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Biomedical subjects

S Marks

Publications and source records attributed to S Marks.

At least 19 recordsLinked to original sources
PubMed1991

Ultrasound attenuation of the calcaneus: a sensitive and specific discriminator of osteopenia in postmenopausal women.

Recent studies have evaluated techniques for estimating bone mass without radiation. The present study compares broadband ultrasound attenuation of the calcaneus and bone densities of the femoral neck and the lumbar spine in 17 normal women and 41 women with osteoporosis. Twenty of the osteoporotic women had spine (n = 16) or femoral neck (n = 4) fractures. There was a significant decrease in the broadband ultrasound attenuation (P less than 0.001) in women with osteoporosis compared with normal women. The osteoporotic women also showed a decrease in vertebral (P less than 0.0001) and femoral neck (P less than 0.0001) densities compared with normal women. At 63 dB/MHz, the sensitivity and specificity of broadband ultrasound attenuation for decreased bone mineral density with or without fractures were 76%. All women with fractures had a broadband ultrasound attenuation less than 72 dB/MHz. This corresponded to a specificity of 41%. To determine whether broadband ultrasound attenuation correlated with trabecular bone volume, samples of cadaver calcaneus were analyzed. The histologic determination showed a significant correlation between broadband ultrasound attenuation and trabecular bone volume (r = 0.992, P = 0.008). These results suggest broadband ultrasound attenuation of the calcaneus reflects bone mass and can be used as a safe and sensitive indicator for decreased axial bone density.

Absorptiometry, Photon↗
PubMed1991

Central nervous system infarction related to cocaine abuse.

BACKGROUND: Cocaine use in the United States has reached epidemic proportions, and increased availability of "crack" since 1983 has noticeably increased the incidence of neurovascular complications. In this report, we examine the relationship between cocaine use and ischemic infarct. SUMMARY OF COMMENT: This study reports 18 cases of ischemic cerebrovascular events, which occurred among 15 men and three women aged 21-47 years who were evaluated in a 2-year period. Clinical presentations include thirteen cases with hemispheric infarcts, two brain stem strokes, two anterior spinal artery infarcts, and one with both hemispheric and cerebellar infarcts. Nine patients smoked crack, four snorted cocaine, and three injected it intravenously. In two cases, the route of administration could not be determined. Two patients died, but the other survived with various degrees of neurological deficit. CONCLUSIONS: Traditional risk factors for strokes were identified in only six patients, suggesting that these factors are not necessary for the occurrence of a cocaine-related infarct. Multiple overlapping mechanisms may be responsible, including vasospasm, sudden onset of hypertension, myocardial infarction with cardiac arrhythmias, increased platelet aggregation, and vasculitis.

Adult↗
PubMed1990

Transurethral incision of the bladder neck and prostate.

Between March 1983 and December 1988, 66 men 50 years old and older with symptomatic bladder outlet obstruction underwent transurethral incision of the bladder neck and prostate. Patients selected for incision had a small, clinically benign, prostate and peak urinary flow rate of less than 15 ml. per second. Preoperative and postoperative evaluation included symptom questionnaires and uroflowmetry. A single midline incision was made extending from the bladder neck to the verumontanum. Results were available in 64 of the 66 men who underwent the procedure with a mean followup of 2.24 years. Mean symptom scores decreased from 9.66 preoperatively to 4.59 postoperatively (p less than 0.001) and peak urinary flow rates increased from 7.4 to 14.7 ml. per second (p less than 0.0001). Antegrade ejaculation was preserved in 83.3% of the men who preoperatively had antegrade ejaculation. Subsequent transurethral resection of the prostate was required in 5 patients (7.6%). With a mean followup of greater than 2 years transurethral incision of the bladder neck and prostate was effective in treatment of bladder outlet obstruction caused by a small prostate while maintaining antegrade ejaculation in the majority of patients.

Follow-Up Studies↗
PubMed1989

The state, class and the allocation of health resources in southern Africa.

