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Biomedical subjects

D Howard

Publications and source records attributed to D Howard.

At least 55 records · Page 3Linked to original sources
PubMed2000

Differences in perineal lacerations in black and white primiparas.

OBJECTIVE: To test the null hypothesis that there are no differences in incidence of perineal and vaginal lacerations in primiparous black and white women. METHODS: We reviewed University of Michigan Hospital delivery records, from July 1996 to December 1998, of black and white women 18 years and older and at least 35 weeks' gestation who had their first vaginal delivery. Birth weight, episiotomy, gestational age, laceration, length of second stage, oxytocin use, epidural use, and operative vaginal delivery were analyzed by univariable and multivariable tests. RESULTS: We analyzed 176 black women (mean age +/- standard deviation 23.7 +/- 4.7 years; range 18-41 years) and 1633 white women (27.8 +/- 5.4 years; 18-49 years; P <.001). Black women were less likely to have second, third, or fourth degree lacerations (43% compared with 59%; P <.001). The mean length of second stage of labor was shorter in the black women (73 +/- 69 minutes; range 3-494 minutes compared with 106 +/- 78 minutes; range 2-642 minutes; P <.001). Infants of black women weighed less (3292 +/- 490 g; 1990-5190 g compared with 3429 +/- 470 g; 1860-4950 g; P <.001). Multivariable analysis showed that black women were twice as likely to deliver with intact perineums than white women (P <.001). CONCLUSION: Black primiparas were less likely to deliver with second-degree or greater lacerations and more likely to deliver with their perineums intact.

Adolescent↗
PubMed2000

Differential effects of cough, valsalva, and continence status on vesical neck movement.

OBJECTIVE: We tested the null hypothesis that vesical neck descent is the same during a cough and during a Valsalva maneuver. We also tested the secondary null hypothesis that differences in vesical neck mobility would be independent of parity and continence status. METHODS: Three groups were included: 17 nulliparous continent (31.3 +/- 5.6; range 22-42 years), 18 primiparous continent (30.4 +/- 4.3; 24-43), and 23 primiparous stress-incontinent (31.9 +/- 3.9; 25-38) women. Measures of vesical neck position at rest and during displacement were obtained by ultrasound. Abdominal pressures were recorded simultaneously using an intravaginal microtransducer catheter. To control for differing abdominal pressures, the stiffness of the vesical neck support was calculated by dividing the pressure exerted during a particular effort by the urethral descent during that effort. RESULTS: The primiparous stress-incontinent women displayed similar vesical neck mobility during a cough effort and during a Valsalva maneuver (13.8 mm compared with 14.8 mm; P =.49). The nulliparous continent women (8.2 mm compared with 12.4 mm; P =. 001) and the primiparous continent women (9.9 mm compared with 14.5 mm; P =.002) displayed less mobility during a cough than during a Valsalva maneuver despite greater abdominal pressure during cough. The nulliparas displayed greater pelvic floor stiffness during a cough compared with the continent and incontinent primiparas (22.7, 15.5, 12.2 cm H(2)O/mm, respectively; P =.001). CONCLUSION: There are quantifiable differences in vesical neck mobility during a cough and Valsalva maneuver in continent women. This difference is lost in the primiparous stress-incontinent women.

Adult↗
PubMed2000

On the differences between conventional and auditory spectrograms of English consonants.

A new tool for speech analysis is presented, operating in real-time and incorporating the analysing power of a contemporary auditory model to produce the familiar display of the speech spectrograph. This "auditory spectrograph" is used to analyse English consonant sounds and the results are compared with conventional wide and narrow band spectrograms. The auditory analyses are found to attach more visual weight to the acoustic cues associated with speech production and perception, and features that are either difficult or impossible to distinguish on conventional spectrograms are clarified.

Female↗
PubMed2000

Prospective allometric scaling: does the emperor have clothes?

