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Biomedical subjects

N Clark

Publications and source records attributed to N Clark.

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

Subunit principles in midface fractures: the importance of sagittal buttresses, soft-tissue reductions, and sequencing treatment of segmental fractures.

The patterns of midface fractures were related to postoperative computed tomography scans and clinical results to assess the value of ordering fracture assembly in success of treatment methods. A total of 550 midface fractures were studied for their midface components and the presence of fractures in the adjacent frontal bone or mandible. Preoperative and postoperative computed tomography scans were analyzed to generate recommendations regarding exposure and postoperative stability related to fracture pattern and treatment sequence, both within the midface alone and when combined with frontal bone and mandibular fractures. Large segment (Le Fort I, II, and III) fractures were seen in 68 patients (12 percent); more comminuted midface fracture combinations were seen in 93 patients (17 percent). Midface and mandibular fractures were seen in 166 patients (30 percent). Midface, mandible, and nasoethmoid fractures were seen in 38 patients (7 percent). Frontal bone and midface fractures were seen in 131 patients (24 percent). Split-palate fractures accompanied 8 percent of midface fractures. Frontal bone, midface, and mandibular fractures were seen in 54 patients (10 percent). The midface, because of weak bone structure and comminuted fracture pattern, must therefore be considered a dependent, less stable structure. Its injuries more commonly occur with fractures of the frontal bone or mandible (two-thirds of cases) and, more often than not (>60 percent), are comminuted. Comminuted and pan-facial (multiple area) fractures deserve individualized consideration regarding the length of intermaxillary immobilization. Examples of common errors are described from this patient experience.

Facial Asymmetry↗
PubMed1998

Chondrosarcoma of the aorta: a rare source of bowel and lower extremity emboli.

Malignant aortic tumors occur infrequently. At least 70 cases of primary aortic malignancies have been reported in the literature. Within this group, chondrosarcoma is exceedingly rare, with only 1 case having been reported. An aortic chondrosarcoma developed in our patient and embolized to the small bowel and lower extremities. Although initially thought to arise from the abdominal aorta, this tumor, in fact, originated from the thoracic aorta. This case illustrates the need for complete aortic imaging when unexplained recurrent embolization occurs. In general, the survival rates with chondrosarcoma are diminished, but this patient survived 69 months after he was initially seen.

Aged↗
PubMed1998

Abdominal aortic aneurysm in a young child: a 25-year follow-up study.

Although abdominal aortic aneurysm (AAA) is a common problem in elderly patients, AAA is rare in children. Despite its rarity, early diagnosis is imperative to prevent limb-threatening or fatal complications. The treatment may be complicated, because it must allow for the growth of the child. A saccular AAA in an 11-year-old boy, complicated by three repeated embolizations to the lower extremities and treated by aneurysmorrhaphy 25 years ago, was studied. In addition, the long-term function of a vein interposition graft in the common femoral artery was identified.

Aortic Aneurysm, Abdominal↗
PubMed1998

Absconding: a literature review.

Incidents of absconding from inpatient care are high-risk events which have been linked to serious harm to self and others. This paper brings together for the first time findings from a disparate body of research literature spanning many years. Varied definitions of absconding and methods of calculating the rates of absconding make comparisons between studies difficult. Nevertheless, it is clear that absconders are more often young, male, from disadvantaged groups, and suffering from schizophrenia, compared to admissions generally. Roughly half of the abscondings take place while the patient is temporarily off the ward with permission, the remainder of absconding patients use an assortment of means to make their escape. A large variety of reasons for absconding have been elicited from patients or advanced as possibilities by researchers. Only six evaluative studies of interventions impacting upon absconding have been reported in the literature, but no firm conclusions can be drawn from them.

Female↗
PubMed1998

New reference reagent for the quality assurance of anti-D antibody detection.

A UK BTS-NIBSC freeze-dried anti-D preparation has been prepared and used to monitor the performance of routine antibody detection tests and of the test operators. With the day-to-day use of this preparation, adverse changes in test performance and in test operator may be detected and appropriate action taken before the effect becomes significant. Two dilutions of this preparation have been defined, one which should be detected unequivocally in every test; the other, more dilute, may not be detected in every test but is used to monitor changes in performance. Experience with the use of this preparation is reported from three test centres undertaking routine antibody detection tests. By monitoring results over a series of working days, significant differences were noted in operator performance within one test centre, as was a reduced sensitivity of a given test system within one test centre compared with the same system in the other test centres. These differences were detected only by monitoring the results obtained with this preparation.