In Africa the literature specifically linking the state, class and the allocation of health resources is sparse, and the evidential base for health research is inadequate and difficult to interpret. This paper looks at some of the ways in which state, class and health may be related in southern Africa. The region provides useful comparisons because of the starkness of the relationships between class and race and disease patterns and health care in much of the sub-continent; the different types of state and class structure within southern Africa; and the changes in ideology and to some extent health practice which came with the political independence of some of its component parts. Using both historical and contemporary data, it pinpoints the importance of analysing the specific and changing form of the state in the different countries of the region, in order to understand the social determinants of disease and the allocation of health resources, and looks at the significance of class, race, ethnicity and gender in the incidence of health and the state's response. It highlights the specific colonial legacies, continuing imperial linkages and location of countries in the international division of labour which inhibit changes in health care. Within the region, the migrant labour system and South Africa's aggressive policies of destabilisation create particular problems for weak states and for individuals within them attempting to implement more progressive health care programmes. The paper also argues that the ideological role played by health care has to be understood, and shows the diverse uses to which it is put across the region. The paper concludes that while the position of the state in the international and regional economy, its specific form and the nature of its class relations are predictors in some sense of health and health care, a variety of micro-level political and social decisions and mediations have also to be taken into account. While most of the countries of the region are in some sense part of the 'periphery', and a product of colonialism, these labels are insufficient to explain the differences between them in terms of disease patterns and health care systems. The specificities of internal social dynamics, local class ethnic and gender struggles and political conflicts are also crucial.

Africa, Southern↗
PubMed1989

Seeing either the forest or the trees: dissociation in visuospatial processing.

Traditionally, visuospatial processing has resisted fractionation into functional substrates. Recently, however, it has been shown that the brain honors the distinction between global and local processing of hierarchical visual stimuli: unilateral left hemisphere brain-damaged subjects were impaired in their ability to draw the local forms of a hierarchical design, whereas right hemisphere-damaged patients demonstrated the opposite pattern (Delis, Robertson, & Efron, 1986; Delis, Kiefner, & Fridlund, 1988). The present study reports a similar pronounced dissociation in hierarchical visual processing but in quite different populations and in the absence of focal structural brain damage. Mentally retarded subjects with Williams Syndrome are considerably more impaired in global relative to local analysis, whereas subjects with Down Syndrome display the opposite pattern. These results, in concert with other neuropsychological data, are provocative because they suggest that certain cognitive deficits may cluster even in the absence of frank cerebral damage, just as they cluster following insult to one hemisphere. These findings should provide clues to the interrelationship of components of visuospatial processing and other cognitive functions.

Adolescent↗
PubMed1989

Will chromosome karyotyping of meningiomas aid prediction of tumour recurrence?

Cytogenetic studies over many years have established absence or deletion of chromosome 22 as a common finding in meningiomas. Enormous karyotypic variation is recognised: an abnormal hyperdiploid clone can occur in a histologically benign meningioma. The cytogenetic, histopathological and macroscopic findings in 13 meningiomas of a prospective study are presented. Where the neuropathologist reported the presence of malignant change, a cytogenetically abnormal clone was more common in short-term culture of the tumour tissue. Histologically benign meningiomas showed great cytogenetic variation, from normal chromosomes to hyperdiploid clones with extensive karyotypic abnormality indicating malignant change. We suggest the addition of cytogenetic findings to histopathological features in assessing 'malignancy' in meningiomas and the risk of recurrence or regrowth.

DNA, Neoplasm↗
PubMed1988

Apartheid and health in the 1980s.

The last 5 years have seen dramatic developments in South Africa, with wide-based internal political struggles and international pressure forcing the government into a well publicized if temporary series of reforms. Yet this has not been paralleled by any substantial improvement in the health conditions of the majority of the population. Apart from improvements in black infant mortality in some urban areas, the health gap remains, a material expression of the social inequality that is part of the definition of apartheid. Black children continue to die from preventible afflictions at about 10 times the rate of their white counterparts. Maternal deaths among women classified as black, coloured or Asian continue to occur, mostly due to septic abortions. At national level, blacks are nearly 30 times more at risk of being diagnosed to have tuberculosis than whites, with some age groups being at still worse risk. Black children under the age of 4 years in Cape Town in 1984 were 205 times more likely to have tuberculosis than their white counterparts. The last 5 years has also seen a revival of rhetoric echoing the international support for primary health care in the 1970s, but health care processes have not been modified to cope with the continuing racial stratification of disease and access to health care. A move towards privatization of the health services has only benefited a few.

Black People↗
PubMed1988

Surgical therapy of chronic glaucoma in aphakia and pseudophakia.

