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Biomedical subjects

P Duffty

Publications and source records attributed to P Duffty.

At least 19 recordsLinked to original sources

Respiratory function parameters in infants using inductive plethysmography.

A signal processing technique has been developed to determine respiratory function parameters by processing displacement data obtained from the abdomen and the rib cage of infants using respiratory inductive plethysmography. The technique transforms time-variant signals into the frequency domain, where they are filtered to reduce unwanted signal components. The phase relationship between the abdominal displacement and the rib cage displacement is determined from the phases of the filtered signals. Flow-volume loops, which are currently of great interest in respiratory medicine, are obtained from waveforms representing respiratory tidal flow and respiratory tidal volume. The index of respiratory timing is determined from a waveform representing respiratory tidal flow. The technique has been verified by statistical comparison with data simultaneously obtained using pneumotachography in a clinical study involving 49 infants.

Artifacts

Family studies in chromosome 22q11 deletion: further demonstration of phenotypic heterogeneity.

We describe three unrelated, Scottish infants with the velocardiofacial/DiGeorge syndrome, all of whom have deletions of chromosome 22q11. Two of the infants had inherited the deletion from their mothers; the third infant's mother had clinical features although a deletion was not demonstrable in her. One infant had craniosynostosis associated with broad thumbs which may be a separate familial trait; however, at least one other 22q11 deleted individual with craniosynostosis is known and it is possible that craniosynostosis is a rare feature of this deletion syndrome. The second infant is the third reported case with isolated hypoparathyroidism and dysmorphic features associated with the 22q11 deletion. The variable clinical phenotype of these families with 22q11 deletion is discussed and compared with other reported families.

Adult

Comparison of IgG subclasses in foetal serum, maternal serum at delivery and milk in IgA-deficient and control women.

Immunoglobulin G subclass concentrations were measured in paired foetal (cord) and maternal serum specimens at delivery from 27 IgA-deficient (serum IgA < 0.01 g/l) and 15 control women. IgA-deficient women had significantly higher serum IgG1 and IgG3 concentrations than control women but 2 of the group had concomitant IgG2/IgG4 deficiency and a further 12 had low IgG4 concentrations (serum IgG4 < 0.025 g/l). Foetal serum also had significantly higher IgG1 concentrations than control foetal serum but lower IgG2 and IgG4 levels. Concentrations of IgG subclasses and IgM were measured in breast milk collected on the fifth day postpartum from 19 of these IgA-deficient and 18 control women. Between-group differences in IgG subclass levels resembled those in serum. Compared with serum, proportionally less IgG3 was present in milk in both groups although the contribution of IgG3 to total IgG was not less than that of IgG4. Slightly higher IgM was found in milk from the IgA-deficient mothers.

Case-Control Studies

Weyers' ulnar ray/oligodactyly syndrome and the association of midline malformations with ulnar ray defects.

We describe a two generation family with variable ulnar and radial ray reduction and midline craniofacial abnormalities. The features suggest a diagnosis of Weyers' ulnar ray/oligodactyly syndrome originally described in two isolated cases. Syndromes of ulnar ray reduction are briefly reviewed and the relationship between limb bud and midline development discussed.

Abnormalities, Multiple

Reduced erythrocyte superoxide dismutase activity in low birth weight infants given iron supplements.