Coombs Test↗
PubMed1998

Palatal fractures: classification, patterns, and treatment with rigid internal fixation.

A classification of palatal fracture types is developed from patterns observed on CT scans, and success with open reduction techniques is correlated with fracture pattern. The six palatal fracture types are as follows: I, anterior and posterolateral alveolar; II, sagittal; III, parasagittal; IV, para-alveolar; V, complex; and VI, transverse. Associated fractures were LeFort I (100 percent), LeFort II and III (55 percent), mandible (48 percent), and dental (55 percent). Large segment, sagittally oriented palatal fractures could be stabilized with rigid internal fixation. Complete rigid fixation of the palate consists of (1) roof of mouth, (2) pyriform or alveolar, and (3) four LeFort I buttress stabilization. Comminuted palatal fractures were managed by standard LeFort I and alveolar buttress fixation, palatal splinting, and intermaxillary, fixation. If complete rigid fixation was employed in the palate in type II, III, and IV fractures, a palatal splint was avoided in 60 percent of these cases. Rigid internal fixation is therefore concluded to facilitate the treatment of certain types of palatal fractures by reduced length of intermaxillary fixation and avoidance of palatal splinting.

Alveolar Process↗
PubMed1998

Nutrition support programs for young adult athletes.

After graduating from college and entering the work force, young adult athletes often struggle with the task of fueling themselves optimally for top performance and weight control. The stresses and time constraints of work, family, and social responsibilities often result in eating fast foods on the run. These young adults can benefit from nutrition education programs in the worksite, at health clubs, in the community, and via the media. Dietitians who specialize in sport nutrition have particular appeal to these athletes, who are struggling to each well, exercise well, and stay lean yet put little time or effort into their food program. This article includes two case studies of young adults and the dietary recommendations that taught them how to make wise food choices, fuel themselves well for high energy, and control their weight.

Adult↗
PubMed1997

The edentulous Le Fort fracture.

A retrospective review of 328 Le Fort fractures has identified 20 (6.1%) of these fractures as edentulous. A review of treatment of the patients was conducted. Conservative (nonsurgical treatment methods) and classic open reductions produce aesthetic and functional results that lead to posterior and oblique positioning of the maxillary occlusal segment in comminuted fractures. Attention to positioning the maxilla by relating it to the mandible through maxillomandibular fixation minimized these deformities. Establishing maxillary-mandibular relationships in edentulous fractures, therefore, seems to have the same importance as establishing occlusion in dentulous patients as an important initial step in the treatment of comminuted Le Fort fractures.

Adult↗
PubMed1997

Computer simulated cost effectiveness of care management strategies on reduction of long-term sequelae in patients with non-insulin dependent diabetes mellitus.

Systems dynamics and computer "microworlds" offer a window on the long-term benefit of investing in aggressive care management for patients with non-insulin dependent diabetes mellitus. This article describes how clinicians, planners, payment specialists, and patients collaborated to make the business case for aggressive management of this disease.

Blood Glucose↗
PubMed1997

Detection of vancomycin-resistant enterococci in fecal samples by PCR.

Surveillance cultures for vancomycin-resistant enterococci (VRE) are time-consuming and expensive for the laboratory to perform. Therefore, we investigated the use of PCR as an alternative method of detecting and identifying VRE directly in fecal samples. PCR primers directed to vanA, vanB, vanC1, vanC2, and enterococcal ligase genes were used to detect and identify VRE in fecal material obtained by rectal or perirectal swabbing. Although PCR-inhibitory substances were present in DNA prepared directly from the swabs, the inhibitory substances could be reduced by processing the nucleic acid with two commercially available DNA preparation columns. Fecal material from 333 swabs was cultured on several selective agar media before and after broth enrichment. DNA was extracted from the fecal material and was analyzed by PCR. By using all four primer sets, only 59 (67.8%) of the samples were positive for vanA. However, after retesting the negative samples with only the vanA primer set, 77 (88.5%) of 87 specimens that were culture positive for Enterococcus faecium containing vanA were positive by PCR. One specimen was PCR positive for the vanA gene but culture negative for enterococci. The specificity of the vanA assay was 99.6%. PCR analysis of enrichment broth samples with all four primers sets after 15 to 18 h of incubation detected 74 (85.1%) of the 87 culture-positive specimens. The specificity of the vanA assay after the enrichment step was 100%. No vanB-containing enterococci were recovered by culture. Since 16 samples can be tested by PCR in 4 h (including electrophoresis), identification of VRE is possible within 8 h of specimen submission at a cost of approximately $10.12/assay. Thus, PCR may be a cost-effective alternative to culture for surveillance of VRE in some hospitals.

