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Biomedical subjects

S Clifford

Publications and source records attributed to S Clifford.

At least 19 recordsLinked to original sources
PubMed2001

Diversity and heterogeneity in mitochondrial DNA of North American populations.

Variation in the mitochondrial DNA (mtDNA) control region as detected by sequence-specific oligonucleotide (SSO) probes is described for 2282 individuals from African-American, European-American, and Hispanic subpopulations from five broadly defined regions of North America (Northeast, Southeast, Central, Northwest, Southwest). Population diversity estimates were uniformly high for all subpopulations and for each major ethnic group. Only the Pennsylvania Hispanic group was remarkable with respect to its mitochondrial DNA types, having both six low frequency population specific types (ranging from 1.2-8.6%) and three high frequency shared types (10-20% each). There was no statistically significant subpopulation heterogeneity present within any of the three major groups at either the subpopulation level or the regional level (p > 0.01). However, statistically significant heterogeneity was measured when comparing the three major groups to each other, with the variance component attributable to this large division accounting for 18.60% of the total variance (p < 0.001). Overall mtDNA is a satisfactory forensic typing locus within broadly defined African-American, European-American, and Hispanic groups from North America, based on the high diversity estimates and absence of heterogeneity, as characterized by SSO typing.

Black People↗
PubMed2001

Meaendering: nature, culture and rivers.

Alongside science we need a parallel capability of exploring meaning so that intangible, uncountable aspects of our relationships with rivers, especially those understood by local communities, can be expressed. Common Ground has offered the concept of Local Distinctiveness and gives examples from England, including recent projects which they have initiated.

Conservation of Natural Resources↗
PubMed1998

Introduction to special section: early Mars.

Ongoing studies of the evolution of the Martian cratered highlands, the nature of the planet's early climate, and the recent announcement of possible evidence of ancient life in the ALH 84001 meteorite have reinvigorated interest in the conditions that prevailed on Mars during its first billion years of geologic history. To address this interest and assess our current understanding of these issues, the Lunar and Planetary Institute hosted a 4-day Conference on Early Mars in Houston in April of 1997. The papers contained in this special section are a product of that meeting. The purpose of the conference was twofold: (1) to consider how impacts, volcanism, and the presence of abundant water affected the physical and chemical environment that existed on Mars 4 Gyr ago, particularly as it related to the nature of the global climate, the origin of the valley networks, the geologic and mineralogic evolution of the surface, the aqueous geochemistry of groundwater, and the existence of local environments that may have been conducive to the development of indigenous life and the preservation of its signature in the geologic record; and (2) to discuss what observations or experiments might he included in future spacecraft missions to test the ideas and expectations arising from purpose 1. While pertinent issues of early atmospheric and solar evolution were also addressed, the primary discussion at the conference focused on the evidence and constraints provided by the geologic records of Earth, the Moon, and Mars and analysis of the SNC meteorites. The papers contained in this special section span the full range of these topics, including the stability of the early atmosphere to erosion by the solar wind, the geologic environment from which the SNC meteorites originated, geomorphic evidence regarding the nature of the early Martian climate and hydrologic cycle, the potential impact of the past and present environment on the preserved signature of ancient life, and a discussion of the capabilities of a lander-based X ray diffraction and fluorescence instrument to assess the potential for past fossilization from the mineralogy of the current local surface environment. The issues raised at the conference, and by the papers included in this special section, will be the focus of ongoing attention as the intensity and scope of Mars exploration increases over the next decade.

Evolution, Planetary↗
PubMed1998

Reduction of radioactive seed embolization to the lung following prostate brachytherapy.

PURPOSE: Ultrasound-guided interstitial implantation of radioactive seeds is a common treatment for early stage prostate cancer. One of the risks associated with this therapy is seed embolization to the lung. This paper reports on the incidence and possible adverse effects of seed migration. METHODS AND MATERIALS: Two hundred ninety consecutive patients were treated with permanent radioactive seed brachytherapy for prostate cancer between January 1 and December 31, 1995. One hundred fifty-four patients were treated with iodine-125 (I-125), and 136 patients were treated with palladium-103 (Pd-103). All but one patient had a routine post implant chest radiograph (CXR), leaving 289 evaluable patients. RESULTS: Twenty radioactive seed pulmonary emboli were identified in 17 patients; 3 patients had two emboli each. The radioactive seed pulmonary embolism rate for the entire group of patients was 5.9%. Acute pulmonary symptoms were not reported by any patient in this series. One hundred forty-six study patients were implanted with free seeds alone (136 Pd-103 and 11 I-125), and 143 were implanted with linked seed embedded in a vicryl suture for the peripheral portions of their implants. The radioactive seed embolization rate by patient was 11% (16/146) versus 0.7% (1/143) for free seed implants and implants utilizing linked seeds, respectively. The difference was statistically significant, p = 0.0002. No patient had detectable morbidity as a consequence of seed emboli. CONCLUSION: The use of linked seeds embedded in vicryl sutures for the peripheral portion of permanent radioactive seed prostate implants significantly reduced the incidence of pulmonary seed embolization in patients treated with the Seattle technique.

Brachytherapy↗
PubMed1998

Genetic evidence for the proto-Austronesian homeland in Asia: mtDNA and nuclear DNA variation in Taiwanese aboriginal tribes.