Erythrocyte superoxide dismutase (ESOD) activity reflects copper utilization and the risk of copper deficiency. To investigate the possible effects of inorganic iron on the metabolism of copper in low birth weight infants, we have measured ESOD activities in three groups of infants receiving different iron supplements. Fifty-five low birth weight infants were randomly assigned to receive daily from 28 d either 13.8 mg (HiFe), 7 mg (MidFe), or no elemental iron (NatFe) as iron edetate. At 27 d, 8, 12, and 20 wk postnatal age, infants were weighed and measured and hematologic indices, plasma ferritin, zinc, and copper concentrations, and ESOD activities were assayed. Anthropometrical and hematologic indices and plasma copper and zinc concentrations did not differ among treatment groups at any time, but at 20 wk, plasma ferritin concentrations [(micrograms/L) mean; SD] were lower in the NatFe group (17; 2.0) than in the HiFe group (32; 1.9: 95% confidence interval for mean difference 6.6 to 22.0, p less than 0.01). ESOD activities (U/g Hb) were similar in HiFe (1447; 263), MidFe (1552; 322), and NatFe (1538; 382) groups at 27 d, but by 20 wk activities in the HiFe group (1537; 211) were lower than in the MidFe (1789; 403: 95% confidence interval 38 to 466, p less than 0.05) and NatFe (1858; 304: 95% confidence interval 150 to 492, p less than 0.01) groups. The lower ESOD activities found in the HiFe group at 20 wk may reflect altered copper metabolism induced by the iron supplement, but the clinical importance of this observation is unknown.

Copper

Surgical treatment of necrotizing enterocolitis: a population-based study in the Grampian region, Scotland.

Ninety-two cases of necrotizing enterocolitis (NEC) were diagnosed in the Grampian Region of Scotland between 1978 and 1984, for a regional incidence of 2.2/1,000 live births. Twenty-seven cases (29.3%) required surgery, 19 acutely and eight for delayed stricture. Acute operative mortality was 10.5%. Disease-related mortality was 3.3%, and overall mortality was 8.7%. Follow-up ranged from 15 to 77 months for surgical patients, with only three of 23 survivors having increased bowel frequency.

Enterocolitis, Pseudomembranous

Glucagon for hypoglycaemia in infants small for gestational age.

Twenty five infants who were small for gestational age received glucagon (0.5 mg/day by continuous infusion) in the treatment of hypoglycaemia. Twenty responded within three hours with a rise in blood glucose concentration to above 4 mmol/l. Five subjects subsequently required hydrocortisone to maintain glucose concentrations. Rebound hypoglycaemia occurred in nine infants after rapid discontinuation of glucagon or interruption of the intravenous infusions. Response was poor after maternal beta blockade.

Blood Glucose

Pharyngeal dermoid leading to respiratory failure in a neonate.

Difficulty in resuscitating a neonate using bag and mask ventilation was followed by later episodes of apnoea and cyanosis. Intubation relieved the respiratory failure and revealed a large fleshy polyp obstructing the posterior pharynx. Computerised tomography showed there was no superior extension of the lesion and the polyp was removed completely on operation. Histological examination showed this lesion to be a dermoid or "Hairy Polyp".

Apnea

Effects of a face mask and pneumotachograph on breathing in sleeping infants.

The effect of facial attachments on breathing was measured by respiratory induction plethysmography (RIP) during quiet sleep in 32 studies in 18 infants. The addition of a face mask plus pneumotachograph led to an increase in tidal volume (VT) (22.0 +/- 13.5%, p less than 0.01) during 5-min sleep studies when compared to measurements using RIP alone. Applying only the mask rim also led to an increase in VT (14.6 +/- 3.1%, p less than 0.05). A significant increase in VT was noted in 3 of 6 infants studied when a lightweight cardboard ring was in place perinasally. Respiratory frequency fell significantly in the mask/pneumotachograph group (-5.9 +/- 10.0%, p less than 0.05) and with the mask rim (-7.4 +/- 8.8%, p less than 0.01), but there was individual infant variation. Minute ventilation rose significantly (19.1 +/- 16.9%, p less than 0.01) only with the addition of the mask and pneumotachograph. Instrument deadspace can account for some of the increase in VT noted, but in its absence, sensory stimulation of the trigeminal area can augment tidal breathing.

Humans

Hyaline membrane disease treated with bovine surfactant.

Six preterm infants with severe hyaline membrane disease requiring ventilation were treated, at a median age of 15.5 hours, with a single intratracheal bolus of a bovine surfactant suspension. Arterial oxygenation increased dramatically, and chest radiograms showed improvement after two to four hours. However, a variable degree of deterioration occurred within 24 hours. All of the infants required oxygen therapy for several weeks, and one developed severe bronchopulmonary dysplasia.

Animals