Anti-Bacterial Agents↗
PubMed1997

Structure-function studies of the human immunodeficiency virus type 1 matrix protein, p17.

The human immunodeficiency virus type 1 (HIV-1) matrix protein, p17, plays important roles in both the early and late stages of the viral life cycle. Using our previously determined solution structure of p17, we have undertaken a rational mutagenesis program aimed at mapping structure-function relationships within the molecule. Amino acids hypothesized to be important for p17 function were mutated and examined for effect in an infectious proviral clone of HIV-1. In parallel, we analyzed by nuclear magnetic resonance spectroscopy the structure of recombinant p17 protein containing such substitutions. These analyses identified three classes of mutants that were defective in viral replication: (i) proteins containing substitutions at internal residues that grossly distorted the structure of recombinant p17 and prevented viral particle formation, (ii) mutations at putative p17 trimer interfaces that allowed correct folding of recombinant protein but produced virus that was defective in particle assembly, and (iii) substitution of basic residues in helix A that caused some relocation of virus assembly to intracellular locations and produced normally budded virions that were completely noninfectious.

Amino Acid Sequence↗
PubMed1997

Improving care for minority children with asthma: professional education in public health clinics.

OBJECTIVE: Recent studies have shown that lack of continuing primary care for asthma is associated with increased levels of morbidity in low-income minority children. Although effective preventive therapy is available, many African-American and Latino children receive episodic treatment for asthma that does not follow current guidelines for care. To see if access, continuity, and quality of care could be improved in pediatric clinics serving low-income children in New York City, we trained staff in New York City Bureau of Child Health clinics to provide continuing, preventive care for asthma. METHODS: We evaluated the impact of the intervention over a 2-year period in a controlled study of 22 clinics. Training for intervention clinic staff was based on National Asthma Education and Prevention Program guidelines for the diagnosis and management of asthma, and included screening to identify new cases and health education to improve family management. The intervention included strong administrative support by the Bureau of Child Health to promote staff behavior change. We hypothesized that after the intervention, clinics that received the intervention would, compared with control clinics, have increased numbers of children with asthma receiving continuing care in the clinics and increased staff use of new pharmacologic and educational treatment methods. RESULTS: In both the first and second follow-up years, the intervention clinics had greater positive changes than control clinics on measures of access, continuity, and quality of care. For second year follow-up data these include: for access, greater rate of new asthma patients (40/1000 vs 16/1000; P < .01); for continuity, greater percentage of asthma patients returning for treatment 2 years in a row (42% vs 12%; P < .001) and greater annual frequency of scheduled visits for asthma per patient (1.85 vs .88; P < .001); and for quality, greater percentage of patients receiving inhaled beta agonists (52% vs 15%; P < .001) and inhaled antiinflammatory drugs (25% vs 2%; P < .001), and greater percentages of parents who reported receiving patient education on 12 topics from Bureau of Child Health physicians (71% vs 58%; P < .01) and nurses (61% vs 44%; P < .05). CONCLUSION: We conclude that the intervention substantially increased the Bureau of Child Health staff's ability to identify children with asthma, involve them in continuing care, and provide them with state-of-the-art care for asthma.

Black or African American↗
PubMed1997

Evaluation of magnetic foil and PPT Insoles in the treatment of heel pain.

The effect of a magnetic foil placed in the PPT/Rx Firm Molded Insole on the relief of heel pain was determined using the foot function index. Nineteen patients wore the PPT/Rx Firm Molded Insoles with the magnetic foil for 4 weeks and 15 patients wore the same PPT/Rx Firm Molded Insole with no magnetic foil for the same time. Approximately 60% of patients in both groups reported improvement. There was also no significant difference in the improvement between the magnetic foil group and the PPT/Rx Firm Molded Insole group in their scores on the post-treatment foot function index. These results suggest that the PPT/Rx Firm Molded Insole alone was effective in treating heel pain after only 4 weeks. The magnetic foil offered no advantage over the plain insole.

