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Biomedical subjects

D Howard

Publications and source records attributed to D Howard.

At least 73 records · Page 4Linked to original sources
PubMed1999

Fistula-in-ano after episiotomy.

BACKGROUND: In the past 2 years, we treated three women with fourth-degree lacerations or episiotomy infections presenting with persistent pain and drainage not responding to standard treatment. CASES: These women were referred for evaluation 5 weeks, 3.5 months, and 2 years postpartum. After diagnosing fistula-in-ano, we treated them with fistulotomy and curettage, which resolved the problem. CONCLUSION: When a patient presents with pain or drainage at her episiotomy site, fistula-in-ano should be considered.

Adult↗
PubMed1999

Complement depletion does not reduce brain injury in a rabbit model of thromboembolic stroke.

The contribution of the complement system to cerebral ischemic and ischemia/reperfusion injury was examined in a rabbit model of thromboembolic stroke by delivery of an autologous clot embolus to the intracranial circulation via the internal carotid artery. A two-by-two factorial design was employed to study the impact of complement depletion via pretreatment with cobra venom factor (CVF, 100 U/kg i.v.) in the setting of permanent (without tissue plasminogen activator; t-PA) and transient (with t-PA) cerebral ischemia. Thirty-two New Zealand white rabbits were assigned to one of four groups (n=8, each group): control without t-PA, control with t-PA, CVF without t-PA and CVF with t-PA. In the complement intact animals, t-PA administration resulted in an approximate 30% reduction in infarct size when compared to the group not receiving t-PA (20.4+/-6.6% of hemisphere area vs. 30.1+/-7.2%; mean+/-SEM). However, infarct sizes in the complement depleted rabbits, with (30.7+/-8.2%) or without (30.2+/-7.9%) t-PA, were no different from the control group receiving no therapy. Similarly, no difference in regional cerebral blood flow or final intracranial pressure values was noted between any of the four groups. Complement activation does not appear to be a primary contributor to brain injury in acute thromboembolic stroke.

Animals↗
PubMed1999

Dynamic contrast-enhanced MRI of Implanted VX2 tumors in rabbit muscle: comparison of Gd-DTPA and NMS60.

We studied the dynamics of injected contrast enhancement in implanted VX2 tumors in rabbit thigh muscle. We compared two contrast agents Gd-DTPA and NMS60, a novel gadolinium containing trimer of molecular weight 2.1 kd. T1-weighted spin echo images were acquired preinjection and at 5-60 min after i.v. injection of 0.1 mmol/kg of agent. Dynamic T1-weighted SPGR images (1.9 s/image) were acquired during the bolus injection. Male NZW rabbits (n = 13) were implanted with approximately 2 x 10(6) VX2 tumor cells and grew tumors of 28+/-27 mL over 12 to 21 days. NMS60 showed significantly greater peak enhancement in muscle, tumor rim, and core compared to DTPA in both T1-weighted and SPGR images. NMS60 also showed delayed peak enhancement in the dynamic scans (compared to Gd-DTPA) and significantly reduced leakage rate constant into the extravascular space for tumor rim (K21 = 5.1 min(-1) vs. 11.5 min(-1) based on a 2 compartment kinetic model). The intermediate weight contrast agent NMS60 offers greater tumor enhancement than Gd-DTPA and may offer improved regional differentiation on the basis of vascular permeability in tumors.

Animals↗
PubMed1999

Dimensional change in muscle as a control signal for powered upper limb prostheses: a pilot study.

The vast majority of externally powered prostheses are controlled from the myoelectric signal, measured at the skin surface using socket-located electrodes. This signal has been well researched and sophisticated signal processing methods developed. Nevertheless, the inherent properties of the signal, such as its broad bandwidth and low voltage amplitude, make its use less than straightforward in the control of low frequency activity such as powered prosthetic hand movement. This paper reports on a pilot study of an alternative, a signal derived from dimensional change in muscle. A new socket-located sensor was designed to measure dimensional change in muscle, the linearised output of which is termed the myokinemetric (MK) signal. This was used in a series of tasks aimed at investigating the potential for its use in upper-limb prosthesis control. Six amputee subjects were tested, of whom one was a regular user of the myoelectric hand, one had some experience, and four had little or no previous experience of controlling devices using their residual limb. Data is presented on the problems of shift in signal range with time and socket donning and doffing and on the ability of subjects to control the amplitude of the signal. The results show that subjects were able to control the magnitude of the MK signal to a significant degree, with typical errors averaging 0.1-0.3 mm, around 10% of the signal range. The principal problem encountered was the shift in signal with time and socket donning and doffing.

