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Biomedical subjects

G Smith

Publications and source records attributed to G Smith.

At least 487 records · Page 27Linked to original sources
PubMed1992

J-wire facilitates retrograde manipulation of ureteric calculi prior to extracorporeal shock wave lithotripsy.

During a 13-month period, 55 patients underwent attempted retrograde manipulation for ureteric lying above the pelvic brim. The mean stone burden was 11 mm (range 5-21); 41 stones (75%) were primary ureteric calculi and 14 (25%) were fragments resulting from extracorporeal shock wave lithotripsy to renal calculi. The method of retrograde manipulation was recorded prospectively. Retrograde flushing through an 8F angiography catheter with a mixture of saline and lignocaine gel was successful in 27 patients (49%). The insertion of a J-wire through the angiocath allowed for successful manipulation in a further 17 patients (31%). Retrograde manipulation was impossible in 11 patients (20%). There were 4 complications (7%), none attributable to the use of a J-wire.

Adolescent↗
PubMed1992

A comparison of glycine, sarcosine, N,N-dimethylglycine, glycinebetaine and N-modified betaines as liposome cryoprotectants.

Glycinebetaine has previously been shown to be effective at reducing leakage from liposomes which are frozen then thawed. This study involved the preparation of a series of N-modified betaines and the comparison of their cryoprotective activities with those of glycine, sarcosine, N,N-dimethylglycine and glycinebetaine. All the compounds investigated, with the exception of (dimethyloctylammonio)acetate, reduced the degree of leakage, after freezing and thawing, with additive concentrations up to 0.6 M. Reducing the degree of N-terminal methylation of glycinebetaine appeared to increase the leakage from liposomes at additive concentrations between 0.2 and 0.6 M. (Dimethylethylammonio)acetate, (dimethylisopropylammonio)acetate and (N,N,N',N'-tetramethylethylenediammonio)-N,N'-diacetate appeared to be no more effective than glycinebetaine, whereas improved protection was afforded by (triethylammonio)acetate and (diethylmethylammonio)acetate at most concentrations. This study demonstrates that the cryoprotective activity of glycinebetaine may be improved with modifications to the N-terminal.

Amaranth Dye↗
PubMed1992

Comparative evaluation of a chemiluminescent DNA probe and an exoantigen test for rapid identification of Histoplasma capsulatum.

A chemiluminescent DNA probe (Accuprobe) assay developed by Gen Probe, Inc., for the rapid identification of Histoplasma capsulatum was evaluated and compared with the exoantigen test by using 162 coded cultures including Histoplasma capsulatum var. capsulatum, Histoplasma capsulatum var. duboisii, Histoplasma capsulatum var. farciminosum, Blastomyces dermatitidis, Coccidioides immitis, Paracoccidioides brasiliensis, and morphologically related saprobic fungi. Each test uses a chemiluminescent, acridinium ester-labeled, single-stranded DNA probe that is complementary to the rRNA of the target organism. Lysates of the test cultures were prepared by sonication with glass beads and heat treated. After the rRNA was released from the target organism, the labeled DNA probe combined with the target H. capsulatum rRNA to form a stable DNA-RNA hybrid. A hybridization protection assay was used, and the chemiluminescence of hybrids was measured initially with a Leader 1 luminometer as relative light units and later during the investigation with a probe assay luminometer as probe light units. Of the 162 coded mycelial cultures tested by the Accuprobe assay, 105 were identified as H. capsulatum. The test could be performed with an inoculum of a few square millimeters (1 to 2 mm2) of growth. In the primary evaluation, the Accuprobe identified 103 of the 105 cultures as H. capsulatum within 2 h. The remaining two cultures, contaminated with bacteria, had to be purified before the Accuprobe assay identified them correctly as H. capsulatum. Since each coded culture was concurrently tested for H. capsulatum, B. dermatitidis, and C. immitis exoantigens, the identification of all three dimorphic pathogens was provided simultaneously. Of the 162 coded cultures tested, 105 were identified by the exoantigen test as H. capsulatum, 12 were identified as B. dermatitidis, 13 were identified as C. immitis, and 32 were negative for H. capsulatum, B. dermatitidis, and C. immitis. The bacterial contamination in two isolates did not interfere with the exoantigen testing. The exoantigen test required 7- to 10-day-old colonies and required 48 to 72 h of incubation before definitive identification was obtained.

Antigens, Fungal↗
PubMed1992

Positron emission tomography imaging-directed stereotactic neurosurgery.

