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Biomedical subjects

F Powell

Publications and source records attributed to F Powell.

At least 19 recordsLinked to original sources
PubMed1997

Predicting poor neonatal outcome: a comparative study of noninvasive antenatal testing methods.

OBJECTIVE: The assessment of fetal well-being in the third trimester of pregnancy depends on many variables including fetal size, amniotic fluid volume, umbilical cord arterial Doppler waveforms, the nonstress test, and the biophysical profile, yet little has been written that directly compares these variables. In this study, we compared amniotic fluid indexes, umbilical cord arterial Doppler waveforms, nonstress tests, and biophysical profiles for predicting poor neonatal outcomes in fetuses who are small for gestational age (SGA). SUBJECTS AND METHODS: From April 11, 1994, through August 1, 1995, a cohort of 108 SGA fetuses was identified. Follow-up was available in 97 of these cases. Receiver operating characteristic curves were constructed for Doppler systolic:diastolic ratios and for amniotic fluid indexes. Student's t test and logistic regression analysis were used to compare umbilical cord arterial Doppler imaging, amniotic fluid indexes, the nonstress test, and the biophysical profile for predicting poor neonatal outcome. RESULTS: Of the 30 fetuses who had poor outcomes, five were emergency cesarean deliveries, three died, three had intracranial hemorrhages, one had a cerebral infarct, 12 had prolonged admission to the neonatal intensive care unit (NICU) (> 10 days), and six had NICU admissions at term. Of the variables we assessed, the sensitivities for predicting poor outcome were as follows: cord Doppler imaging, 64%; low amniotic fluid volume (oligohydramnios), 32%; biophysical profile, 18%; and nonstress test, 14%. Receiver operating characteristic curves showed that a systolic:diastolic ratio of 4.0 and an amniotic fluid index of 5 cm (independent of gestational age) were the most accurate cutoff values for predicting poor outcome. Logistic regression analysis showed that amniotic fluid indexes and umbilical cord arterial Doppler imaging were independent predictors of poor outcome and that the predictive value of the biophysical profile varied according to the amniotic fluid index. CONCLUSION: Doppler waveform abnormalities were the most accurate predictor of poor neonatal outcome in a cohort of SGA fetuses. Umbilical cord arterial Doppler waveform analysis should be included in the surveillance of SGA fetuses.

Amniotic Fluid↗
PubMed1996

Clearance of recalcitrant psoriasis after tonsillectomy.

Infection is a well-recognized triggering factor for both guttate and chronic plaque psoriasis. We investigated prospectively 13 patients with recalcitrant psoriasis exacerbated by recurrent tonsillitis, who underwent tonsillectomy between 1990 and 1993. There were 12 female patients and one male, with a mean age of 17 yr (range 6-28). Six patients had guttate psoriasis resistant to standard treatments and seven patients had chronic plaque psoriasis exacerbated by tonsillitis that was severe enough to warrant at least one admission to hospital. Patients were followed by chart review and postal questionnaire. Psoriasis was cleared completely after tonsillectomy in five out of the six patients (83%) with guttate psoriasis and was improved in one patient. Two out of seven patients with plaque psoriasis (29%) were cleared, two (29%) were improved and three (42%) were unchanged. We conclude that tonsillectomy may be a successful treatment modality in selected patients with recalcitrant guttate or chronic plaque psoriasis.

Adolescent↗
PubMed1994

Distinct phenotype in maternal uniparental disomy of chromosome 14.

We report on the occurrence of maternal uniparental disomy for chromosome 14 (mUPD14) in a 4-year-old girl with a de novo Robertsonian translocation, 45,XX,t (13q,14q). The child has arrested hydrocephalus, short stature, minor anomalies, small hands with hyperextensible joints, and mild to moderate developmental delay. Comparison of her phenotype with those of three previously described individuals show some common distinct traits which suggest a mUPD14 syndrome.

Abnormalities, Multiple↗
PubMed1993

Multiple genes encode the major surface glycoprotein of Pneumocystis carinii.

