Recent advances in intensive care. Percutaneous tracheostomy may not be more effective than open technique.
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Critical Care↗
Biomedical subjects
D Howard
Publications and source records attributed to D Howard.
Why is a verb like an inanimate object? Grammatical category and semantic category deficits.
Semantic category effects, such as difficulties in naming animate things relative to inanimate objects, have been explained in terms of the relative weightings of perceptual and functional features within the semantic representations of these concepts. We argue that grammatical category deficits, such as difficulties in naming nouns relative to verbs, can be explained within the same framework. We hypothesize that verb concepts are richer in functional than sensory features and present a model of the semantic representations of animate nouns, inanimate nouns, and verbs. The model demonstrates that sensory feature damage results in a deficit for naming living things but spares verb naming, and functional feature damage results in a deficit for naming inanimate objects and verbs. We then report the assessment results of two patient groups. In accordance with the model's predictions, the "verb spared" patients were consistently worse at naming living things than inanimate objects, and their definitions of both living and nonliving items were lacking in sensory information. We conclude that damage to sensory features in semantic representations causes difficulties in naming concrete nouns relative to action verbs, and within the grammatical category of nouns, animate items will be more severely affected. Imageability was shown to be a strong predictor of naming performance in the "verb deficit" patients, and when this variable was controlled no class effect remained. Production of definitions revealed no differential damage to sensory or functional features, and no consistent effect of animacy in naming was shown. While the model suggests that verb deficits might occur in patients for whom functional features are damaged relative to sensory features, we conclude that the "verb deficit" shown in our patients (and potentially in many previously reported cases) was an artifact of the lower imageability of verbs in confrontation naming tasks.
Aged↗
Noun imageability and the temporal lobes.
We used positron emission tomography to investigate brain activity in response to hearing or reading nouns of varying imageability. Three experiments were performed. Activity increased with noun imageability in the left mid-fusiform gyrus, the lateral parahippocampal area in humans, and in the rostral medial temporal lobes close to or within perirhinal cortex. The left mid-fusiform activation has been observed in previous imaging studies of single word processing. Its functional significance was variously attributed to semantic processing, visual imagery, encoding episodic memories, or the integration of lexical inputs from different sensory modalities. These hypotheses are not mutually exclusive. The more rostral medial lobe response to noun imageability has not been observed previously. However, lesions in perirhinal cortex impair knowledge about objects in non-human primates, and bilateral rostral ventromedial temporal lobe potentials in response to object nouns were observed with human intracranial recordings. Imageable (object) nouns are learnt with reference to sensory experiences of living and non-living objects, whereas acquisition of the meaning of low imageable (abstract) nouns is more dependent on their context within sentences. Parahippocampal and perirhinal cortices are reciprocally connected with, respectively, second and third order sensory association cortices. We conclude that access to the representations of word meaning is dependent on heteromodal temporal lobe cortex, and that during the acquisition of object nouns one route is established through ventromedial temporal cortical regions that have reciprocal connections with all sensory association cortices.
Adult↗
Racial differences in the structure and function of the stress urinary continence mechanism.
OBJECTIVE: To compare the structure and function of the urethral sphincter and the urethral support in nulliparous black and white women. METHODS: Eighteen black women (mean age 28.1 years) and 17 white women (mean age 31.3 years) completed this cross-sectional study. The following assessments were made: urethral function using multichannel cystometrics and urethral pressure profilometry, pelvic muscle strength using an instrumented speculum, urethral mobility using the cotton-swab test and perineal ultrasound, and pelvic muscle bulk using magnetic resonance imaging. RESULTS: Black women demonstrated a 29% higher average urethral closure pressure during a maximum pelvic muscle contraction (154 cm H(2)O versus 119 cm H(2)O in the white subjects; P =.008). Although not statistically significant, black women had a 14% higher maximum urethral closure pressure at rest (108 cm H(2)O versus 95 cm H(2)O; P =.23) and a 21% larger urethral volume (4818 mm(3) versus 3977 mm(3); P =.06). In addition, there was a 36% greater vesical neck mobility measured with the cotton-swab test (blacks 49 degrees versus whites 36 degrees; P =.02) and a 42% difference in ultrasonically measured vesical neck mobility during a maximum Valsalva effort (blacks = -17 mm versus whites -12 mm; P =.08). CONCLUSION: Functional and morphologic differences exist in the urethral sphincteric and support system of nulliparous black and white women.
Adult↗
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↗
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↗
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↗
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↗
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↗
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↗
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↗
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↗
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↗
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↗
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↗
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↗
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↗