Adolescent↗
PubMed1997

Comparison of Viscoped and PORON for painful submetatarsal hyperkeratotic lesions.

A clinical study was performed to evaluate the efficacy of the Viscoped Insole as compared with an 1/8-inch PORON medical materials insole in the treatment of lesser submetatarsal hyperkeratotic callosities. Thirty-five patients, ranging in age from 23 through 61 years (average 42 years) were randomly divided into three groups. All three groups initially had debridement of their submetatarsal callosities. In addition to the debridement, the first group (16 patients) wore a Viscoped Insole for 4 weeks. The patients in the second group wore a PORON insole for 4 weeks. The third group did not receive an insole after their debridement and served as the control. There was a significant improvement in the Viscoped group and the PORON group versus the control group (x2 = 40; p < 0.01) as measured by the foot function index. Insole therapy combined with debridement for submetatarsal hyperkeratoses is more effective than debridement alone.

Callosities↗
PubMed1996

Tissue inhibitor of metalloproteinase-1 messenger RNA expression is enhanced relative to interstitial collagenase messenger RNA in experimental liver injury and fibrosis.

Liver fibrosis results from a relative imbalance between synthesis and degradation of matrix proteins. We have previously described release of the protein collagenase inhibitor, tissue inhibitor of metalloproteinase-1 (TIMP-1), by culture-activated human hepatic stellate cells (HSCs). In this study, we have investigated the relative expression of TIMP-1 and interstitial collagenase in culture-activated rat HSCs and rat models of liver injury and fibrosis. The complementary DNA (cDNA) for rat TIMP-1 was obtained by homology polymerase chain reaction (PCR) and sequenced. By Northern analysis using this probe, TIMP-1 messenger RNA (mRNA) expression was up-regulated with HSC activation by culture on plastic as defined by cellular expression of procollagen-1. Interstitial collagenase mRNA was expressed in early 1. Interstitial collagenase mRNA was expressed in early culture (<4 days) but became undetectable in more activated cells (7-21 days). By activity assay of serum-free cell-conditioned media, TIMP-1 was found to be released in increasingly concentrations with duration of culture on plastic. Expression of TIMP-1 interstitial collagenase, and procollagen-1 mRNAs were studied in rat models of biliary and parenchymal injury (bile duct ligation and CC14 administration) by ribonuclease protein assay. TIMP-1 mRNA expression was increased at 6, 24 hours, and 3 days after bile duct ligation and was also shown to rise in acute CC14 liver injury and remain elevated as the liver became fibrotic. TIMP-1 expression preceded procollagen-1 expression in both models. In contrasts, interstitial collagenase mRNA levels remained similar to control values throughout both models of liver injury. Total cellular RNA from hepatocytes, HSCs, and kupffer cells freshly isolated from livers after acute CC14 injury was subjected to Northern analysis. TIMP-1 transcripts were observed in nonparenchymal cells only. We suggest that increased expression of TIMP-1 relative to interstitial collagenase by HSCs may promote progression of liver fibrosis in these rat models by preventing degradation of secreted collagens.

Amino Acid Sequence↗
PubMed1996

High-energy ballistic and avulsive facial injuries: classification, patterns, and an algorithm for primary reconstruction.

A 17-year experience from 1977 to 1993 with gunshot, shotgun, and high-energy avulsive facial injuries emphasizes the superiority and safety of "ballistic wound" surgical management: (1) immediate stabilization in anatomic position of existing bone, (2) primary closure of existing soft tissue, (3) periodic "second look" serial debridement procedures, and (4) definitive early reconstruction of soft-tissue and bony defects. The series contains 250 gunshot wounds, 53 close-range shotgun wounds, and 15 high-energy avulsive facial injuries. Four general patterns of involvement are noted for both gunshot and shotgun wounds and three for avulsive facial injuries. The treatment algorithm begins with identifying zones of injury and loss for both soft and hard tissue. Gunshot wounds are best classified by the location of the exit wound; shotgun and avulsive facial wounds are classified according to the zone of soft-tissue and bone loss. Treatment, prognosis, and complications vary according to four patterns of gunshot wounds and four patterns of shotgun wounds. Avulsive wounds have not been recommended previously for ballistic wound surgical management. The appropriate management of high-energy avulsive and ballistic facial injuries is best approached by an aggressive treatment program emphasizing initial primary repair of existing tissue, serial conservative debridement, and early definitive reconstruction.

Adult↗