The major surface antigen of Pneumocystis carinii, a life-threatening opportunistic pathogen in human immunodeficiency virus-infected patients, is an abundant glycoprotein that functions in host-organism interactions. A monoclonal antibody to this antigen is protective in animals, and thus this antigen is a good candidate for development as a vaccine to prevent or control P. carinii infection. We have cloned and sequenced seven related but unique genes encoding the major surface glycoprotein of rat P. carinii. Partial amino acid sequencing confirmed the identity of these genes. Based on Southern blot studies using chromosomal or restricted DNA, the major surface glycoproteins are the products of a multicopy family of genes. The predicted protein has an M(r) of approximately 123,000, is relatively rich in cysteine residues (5.5%) that are very strongly conserved, and contains a well conserved hydrophobic region at the carboxyl terminus. The presence of multiple related msg genes encoding the major surface glycoprotein of P. carinii suggests that antigenic variation is a possible mechanism for evading host defenses. Further characterization of this family of genes should allow the development of novel approaches to the control of this pathogen.

Amino Acid Sequence↗
PubMed1993

A quantitative immunohistochemical evaluation of lentigo maligna and pigmented solar keratosis.

Pigmented solar keratosis (PSK) is sometimes clinically indistinguishable from lentigo maligna, a form of malignant melanoma in situ. Occasionally histologic diagnosis is also difficult. Accurate diagnosis is essential, as the treatment and prognosis for each condition differs considerably. To determine whether there was a significant overlap in the number of melanocytes in these sun-damaged skin lesions, or whether immunohistochemistry might be helpful in the differential diagnosis, the authors examined skin biopsy specimens from 26 patients with obvious lentigo maligna and 15 patients with PSK using 3 monoclonal antibodies (HMB-45, NK1C3, and vimentin) and 1 polyclonal antibody (S-100 protein). Formalin-fixed paraffin sections were immunostained with each of the above antibodies, and immunopositive cells per mm2 of epidermis were counted. The difference between lentigo maligna and PSK counts was statistically significant at a level of P < .0001; furthermore, there was almost no overlap between the two groups. The sensitivity for the diagnosis of lentigo maligna was high with all antibodies. However, HMB-45 had the highest sensitivity and the lowest false-positive rate and was visually most pleasing. Using a cut-off count of 60 cells per mm2 of epidermis, HMB-45 had a sensitivity of 96% and a 0% false-positive rate. In this study, lentigo maligna was easily differentiated from PSK. The real value of immunohistochemistry in the differential diagnosis of these pigmented lesions should be tested in a prospective study using cases that are difficult to diagnose by routine light microscopy.

Adult↗
PubMed1993

Inhibition of Pneumocystis carinii dihydropteroate synthetase by para-acetamidobenzoic acid: possible mechanism of action of isoprinosine in human immunodeficiency virus infection.

Isoprinosine has been reported to decrease progression to AIDS, primarily by preventing Pneumocystis carinii pneumonia (PCP), in human immunodeficiency virus-infected patients, but the mechanism of action is unknown. para-Acetamidobenzoic acid (PAcBA), one component of isoprinosine, is structurally related to para-aminobenzoic acid (PABA), a precursor of de novo folate synthesis. This pathway is known to be important for P. carinii because sulfonamides, which are effective anti-P. carinii agents, inhibit incorporation of PABA into folate precursors by the enzyme dihydropteroate synthetase (DHPS). Inhibition of P. carinii DHPS by PAcBA was investigated by using two assays. In short-term cultures of P. carinii from rats, [3H]PABA incorporation into reduced folates was inhibited by both isoprinosine (mean +/- standard error 50% inhibitory concentration [IC50], 20 +/- 8.4 microM) and PAcBA free acid (IC50, 240 +/- 100 microM); a soluble PAcBA salt was more potent than PAcBA free acid alone (IC50, 29 +/- 48 microM). The activity of PAcBA free acid was confirmed in a cell-free DHPS inhibition assay (IC50, 120 +/- 120 microM). Inosine and dimethylaminopropanol, two other components of isoprinosine, were poor inhibitors of PABA incorporation (IC50, > 1,000 microM). PAcBA free acid also showed activity in inhibiting the DHPS of Toxoplasma gondii, but was a poor inhibitor of the DHPSs of Escherichia coli and Saccharomyces cerevisiae. In a rat model of PCP, the PAcBA salt administered intraperitoneally demonstrated no activity against established PCP either alone or when used in combination with trimethoprim; the lack of efficacy in this model may be due to the rapid metabolism of the drug. Prevention of PCP by PaCBA through inhibition of P. carinii DHPS may explain the activity of isoprinosine in decreasing the progression to AIDS in human immunodeficiency virus-infected patients.