The diagnostic yield of stereotactic biopsies depends upon safely sampling the most representative regions of masses. Potentially, localization information presently available from CT and MR scans might be improved by considering regional levels of cerebral metabolism by PET. In 10 selected stereotactic biopsies of intracranial mass lesions, PET scans were obtained using the Siemens CTI system; the Kelly-Goerss Compass system was used as the stereotactic development platform. PET-[18F]-fluorodeoxyglucose (FDG) images provided clinically significant information by appropriately directing biopsy efforts when CT and MRI was inconclusive or misleading. PET-FDG images can be successfully incorporated into routine image-directed stereotactic surgery.

Astrocytoma↗
PubMed1992

A consumer-operated case management project.

The idea that patients and former patients might themselves be involved in service delivery has become increasingly popular in recent years. Once viewed as an expression of patient protest without clinical merit, self-help services are now, at least in some places, accepted and endorsed by mental health planning authorities. This month's guest columnists describe the philosophical underpinnings of a state-funded consumer-operated case management program in Oregon and discuss both the hope and some of the potential difficulties that such an experimental effort may generate.

Activities of Daily Living↗
PubMed1992

The effect of accommodation on retinal image size.

The apparent size of an object is diminished when accommodation of the eye moves inward to a position closer to the observer than to a viewed object. This phenomenon is called accommodation micropsia. Using schematic eyes, we investigated change in retinal image size caused by a change in accommodation. The use of schematic eyes is also discussed and is justified. The calculated magnitude of this diminution for four schematic eyes ranged from unity at infinity to a maximum of 0.98 (-2%) at about 12.0 diopters (D). For distances at which accommodation micropsia is typically observed (about 2.0 D), retinal minification is less than 0.997 (-0.3%). Thus changes in the size of the retinal image attributable to accommodation are virtually negligible when compared with the observed reduction of 3% to 33%. This suggests that accommodation micropsia is mediated almost entirely by processes other than those involving the optics of the eye.

Accommodation, Ocular↗
PubMed1992

Memory function in normal aging.

We evaluated memory function in a group of 161 community-dwelling, cognitively normal individuals aged 62 to 100 years recruited as part of the Mayo Clinic Alzheimer's Disease Patient Registry. We used the Free and Cued Selective Reminding Test and the Rey Auditory Verbal Learning Test to evaluate two aspects of memory function thought to be sensitive to the effects of aging: learning (acquisition) and delayed recall (forgetting). The results were quite consistent and demonstrated that learning or acquisition performance declines uniformly with increasing age but is not related to education. Delayed recall or forgetting, however, remained relatively stable across age when adjusted for the amount of material initially learned. These findings are relevant for assessing normal memory function relative to the early impairments found in dementia and form a baseline against which memory performance can be assessed by the clinician. In particular, suspicion regarding a disorder of brain function affecting memory processes should be raised if learning performance declines more rapidly than expected or if delayed recall is impaired to any significant extent.

Aged↗
PubMed1992

Modeling the power of the aging human eye.

A hypothesis is presented that may explain why the aging eye does not become myopic with age. The power of the eye lens is predicted with a modeling approach to determine how the form of the refractive-index gradient within the lens can change to maintain a constant power in spite of age-related curvature increase. Methods used include published age-dependent data on the optical parameters of the eye, a mathematical model of the lens based on elliptical isoindicial contours, and a refractive-index profile that can be expressed as a power series in the distance from the lens center. The kinds of change in profile required to prevent the eye from becoming myopic as its lens grows are shown.

Aging↗
PubMed1992

Molecular genetics of the human cytochrome P450-dependent monooxygenases.

In this work, the role of genetic as well as environmental factors in determining cytochrome P450 isozyme levels in man have been studied. Simple DNA based assays for the identification of individuals nulled at the CYP2D6 locus are described and have been applied to investigate whether this gene defect is associated with altered cancer susceptibility. In contrast to literature reports, in no cancer type were poor metabolizers underrepresented, indeed in several cancers the mutant allele frequency was increased. A model using human tumours grown as xenografts is described that should help elucidate the factors which regulate P450 levels in man.

Chromosome Mapping↗
PubMed1992

A training project helps the poor. A rural healthcare facility offers job training, gains employees.