Adult↗
PubMed1999

Juvenile angiofibroma: the lessons of 20 years of modern imaging.

Seventy-two patients with juvenile angiofibroma have been investigated by computerized tomography (CT) and/or magnetic resonance imaging (MRI) over a period of 20 years. The evidence from these studies indicates that angiofibroma takes origin in the pterygo-palatine fossa at the aperture of the pterygoid (vidian) canal. An important extension of the tumour is posteriorly along the pterygoid canal with invasion of the cancellous bone of the pterygoid base, and greater wing of the sphenoid (60 per cent of patients). Distinctive features of angiofibroma are the high recurrence rate, and the rapidity with which many tumours recur. It is postulated that the principal determinant of recurrence is a high tumour growth rate at the time of surgery coupled with incomplete surgical excision. The inability to remove the tumour in toto is principally due to deep invasion of the sphenoid, as described above. In this series 93 per cent of recurrences occurred with this type of tumour extension. A contributory cause in these patients is the use of pre-operative embolization. The treatment implications of these findings are examined.

Adolescent↗
PubMed1998

Distress symptoms among urban African American children and adolescents: a psychometric evaluation of the Checklist of Children's Distress Symptoms.

OBJECTIVES: To explore the factor structure of the Checklist of Children's Distress Symptoms (CCDS); to examine whether there is a higher-order single construct underlying the CCDS measure; and, to assess the association between children's distress symptoms, as reflected by the CCDS factors, and children's self-reported exposure to community violence (both victimization and witness events). DESIGNS: Community-based cross-sectional survey. SETTINGS: Ten public housing developments in an eastern metropolis. PARTICIPANTS: A total of 349 low-income urban African American children and adolescents (198 males; 151 females), 9 through 15 years of age. MEASURES: Children's distress symptoms, exposure to community violence, and selected demographic information including parental education, parental employment status, perceived health status, and school performance. ANALYSIS: Exploratory factor analysis was performed to determine the factorial structure of the CCDS measure. Second-order confirmatory factor analysis was performed to determine if there is a higher-order single underlying construct among CCDS factors. Pearson correlation coefficients were computed to assess the relationship between exposure to violence and CCDS factors. MAJOR FINDINGS: The exploratory factor analysis yielded a 6-factor solution for the CCDS measure with satisfactory internal consistency. The confirmatory factor model with a single second-order construct yielded a good fit to the data. In general, youth who experienced violent victimization or witnessed violent events reported higher levels of distress symptoms than those who did not. Distress symptoms labeled as "intrusive thoughts," "distraction," and "lack of belongingness" were most frequently associated with exposure to violence. Distress symptoms did not differ on the basis of sex or age. CONCLUSIONS: The CCDS has utility as a measure of distress symptoms among urban African American children and adolescents. Whereas analysis provided support for a single higher-order construct, using the proposed 6-factor structure should enhance our understanding of the psychological impact of exposure to violence on youth and contribute to more effective intervention efforts.

Adolescent↗
PubMed1998

Medical examiner cases associated with previously undiagnosed diabetes mellitus, North Carolina, 1994.

BACKGROUND: Approximately half of the 16 million Americans with diabetes mellitus (DM) are unaware they have the disease; the epidemiology of death from previously undiagnosed DM is unclear. We report medical examiner (ME) cases of death from DM in North Carolina in 1994 to determine the number and characteristics of these cases. METHODS: Deaths from DM ICD-9 were identified and reviewed. RESULTS: Of the 42 cases ascertained from ME records, 6 had previously undiagnosed DM, 5 had diabetes ketoacidosis, and 1 had nonketotic hyperosmolar hyperglycemia. Mean patient age at death for all cases was 42 years (range, 35 years to 57 years). Four patients felt bad at least 24 hours before death, indicating that they are not technically "sudden deaths." CONCLUSIONS: We provide a limited epidemiologic perspective of the phenomenon of death from undiagnosed DM. We suggest further investigation of mortality from previously undiagnosed diabetes.