Most glaucoma surgical procedures are less successful in aphakic or pseudophakic eyes. The authors reviewed 91 consecutive initial glaucoma procedures in aphakic patients from 1979 to 1986 to determine successful outcomes and complications. Success was defined as an intraocular pressure (IOP) of at least 30% below the preoperative value and less than 21 mmHg, less than 2 lines of Snellen acuity loss, and no further surgical intervention. At 9 months, success rates were: trabeculectomy, 4 of 15 patients; cyclodialysis, 3 of 20 patients; neodymium:YAG (Nd:YAG) cyclophotocoagulation, 1 of 8 patients; cyclocryotherapy, 9 of 22 patients; anterior chamber tube shunt (Schocket procedure), 3 of 6 patients; and argon laser trabeculoplasty, 2 of 20 patients. Severe complications included phthisis bulbi in 11% of cyclocryotherapy and severe visual loss in 20% with cyclodialysis and 14% with cyclocryotherapy. Results confirm the difficulty of surgical therapy in these patients.

Aged↗
PubMed1987

Merkel cell carcinoma.

Merkel cell carcinoma is a rare malignant neoplasm of the skin which is locally invasive and frequently metastasizes to lymph nodes, liver, lungs, bone, and brain. Computed tomographic and pathologic findings in an elderly woman with Merkel cell carcinoma of the buttock and regional nodal metastasis are reported. The presence of calcitonin and neuron-specific enolase within the tumor supports the theory that Merkel cell carcinoma is a neuroendocrine tumor derived from the APUD (amine precursor uptake and decarboxylase) system.

Aged↗
PubMed1986

Renal fascial pathway: posterior extension of pancreatic effusions within the anterior pararenal space.

Retrorenal extension of pancreatic effusion or phlegmon associated with pancreatitis has been described frequently and is generally considered to represent extension of these processes from the anterior into the posterior pararenal space. A series of meticulous cadaveric dissections (n = 8) and a review of a large number of patients with pancreatitis (n = 53) show that these posterior collections actually represent extension of pancreatitis from the anterior pararenal space to a potential space between the laminae of the posterior renal fascia. Of 40 patients with posterior extension of pancreatic effusion or phlegmon, interfascial involvement was observed in all 40 and was bilateral in nine (23%). True involvement of the posterior pararenal space was uncommon, as was extension into the perirenal space. This phenomenon appears as a continuum of the well-described thickening of the renal fascia secondary to pancreatitis. It can be explained by new observations of the relationships between the fascia of Gerota and the lateroconal fascia.

Cadaver↗
PubMed1978

Evaluation of three antibiotic programs in newborn infants.

Emergence of gram-negative bacteria resistnant to a number of antibiotics in intensive care nurseries for neonates emphasizes the need for alternatives in antibiotic combinations. One commonly used combination, gentamicin-ampicillin, and two newer combinations, tobramycin-cephalothin and amikacinampicillin, were evaluated prospectively in 60 newborns in such a nursery. Subjects were randomly assigned to one of the above therapy groups. Dosages in mg/kg.d were 100 for ampicillin and cephalothin, 6 for gentamicin and tobramycin and 15 for amikacin. Aminoglycoside serum concentrations, clinical tolerance and toxicity were monitored. Aminoglycoside concentrations after intravenous administration of the drugs were within the expected range (gentamicin and tobramycin 4 to 6 microgram/mL and amikacin 15 to 20 microgram/mL). There was no hematologic, renal or hepatic toxicity attributable to antibiotic therapy and the combinations were tolerated equally; no bilirubin displacement was detected in vitro or in vivo.

Amikacin↗
PubMed1978

Human triclonal anti-IgG gammopathy. III. Determination of the clonal persistence of the IgM autoantibody for a four and one-half year period.

The persistence in the structure of IgM anti-IgGs obtained from the serum of a patient (Gil) with Felty's syndrome was studied. Co-isoelectric focusing experiments showed that intact IgM from early (1970) and late (1973) sera, and their heavy and light chains had identical isoelectric points (pI). Light chains from 1970, 1973, and 1974 IgM-Gil had identical amino terminal amino acid sequences and belonged to the v Kappa II light chain subgroup. Specificity studies of IgM-Gil isolated from serum obtained in 1970, 1972 and 1974 showed identical patterns of reactivity with IgG and IgG subunits of all gamma chain subclasses. Finally, by haemagglutination-inhibition, antisera specific for idiotypic determinants of IgM-Gil-1970 were shown to be shared by IgM from 1970, 1972 and 1974 sera. The data support the notion that autoantibody-producing cell clones persist unaltered during the course of an untreated autoimmune disease, in this instance for 4 1/2 years.

Amino Acid Sequence↗