As poor Americans look for work, healthcare facilities face a shortage of workers. One facility, Saint Francis Medical Center in Grand Island, NE, found a way to help some of the area's financially disadvantaged persons receive technical training and employment as it eased its own personnel shortage. Saint Francis leaders assembled a team of representatives from the hospital's staff, the Greater Nebraska Job Training Program, Lincoln, and Central Community College, Grand Island, to establish the Rural Allied Medical Business Occupations program. The team reviewed several job descriptions to help it decide which jobs to include in the program and surveyed area hospitals to ensure the positions selected were experiencing shortages. The program received a grant as a demonstration project from the U.S. Department of Education. After identifying participants who had the aptitudes and interests for the jobs, the Rural Medical Allied Medical Business Occupations program arranged for participants' training and assistance with items such as tuition, child care, and transportation. Participants received training at Central Community College and at Saint Francis Hospital. Saint Francis Medical Center deemed the program a success. The hospital has hired seven healthcare workers who would not have been available if they had not been trained through this program. Moreover, the program provides yet another way for the hospital to help fulfill a major portion of its mission: to help the poor.

Allied Health Occupations↗
PubMed1992

Sources and types of referral to a haematology department.

An audit was undertaken of the case notes of all new outpatients referred to the haematology department at the Leeds General Infirmary over a one-year period. The source, reason for referral, final diagnosis and outcome were determined in each case, along with essential biographical details. The results show that general practitioners initiated over half of all referrals, often prompted by written comments from a hematologist on a full blood count advising them that further tests were required. Almost a third came from other departments at the study hospital and the remainder originated from hospitals outside the district. Most general practitioner referrals were made with a request for a diagnosis. Hospital initiated referrals were more likely to have a final diagnosis of a malignant haematological disease, whereas those from general practice tended to have benign or self-limiting conditions. Ninety-one per cent of patients referred had an abnormality. There were low numbers of both clinic defaulters and those patients required to be re-referred to other specialties. These results suggest that the high quality of referrals is largely due to the general practitioner's decision to refer patients based on the full blood count result. This often occurs after discussion with haematology medical staff. The possible impact of the government's White Paper proposals on this outpatient service is discussed.

Adolescent↗
PubMed1992

Hip pain caused by buttock claudication. Relief of symptoms by transluminal angioplasty.

Two patients with severe hip pain proved to have buttock claudication resulting from isolated stenosis of the hypogastric artery. This diagnosis may be elusive if distal pulses are palpable, directing the clinician's suspicion away from vascular pathology. Diagnosis requires angiography. The patients were successfully treated by transluminal angioplasty. Angioplasty is the initial treatment of choice for these patients because the hypogastric artery is usually readily and safely accessible from either the femoral or axillary artery.

Aged↗
PubMed1992

Developmental biology and migration of Strongyloides ratti in the rat.

Most recent authors suggest that larvae of the threadworm, Strongyloides ratti, migrate from a cutaneous infection site to the small intestine via the naso-frontal region of the head. However, the proportion of larvae that successfully reach the intestine having followed this pathway had not been determined. Using compartmental analysis we have obtained a comprehensive quantitative description of larval migration during a primary infection of rats with S. ratti. Mean residence times in organs through which larvae migrate were calculated and the proportion of the larvae arriving in the small intestine via the head was estimated as 0.5-0.86, depending on the mathematical model used to generate the estimate. With 50% or more of successful larvae using this pathway it is now reasonable to recognize the "head route" as an important migratory pathway for larvae traveling to their intestinal predilection site. During the first 12 hr in the host, larvae were difficult to recover from the skin and subjacent muscles of the infection site. Apparently, upon invading a host, many larvae enter a quiescent phase during which Baermannization, an active recovery technique, fails to recover them. Infections were short-lived, with the daily finite mortality rate for adult worms attaining 50-80% on day 16 of infection.

Animals↗
PubMed1992

Effects of flurbiprofen and suprofen on the miotic activity of 1% acetylcholine and 0.01% carbachol.

The nonsteroidal antiinflammatory agents (NSAIAs) flurbiprofen and suprofen applied topically to reduce miosis may counteract the desired effects of miotics used during ocular surgery. In a pigmented rabbit model, 1% acetylcholine was shown to cause a greater, significant initial (for the first 30 minutes) constriction (P less than .05) than 0.01% carbachol in eyes pretreated with flurbiprofen and suprofen. From 2 to 8 hours, NSAIA pretreatment had a greater miotic effect with carbachol than with acetylcholine. There were no significant differences between flurbiprofen and suprofen on the miotic effect of carbachol or acetylcholine.

Acetylcholine↗