4-Aminobenzoic Acid↗
PubMed1990

Kerion--clinical spectrum in nine cases.

The clinical features, microbiology and outcome of nine cases of kerion are reviewed. The aetiology of this uncommon condition, and the role of various therapeutic modalities are discussed. Clinicians need to be aware of the varying presentations of inflammatory fungal disease to avoid misdiagnosis as bacterial infection.

Adult↗
PubMed1977

Ventilatory responses to CO2 in the chicken: intrapulmonary and systemic chemoreceptors.

The independent effects of pulmonary and arterial Pco2 on respiratory amplitude (RA) and respiratory frequency (f) were studied in unidirectionally ventilated chickens anesthetized with phenobarbital (160 mg-kg-1). Pulmonary Pco2 was set by the level of PIco2 ventilating the vascularly isolated right lung (VIL), whereas the systemic arterial Pco2 was set by the level of PIco2 ventilating the denervated left or gas exchange lung (GEL). The following results were obtained: 1) Increasing the PIco2 to the VIL from 0 to 35 torr and maintaining Paco2 constant at 2. torr increased RA from apnea to 76% of the animals' maximal hypercapnic response and decreased f: further increases in PIco2 to VIL had only minimal effects on RA and f. 2) increasing Paco2 from 19 to 61 torr and maintaining pulmonary Pco2 constant increased RA and decreased further increases in Paco2 had only slight effects on RA ulmonary chemoreflex and can dominate the control of RA during hypocapnic conditions, and (2) systemic CO2-sensitive chemoreceptors dominate the control of RA during hypercapnic conditions. It is suggested that the intrapulmonary chemoreceptors may act as a sensory system which plays a pertinent role in the regulation of parabronchial ventilation.

Animals↗
PubMedDate not supplied

A clinicopathological correlation of 134 stage 1 and 79 non-invasive cutaneous melanomas presenting over a decade (1984-1993) at the Mater Misericordiae Hospital, Dublin.

In a study of malignant melanoma during the period 1984-1993, 134 (63 per cent) had invasive melanoma and in 79 (37 per cent) melanoma was confined to the epidermis (in situ). There was female predominance, F: M = 2.4 : 1, a family history of melanoma in 1.5 per cent, a mean age at diagnosis of 50 yr. Females presented a decade earlier than males on average. Over half of invasive melanomas in females occurred on lower limbs; 40 per cent of lesions in males occurred on the trunk. Almost one third of lesions in males and over two thirds in females occurred in sun exposed area. Sixty per cent of invasive lesions were of the superficial spreading type and half of all lesions were histologically thin [less than 1.5 mm vertical depth]. Surprisingly, median lesion thickness was lower in males, probably reflecting the greater frequency of nodular lesions in females compared to males (36 per cent -v- 24 per cent). The marked increase in the number of invasive melanoma patients presenting in the second half of the decade studied (treble that of the first half) probably reflects an increase in melanoma incidence. Over the decade no change in invasive melanoma type, anatomical site or histological thickness was noted, the latter suggesting a failure to diagnose melanoma at an increasingly earlier stage. An official melanoma public education programme is required, particularly as half of the patients delayed 1 yr or more before seeking medical advice. However it is encouraging that, of the invasive melanomas, 30 per cent were small (< 10 mm), 50 per cent were histologically thin and that 37 per cent of all melanomas were in situ. The melanoma-in-situ group had a similar gender ratio and mean age at diagnosis to the invasive melanoma patients but lesions were smaller, were predominantly on the head, neck and limbs with lentigo melanoma as the commonest type.

Adolescent↗