We are not suggesting that an allometric relationship between pharmacokinetic parameters in animals and humans does not exist; we believe that it does. We are suggesting that using prospective AS to select doses in an FTIM study may lead to a false sense of security given the large publication bias in the literature. There are a number of unrecognized pitfalls to this approach, including (1) prediction intervals so wide as to be of limited use, (2) prediction error is often no better than arbitrarily chosen constants, and (3) it is not possible to determine which drugs will fail a priori. We encourage journals to publish studies in which prospective AS has failed so as scientists we may begin to see what makes these compounds different, with a goal toward better prediction of human pharmacokinetics.

Animals↗
PubMed2000

Fungal rhinosinusitis.

Fungal infections in both their invasive and non-invasive forms can prove difficult to diagnose. The often characteristic appearances on imaging are of great assistance. CT is the primary imaging modality and is probably more accurate than MRI in diagnostic specificity and determining the extent of bone erosion. However this may require a modified scanning technique to adequately demonstrate the typical soft tissue density variations of fungi. MRI should be used to supplement CT when intra-cranial or intra-orbital extension is suspected.

Humans↗
PubMed2000

Optimum imaging for inverted papilloma.

Inverted papilloma is the most common benign tumour of the nose and paranasal sinuses, and usually arises in the lateral wall of the nasal cavity and the middle meatus. The diagnosis is suggested on computed tomography (CT) when there is a mass continuous from the middle meatus into the adjacent maxillary antrum, through an expanded maxillary ostium. The mass may contain areas of high density or calcification, and there may be sclerosis of the wall of the affected sinus. The main advantage of magnetic resonance imaging (MRI) is in defining the extent of the tumour, and in differentiating it from adjacent inflammatory tissue, but there are no certain signal intensity or enhancement characteristics to help differentiate inverted papilloma from sinus malignancy. In the differential diagnosis, antro-choanal polyp, malignant sinus tumours and chronic rhinosinusitis and fungal disease need to be excluded. The combination of bone deformity and sclerosis with the typical antro-meatal mass suggests a slow-growing tumour such as inverted papilloma.

Adult↗
PubMed2000

Optimum imaging and diagnosis of cerebrospinal fluid rhinorrhoea.

Imaging is an important component in the investigation of unilateral watery rhinorrhoea suspicious of cerebrospinal fluid (CSF). Whilst the demonstration of the presence of beta 2 transferrin confirms that CSF is present it may prove difficult to demonstrate the exact site of origin. Fine detail coronal computed tomography (CT) with sections of 1-2 mm thickness through the anterior skull base may show small dehiscences and fractures. The commonest site for congenital dehiscences is the cribriform niche adjacent to the vertical attachment of the middle turbinate anteriorly and the superior and lateral walls of the sphenoid posteriorly. In the presence of frequent or constant CSF rhinorrhoea a CT cisternogram can be helpful in defining the exact site of the leak. Magnetic resonance imaging (MRI) is reserved for defining the nature of soft tissue i.e. inflammatory tissue, meningoencephalocele or tumour. Finally, per-operative intrathecal fluorescein is helpful when imaging does not prove positive. A management algorithm for CSF rhinorrhoea is presented.

Adolescent↗
PubMed2000

Optimum imaging for mucoceles.

A mucocele is an epithelial lined mucus-containing sac completely filling a paranasal sinus and capable of expansion. They are relatively unusual, occurring most frequently in the fronto-ethmoidal region. The imaging features on plain X-ray, computerized tomography and magnetic resonance imaging are relatively characteristic allowing distinction of the lesion from other pathologies in this area although the mucoceles may occur in association with other pathologies such as nasal polyposis and neoplasia.

Ethmoid Sinus↗
PubMed2000

Optimum imaging for sinonasal malignancy.

