implicit memory depends on brain systems that are independent of mesial temporal lobe structures which are in part responsible for explicit memory disorders. Nevertheless, a number of studies have demonstrated word priming deficits in amnesic patients relatively to normal subjects, suggesting that such structures may also be involved in implicit memory. To determine whether one such structure, the hippocampal formation, is a component of the brain system subserving word priming, a 3-D PET study was carried out in 13 normal individuals. Encoding was carried out using the brief multiple presentation technique, a procedure that allows one to effectively circumvent contamination of implicit memory tasks by explicit memory strategies. Results revealed that word priming was indeed associated with an activation of the right hippocampal formation. This finding of an hippocampal involvement in word priming calls into question the notion of absolute dissociability between the brain systems underlying performance on various explicit and implicit memory tasks.

Adolescent↗
PubMed1998

Beyond retinal screening: digital imaging in the assessment and follow-up of patients with diabetic retinopathy.

Many screening methods are available for detecting diabetic retinopathy. However, once patients develop retinopathy, it is unclear as to what method should be used for their review. We describe a novel and integrated system for the screening and treatment of diabetic retinopathy using high street optometrists for primary screening and digital imaging as a secondary screening tool, with referral to a joint retinal clinic only where ophthalmological intervention may be required. Of 3586 patients screened by optometrists, 328 were classified as having moderate/severe pre-proliferative retinopathy or diabetic maculopathy. Patients with proliferative retinopathy (1% of the total) were recalled directly to the joint retinal clinic. A consecutive sample (281) of these patients, together with a further 100 classified by the optometrists as having no or background retinopathy were compared using digital images and standard 35 mm colour transparencies. These, together with the original optometrist reports, were reviewed independently and individually by an ophthalmologist. A further sample of 124 patients who had undergone both digital imaging and ophthalmologist slit-lamp examination were also compared. Comparison of 35 mm colour transparencies with optometrist reports showed the latter had a sensitivity for detecting sight-threatening retinopathy (STR) of 62%, a specificity of 84%, and a kappa score of 0.62. The results for digital images were 90%, 97%, and 0.90, respectively, although the extent of retinopathy was under-reported in 10 patients. With ophthalmologist slit-lamp examination as the gold standard, the sensitivity of digital imaging was 90% with a substantial level of agreement between them (kappa 0.61). We conclude that digital images provide an efficient method for the follow-up of patients with established or previously treated retinopathy.

Adult↗
PubMed1997

Assessment of the viability of Schistosoma mansoni schistosomula by comparative uptake of various vital dyes.

Of various vital dyes used to assess schistosomula viability, toluidine blue enabled differential counting of the schistosomula on microscope slides but not in culture wells, whereas methylene blue could be added directly to the schistosomula suspension in culture wells of microtiter plates. Toluidine blue uptake by dead parasites was very fast. It mostly also partially stained damaged but not dead organisms. Its main disadvantage was rapid, nonspecific staining of live schistosomula, requiring prompt counting of a preparation and additional reliance on motility for assessment of viability. Methylene blue staining of dead worms was slower, but it did not stain the live worms until about 1 h after dye application, enabling its addition to a series of preparations for consecutive counting. It did not always stain flattened, dead schistosomula or it stained them an uncontrasting pale blue. This dye remarkably induced movement in seemingly inert and probably damaged worms, thus enabling determination of viability even following poor staining or a lack of staining.

Animals↗
PubMed1997

Word priming with brief multiple presentation technique: preservation in amnesia.

Many studies have shown relative preservation of word priming in subjects with mild amnesia, but some decrease in severe amnesia. This calls into question the degree of separation between implicit and explicit memory. Possible contamination of implicit memory tasks by impaired explicit memory strategies might be obscuring the actual dissociation between the two memory systems. We have developed a method of circumventing explicit memory contamination by using brief duration repeated primes below the awareness threshold of subjects. We have used this approach to evaluate the status of word priming in densely amnesic subjects. One group of amnesic subjects with alcoholic Korsakoff's syndrome and one group of normal elderly control subjects were tested for word priming on a speeded category membership decision task. Implicit or explicit encoding procedures were used in three different experiments. Results demonstrated that brief multiple presentation of words can offer a means of producing word priming in the absence of explicit recognition or recall of the primed words in both amnesic subjects and normal elderly control subjects. Moreover, there was no significant difference in the magnitude of the priming effect between these groups in the three experiments. These findings show that amnesic subjects can exhibit normal levels of word priming. They also suggest that amnesics retain the capacity to encode, store and retrieve information implicity, e.g. unintentionally.

Aged↗
PubMed1997

Immunohistochemical and genetic evidence of myeloperoxidase involvement in multiple sclerosis.

The myeloperoxidase enzyme (MPO) is expressed specifically in myeloid cells and catalyzes the formation of hypochlorous acid and other cytotoxic oxidants. We previously reported that two alleles of MPO exist which differ in promoter strength due to a base difference in an Alu-encoded hormone response element. The present study shows that the higher expressing MPO genotype is overrepresented in early onset multiple sclerosis in females, implicating MPO in this demyelinating disease. Contrary to the general conception that macrophages lack MPO, immunohistochemical analysis shows that MPO is present in microglia/macrophages in and around MS lesions as shown by colocalization with major histocompatibility antigens HLA-DR and phagocytized myelin. Also, MPO mRNA sequences are detected in cDNA derived from isolated human adult microglia. This is the first evidence that MPO is present in microglia/macrophages at MS lesions, that MPO gene expression occurs in microglia and that MPO plays a role in MS pathogenesis as shown by the allelic disequilibrium in early onset disease.

Adult↗
PubMed1995

A role for CD95 ligand in preventing graft rejection.

Testis is a remarkable immune-privileged site, long known for its ability to support allogeneic and xenogeneic tissue transplants. Here we have investigated the molecular basis for testis immune privilege. Testis grafts derived from mice that can express functional CD95 (Fas or Apo-1) ligand survived indefinitely when transplanted under the kidney capsule of allogeneic animals, whereas testis grafts derived from mutant gld mice, which express non-functional ligand, were rejected. Further analysis of testis showed that CD95 ligand messenger RNA is constitutively expressed by testicular Sertoli cells, and that Sertoli cells from normal mice, but not gld mice, were accepted when transplanted into allogeneic recipients. CD95 ligand expression in the testis probably acts by inducing apoptotic cell death of CD95-expressing, recipient T cells activated in response to graft antigens. These findings indicate that CD95 ligand could be used to create immune-privileged tissue for a variety of transplant uses.

Animals↗