Adolescent↗
PubMed1998

Biased T-cell antigen receptor repertoire in Lyme arthritis.

A common concern with many autoimmune diseases of unknown etiology is the extent to which tissue T-lymphocyte infiltrates, versus a nonspecific infiltrate, reflect a response to the causative agent. Lyme arthritis can histologically resemble rheumatoid synovitis, particularly the prominent infiltration by T lymphocytes. This has raised speculation about whether Lyme synovitis represents an ongoing response to the causative spirochete, Borrelia burgdorferi, or rather a self-perpetuating autoimmune reaction. In an effort to answer this question, the present study examined the repertoire of infiltrating T cells in synovial fluid from nine Lyme arthritis patients, before and after stimulation with B. burgdorferi. Using a highly sensitive and consistent quantitative PCR technique, a comparison of the T-cell antigen receptor (TCR) beta-chain variable (Vbeta) repertoires of the peripheral blood and synovial fluid showed a statistically significant increase in expression of Vbeta2 and Vbeta6 in the latter. This is remarkably similar to our previous findings in studies of rheumatoid arthritis and to other reports on psoriatic skin lesions. However, stimulation of synovial fluid T cells with B. burgdorferi provoked active proliferation but not a statistically significant increase in expression of any TCR Vbeta, including Vbeta2 and Vbeta6. Collectively, the findings suggest that the skewing of the TCR repertoire of fresh synovial fluid in Lyme arthritis may represent more a synovium-tropic or nonspecific inflammatory response, similar to that occurring in rheumatoid arthritis or psoriasis, rather than a specific Borrelia reaction.

Adolescent↗
PubMed1998

A functional neuroimaging description of two deep dyslexic patients.

Deep dyslexia is a striking reading disorder that results from left-hemisphere brain damage and is characterized by semantic errors in reading single words aloud (e.g., reading 'spirit' as 'whisky'). Two types of explanation for this syndrome have been advanced. One is that deep dyslexia results from a residual left-hemisphere reading system that has lost the ability to pronounce a printed word without reference to meaning. The second is that deep dyslexia reflects right-hemisphere word processing. Although previous attempts to adjudicate between these hypotheses have been inconclusive, the controversy can now be addressed by mapping functional anatomy. In this study, we demonstrate that reading by two deep dyslexic patients (CJ and JG) involves normal or enhanced activity in spared left-hemisphere regions associated with naming (Broca's area and the left posterior inferior temporal cortex) and with the meanings of words (the left posterior temporo-parietal cortex and the left anterior temporal cortex). In the right-hemisphere homologues of these regions, there was inconsistent activation within the normal group and between the deep dyslexic patients. One (CJ) showed enhanced activity (relative to the normals) in the right anterior inferior temporal cortex, the other (JG) in the right Broca's area, and both in the right frontal operculum. Although these differential right-hemisphere activations may have influenced the reading behavior of the patients, their activation patterns primarily reflect semantic and phonological systems in spared regions of the left hemisphere. These results preclude an explanation of deep dyslexia in terms of purely right-hemisphere word processing.

Brain Mapping↗
PubMed1998

Heart rate variability reflects severity of COPD in PiZ alpha1-antitrypsin deficiency.

BACKGROUND: Analysis of heart rate variability (HRV) is a powerful method of assessing severity of conditions affecting the autonomic nervous system. STUDY OBJECTIVE: To determine if HRV is decreased and if HRV reflects severity in COPD. DESIGN: Prospective determination of HRV from 24-h outpatient Holter recordings. PATIENTS: Eighteen individuals with PiZ alpha1-antitrypsin deficiency: 13 with COPD and 5 with normal FEV1. HRV was also determined in 18 matched normal control subjects. Approximately 3 years after the initial recording, all COPD subjects were contacted to determine current status. MEASUREMENTS: Indexes of heart rate (HR) and HRV were compared for groups of patients with and without COPD and their control subjects. RESULTS: Mean and minimum HRs were higher in COPD patients. Virtually all indexes of HRV were significantly decreased in COPD patients. No differences were found in HR or HRV between PiZ individuals with normal FEV1 and their age-and gender-matched control subjects. Patients who had a change in status (ie, death, lung transplant, listed for transplant) had significantly higher daytime HRs, lower values for HRV indexes reflecting mixed sympathetic and parasympathetic modulation of HR, and reduced daytime high-frequency spectral power, an index of cardiac vagal modulation. Significant correlations (r=0.48 to 0.88) were found between FEV1 and these and other indexes of HRV. Most other indexes of HRV also tended to be lower for the group whose status had changed. CONCLUSION: PiZ alpha1-antitrypsin deficiency COPD is associated with abnormal cardiac autonomic modulation. Indexes of HRV appear to reflect severity and may have prognostic value in COPD patients.