A combination of computed tomography (CT) and magnetic resonance imaging (MRI) is now established as the optimum assessment of sinonasal malignancy. CT and MRI are of particular value in assessing the skull base, orbit and pteryo-palatine and infratemporal fossae. Although MRI offers better differentiation of tumour from surrounding tissue and fluid, coronal CT is still required for the demonstration of bone erosion particularly in the region of the cribriform plate. Thus the extent of local tumour spread may be determined with a degree of accuracy in excess of 98 per cent. However, the final determinant of penetration of the dura and orbital periosteum requires per-operative frozen section assessment. A knowledge of the tissue characteristics and site of origin can be of value in distinguishing some of the commoner sinonasal malignancies such as squamous cell carcinoma, adenocarcinoma, adenoid cystic carcinoma, olfactory neuroblastoma and chondrosarcoma. Imaging, particularly MRI also plays an important role in the post-therapeutic follow-up of patients, indicating areas of residual or recurrent disease, defining suspicious areas for biopsy. Post-operative surveillance is best achieved with three planar T1-weighted MRI, with, and without, gadolinium and axial T2-weighted sequences. The subtraction of the T1 pre- and post gadolinium T1 sequences can be of particular value in delineating recurrence.

Chondrosarcoma↗
PubMed2000

Imaging for juvenile angiofibroma.

Juvenile angiofibroma presents characteristic imaging signs, may of which allow diagnosis and accurate estimation of extent without recourse to the dangers of biopsy. The diagnosis by computed tomography (CT) is based upon the site of origin of the lesion in the pterygopalatine fossa. There are two constant features: (1) a mass in the posterior nasal cavity and pterygopalatine fossa; (2) erosion of bone behind the sphenopalatine foramen with extension to the upper medial pterygoid plate. Good bone imaging on CT is essential to show invasion of the cancellous bone of the sphenoid. This is the main predictor of recurrence: the deeper the extension, the larger the potential tumour remnant likely to be left following surgery. The characteristic features on magnetic resonance imaging (MRI) are due to the high vascularity of the tumour causing signal voids and strong post-contrast enhancement. MRI shows the pre-operative soft tissue extent of angiofibroma optimally, but its more important application is to provide post-operative surveillance: to show any residual or recurrent tumour, record tumour growth or natural involution and monitor the effects of radiotherapy.

Adolescent↗
PubMed2000

Impaired reading in patients with right hemianopia.

A left occipital stroke may result in alexia for two reasons, which may coexist depending on the distribution of the lesion. A lesion of the left lateroventral prestriate cortex or its afferents impairs word recognition ("pure" alexia). If the left primary visual cortex or its afferents are destroyed, resulting in a complete right homonymous hemianopia, rightward saccades during text reading are disrupted ("hemianopic" alexia). By using functional imaging, we showed two separate but interdependent systems involved in reading. The first, subserving word recognition, involved the representation of foveal vision in the left and right primary visual cortex and the ventral prestriate cortex. The second system, responsible for the planning and execution of reading saccades, consisted of the representation of right parafoveal vision in the left visual cortex, the bilateral posterior parietal cortex (left > right), and the frontal eye fields (right > left). Disruption of this distributed neural system was demonstrated in patients with severe right homonymous hemianopia, commensurate with their inability to perform normal reading eye movements. Text reading, before processes involved in comprehension, requires the integration of perceptual and motor processes. We have demonstrated these distributed neural systems in normal readers and have shown how a right homonymous hemianopia disrupts the motor preparation of reading saccades during text reading.

Adult↗
PubMed2000

Prospective allometric scaling: does the emperor have clothes?

We are not suggesting that an allometric relationship between pharmacokinetic parameters in animals and humans does not exist; we believe that it does. We are suggesting that using prospective AS to select doses in an FTIM study may lead to a false sense of security given the large publication bias in the literature. There are a number of unrecognized pitfalls to this approach, including (1) prediction intervals so wide as to be of limited use, (2) prediction error is often no better than arbitrarily chosen constants, and (3) it is not possible to determine which drugs will fail a priori. We encourage journals to publish studies in which prospective AS has failed so as scientists we may begin to see what makes these compounds different, with a goal toward better prediction of human pharmacokinetics.