Previous studies of mtDNA variation in indigenous Taiwanese populations have suggested that they held an ancestral position in the spread of mtDNAs throughout Southeast Asia and Oceania (Melton et al. 1995; Sykes et al. 1995), but the question of an absolute proto-Austronesian homeland remains. To search for Asian roots for indigenous Taiwanese populations, 28 mtDNAs representative of variation in four tribal groups (Ami, Atayal, Bunun, and Paiwan) were sequenced and were compared with each other and with mtDNAs from 25 other populations from Asia and Oceania. In addition, eight polymorphic Alu insertion loci were analyzed, to determine if the pattern of mtDNA variation is concordant with nuclear DNA variation. Tribal groups shared considerable mtDNA sequence identity (P>.90), where gene flow is believed to have been low, arguing for a common source or sources for the tribes. mtDNAs with a 9-bp deletion have considerable mainland-Asian diversity and have spread to Southeast Asia and Oceania through a Taiwanese bottleneck. Only four Taiwanese mtDNA haplotypes without the 9-bp deletion were shared with any other populations, but these shared types were widely dispersed geographically throughout mainland Asia. Phylogenetic and principal-component analyses of Alu loci were concordant with conclusions from the mtDNA analyses; overall, the results suggest that the Taiwanese have temporally deep roots, probably in central or south China, and have been isolated from other Asian populations in recent history.

Alleles↗
PubMed1993

Glutathione-S-transferase pi expression in transitional cell carcinoma of the bladder.

Glutathione-S-transferase pi (GST pi) is a multifunctional protein that acts as an enzyme, involved in the detoxification of drugs and carcinogens. It has been implicated both in drug resistance and malignant transformation of epithelium. Using an indirect immunohistochemical technique, we have evaluated cytoplasmic and nuclear staining in normal urothelium, 23 superficial bladder tumours and 26 invasive tumours. All 26 invasive tumours had been treated with platinum-based chemotherapy. Cytoplasmic staining was seen in normal urothelium and all bladder tumours. Nuclear staining was seen in 1 superficial tumour and in 13 invasive tumours. There was no association between nuclear staining and response to chemotherapy. Nuclear staining was seen in 1 area of dysplasia and in 2 of 3 areas of carcinoma in situ. GST pi expression is not a predictor of response to chemotherapy. Increased intra-nuclear expression of GST pi may be associated with progression of transitional cell carcinoma of the bladder.

Carcinoma, Transitional Cell↗
PubMed1989

Castleman's tumor masquerading as a pancreatic neoplasm.

Castleman's disease, or giant lymph node hyperplasia, occurs most commonly in the mediastinum, with infrequent presentation in the abdominal cavity. We describe a rare occurrence of Castleman's tumor initially seen as a pancreatic mass. The clinical presentation, course, and treatment of this condition are discussed. Clinicians should be aware that giant lymph node hyperplasia may involve the peripancreatic tissues and simulate a pancreatic neoplasm.

Castleman Disease↗
PubMed1988

Anxiety and aspects of health behavior among adolescents in Northern Ireland.

A sample of 238 15- to 16-year-old secondary school students from Northern Ireland answered a questionnaire in their schools about the level of anxiety and some aspects of their health behavior. Analysis of the findings showed that these teenagers had no higher anxiety than a Northern American sample of teenagers. In addition, anxiety was clearly correlated with a variety of health complaints and with use of the health service. The findings are discussed with reference to previous research on adolescent health and on stress in Northern Ireland.

Adolescent↗
PubMed1984

Cervical sagittal spinal canal size in spine injury.

This study investigated the relationship between cervical spine sagittal canal diameter and neurologic injury in cases of spinal fracture-dislocation. A group of 98 patients with such injuries was reviewed; 45 had no neurologic deficits, 39 had incomplete quadriplegia, and 14 had complete quadriplegia. Spinal canal sagittal diameter was measured in all, and large diameter and small canals were defined. Small diameter canals were correlated significantly with neurologic injury, while large diameter canals allowed protection from neurologic injury in cervical fracture dislocation.

Adult↗
PubMed1981

Craniofacial anomalies in the Upper Missouri River over a millennium: archeological and clinical evidence.

Congenital facial clefting occurs more often in Native Americans from the Upper Missouri River Basin (UMRB) than it does in the general population. However, no facial clefts were seen in 3,750 ancient UMRB skeletons. Very few reports concerning defective palate crania are in the literature of paleopathology. Findings regarding craniofacial anomalies in today's native Americans in the UMRB are presented briefly and compared to those in skeletons from this region. There is a marked difference between the frequency of anomalies which occurred in the past and those which are present today. Although the people sampled here were from many cultures and lived during different time periods, encompassing over a millenium, the fundamental denominator was a common geographic location. Reasons for the differences between the past and the present are advanced. It may be possible to estimate the frequency of anomalies which have not been found in archeological specimens but which are present today. By comparing data concerning "occult" congenital anomalies of the past with those of the present, the actual prevalence of past cranio-facial anomalies may be estimated through careful extrapolation.

Bone and Bones↗
PubMed1977

Significance of pneumatosis cystoides intestinalis after jejunoileal bypass.

In 148 radiographs taken two weeks to twenty-seven months postoperatively in a series of 402 jejunoileal bypass patients at the University of Minnesota, twenty-four patients demonstrated roentgen evidence for pneumatosis intestinalis on twenty-eight separate episodes. This primarily involved the right colon. Clinical signs and symptoms were reviewed in association with the roentgen findings. Symptoms of nausea, vomiting, fever, and abdominal stress were noted but were not universal. Six patients had no significant change in abdominal complaints at the time the pneumatosis was seen and seven patients had similar clinical findings without roentgen evidence for pneumatosis. Thus, the radiographic findings of pneumatosis intestinalis do not represent a specific sign for bypass enteritis.

Adult↗