Adult↗
PubMed1998

Localization of bronchial intraepithelial neoplastic lesions by fluorescence bronchoscopy.

BACKGROUND: In the treatment of lung cancer, the best outcome is achieved when the lesion is discovered in the intraepithelial (preinvasive) stage. However, intraepithelial neoplastic lesions are difficult to localize by conventional white-light bronchoscopy (WLB). OBJECTIVE: To determine if autofluorescence bronchoscopy, when used as an adjunct to WLB, could improve the bronchoscopist's ability to locate and remove biopsy specimens from areas suspicious of intraepithelial neoplasia as compared with WLB alone. METHOD: A multicenter clinical trial was conducted in seven institutions in the United States and Canada. WLB followed by fluorescence examination with the light-induced fluorescence endoscopy (LIFE) device was performed in 173 subjects known or suspected to have lung cancer. Biopsy specimens were taken from all areas suspicious of moderate dysplasia or worse on WLB and/or LIFE examination. In addition, random biopsy specimens were also taken from other parts of the bronchial tree. RESULTS: The relative sensitivity of WLB + LIFE vs WLB alone was 6.3 for intraepithelial neoplastic lesions and 2.71 when invasive carcinomas were also included. The positive predictive value was 0.33 and 0.39 and the negative predictive value was 0.89 and 0.83, respectively, for WLB+LIFE and WLB alone. CONCLUSION: Autofluorescence bronchoscopy, when used as an adjunct to standard WLB, enhances the bronchoscopist's ability to localize small neoplastic lesions, especially intraepithelial lesions that may have significant implication in the management of lung cancer in the future.

Adult↗
PubMed1998

Treating word-finding difficulties--beyond picture naming.

This paper presents some preliminary findings from research into the phonological treatment of word-finding difficulties in aphasia focusing on two areas of investigation. Firstly we report on the effects of giving a choice of phonological cues on word-finding. Secondly we describe our findings concerning the reliability of a measure of real-life interaction.

Aphasia↗
PubMed1997

Fractionating the articulatory loop: dissociations and associations in phonological recoding in aphasia.

This paper uses neuropsychological data to differentiate between three models of verbal short-term memory (Baddeley, 1983, 1986; Besner, 1987; Monsell, 1987). The focus is on three tasks: homophone judgments, rhyme judgments and pseudohomophone detection. When lesioned each model predicts characteristic patterns of impairment across these tasks. Thirteen span impaired aphasic subjects were assessed on all three tasks. The patterns of performance unequivocally supported the model proposed by Monsell (1987) which distinguishes input and output phonological buffers. Implications for further research are discussed.

Adult↗
PubMed1997

In vitro study of the mechanical effects of shock-wave lithotripsy.

Impulsive stress in repeated shock waves administered during extracorporeal shock-wave lithotripsy (ESWL) causes injury to kidney tissue. In a study of the mechanical input of ESWL, the effects of focused shock waves on thin planar polymeric membranes immersed in a variety of tissue-mimicking fluids have been examined. A direct mechanism of failure by shock compression and an indirect mechanism by bubble collapse have been observed. Thin membranes are easily damaged by bubble collapse. After propagating through cavitation-free acoustically heterogeneous media (liquids mixed with hollow glass spheres, and tissue) shock waves cause membranes to fail in fatigue by a shearing mechanism. As is characteristic of dynamic fatigue, the failure stress increases with strain rate, determined by the amplitude and rise time of the attenuated shock wave. Shocks with large amplitude and short rise time (i.e., in uniform media) cause no damage. Thus the inhomogeneity of tissue is likely to contribute to injury in ESWL. A definition of dose is proposed which yields a criterion for damage based on measurable shock wave properties.

Castor Oil↗