Animals↗
PubMed2000

An acute stroke service: potential to improve patient outcome without increasing length of stay.

Acute stroke is associated with a high morbidity and mortality: up to 24% of patients may not survive their hospital admission. Stroke unit care has been shown in a meta-analysis to reduce this morbidity and mortality. We present a three-year audit of the first acute stroke service in an Irish teaching hospital. The audit was carried out prospectively on 193 patients admitted to the acute stroke service, from July 1996 to end of June 1999. Details regarding patients, type and severity of stroke, length of stay and outcome were collected prospectively on a standard pro-forma. We observed a reduction in mortality from 19% to 15% to 9%, and an increasing percentage of patients discharged home from 55% to 64% to 68%, in year 1, year 2 and year 3 respectively. A trend towards a greater number of patients, younger age and improved outcome with lower mortality was observed from year to year, without significant change in length of stay. This study confirms the value to patients of organised stroke care in terms of reduction in mortality and morbidity without increasing length of stay or disability. We suggest that every acute hospital should have organised stroke care.

Acute Disease↗
PubMed2000

The impact of waiting time on liver transplant outcomes.

OBJECTIVE: To measure the impact of patient waiting time on the probability of graft failure following liver transplantation. DATA SOURCES: Observations on all patients receiving transplants between 1995 and 1997 collected by the United Network for Organ Sharing. STUDY DESIGN: This study uses a two-stage probit algorithm. The first stage is an ordinary least squares regression of controls and indicators of patient blood type (the instrument set) on waiting time. The second uses the predicted value from the first regression in a probit analysis where the dependent variable is graft failure. PRINCIPAL FINDINGS: Waiting time has a statistically and clinically significant effect on the probability of graft failure following transplantation. Waiting 50 additional days for a transplant increases the probability of graft failure at one year by between one and two percentage points. CONCLUSIONS: Policies to reduce waiting times will yield clinical benefits beyond decreasing the length of time patients spend in poor health.

Algorithms↗
PubMed1999

The War Events Questionnaire.

BACKGROUND: The measurement of exposure to war in large epidemiological studies necessitates the use of easily administered and reliable questionnaires that cover a range of war events. The War Event Questionnaire (WEQ) was designed by our group to address these issues and has proved to be quite easy to administer. The aim of this study is to establish the inter-rater reliability of the WEQ. METHOD: Two trained interviewers alternated in administering parts I and II of the WEQ. RESULTS: The Kappa statistics used to calculate the degree of agreement between the two raters ranged from 0.281 to 0.774 for part I events and from 0.189 to 1.000 for part II events. CONCLUSION: The WEQ has proved to be a useful instrument that addresses both objective and the subjective war experiences; it is a fairly reliable instrument and has helped us avoid tautological assessment of the mental health effects of war.

Adolescent↗
PubMed1999

MR imaging of levator ani muscle recovery following vaginal delivery.

Our aim was to quantify the changes that occur in the levator ani muscles (LA) after vaginal delivery using magnetic resonance imaging. Fourteen women underwent MRI 1 day postpartum. Six of them were also scanned 1, 2, 6 weeks and 6 months after delivery. LA signal intensities and thickness, in areas of the urogenital and the levator hiatus were assessed in the transverse plane. Perineal body position was measured in the sagittal plane. One day postpartum a higher T2-signal intensity of the LA compared to the obturator internus muscle was found in all women and a lower T1-signal intensity in 8 of 12 women. By 6 months these differences were present in only 1 woman in the left LA. An elevation in perineal body position of 13.4 +/- 7.3 mm (P < 0.05), as well as a decrease in the area of the urogenital hiatus by 27% (P<0.05) and of the levator hiatus by 22% (P < 0.05) by 2 weeks postpartum suggest a return of normal LA geometry. LA thickness showed interindividual variations, and a complete loss of LA tissue was found in 1 woman. Changes in LA signal intensity, topography and thickness during the puerperium can be documented using MR imaging.

Adult↗