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Biomedical subjects

J R Alexander

Publications and source records attributed to J R Alexander.

At least 37 records · Page 2Linked to original sources
PubMed1990

Cardiorespiratory patterns in infants presenting with apparent life-threatening episodes.

A total of 305 infants presenting with apparent life-threatening events (ALE) were referred by their paediatricians and underwent 24-hour tape recordings of electrocardiogram and abdominal breathing movements (from a pressure capsule transducer). Seventy-seven of these infants, all full-term (greater than or equal to 37 weeks of gestation), were randomly selected, followed up for clinical outcome, and their recordings subjected to a detailed analysis of heart and respiratory rates and breathing patterns. Recordings on 157 age-matched, full-term controls were similarly analysed for comparison purposes. One of the 77 patients suffering from ALE had a pre-existing neurodevelopmental problem, and 4 more cases showed this at follow-up, including 1 case whose ALE was subsequently diagnosed as originating from non-accidental injury. Compared with controls and as a group, the patients suffering from ALE showed higher numbers of apnoeic pauses (p less than 0.001), larger quantities of periodic breathing (p less than 0.01) and lower respiratory rates during regular breathing (p less than 0.01).

Apnea↗
PubMed1989

High prevalence of adenomatous polyps of the duodenal papilla in familial adenomatous polyposis.

Eighteen consecutive asymptomatic patients with familial adenomatous polyposis (both familial polyposis coli and Gardener's syndrome) were studied over a 12-month period; side-viewing upper endoscopy and biopsy were used to assess the frequency of adenomatous polyps of the duodenal papilla. Nine of the 18 patients demonstrated adenomatous polyps of the papilla, varying in size and appearance from microadenomas in normal-appearing duodenal papillae (two) to a sessile polyp 3 cm in diameter. Two were tubulovillous adenomas (0.5 cm and 2 cm in diameter) and the remainder were tubular adenomas. Severe atypia and malignancy were not encountered. These findings reveal that adenomas of the duodenal papilla are common in individuals with familial adenomatous polyposis. Because of these findings and because of the known risk of periampullary adenocarcinomas and nonmalignant complications of polyps of the duodenal papilla in patients with familial adenomatous polyposis, upper gastrointestinal screening of such patients should include examination of the duodenal papilla with a side-viewing endoscope.

Adenomatous Polyposis Coli↗
PubMed1989

Town vs gown.

Explore the source record for details and available documents.

Ambulatory Care Facilities↗
PubMed1989

Perforated duodenal ulcer after gastric bypass surgery.

Gastric bypass procedures have been used widely in the surgical therapy of morbid obesity. Evidence exists that the bypassed gastric segment retains its ability to secrete acid. Acid-related ulceration and obstruction of the proximal gastric pouch after surgery have been well documented, but duodenal ulceration after gastric bypass has yet to be reported. We present the first reported case of duodenal ulceration and perforation after gastric bypass surgery for morbid obesity. This case demonstrates that acid-related gastroduodenal disease may occur in the bypassed gastrointestinal tract. Consideration should be given to this area in evaluating upper gastrointestinal bleeding and abdominal pain after gastric bypass. Because barium contrast studies may not adequately evaluate bypassed segments, and standard gastroscopes are not long enough to reach these areas, the use of longer endoscopes may be necessary to confirm the presence of gastroduodenal disease after gastric bypass.

Adolescent↗
PubMed1987

Cardiorespiratory patterns in siblings of babies with sudden infant death syndrome.

Clinical data and 24 hour tape recordings of electrocardiogram (ECG) and abdominal breathing movements were collected from 301 infants who had had a sibling who had suffered the sudden infant death syndrome (SIDS). Of these, 261 were referred cases, and 40 were recorded prospectively as part of a population based study; none of the 301 subsequently died. Fifty five of the referred siblings who had been born at full term (greater than or equal to 37 week gestation) were randomly selected for a detailed analysis of heart rate and breathing patterns, as were all siblings born at full term from the prospective study (16 with a previous sibling in whom SIDS had occurred and seven with a sibling born at full term and in whom SIDS had subsequently occurred). The control group consisted of 197 recordings on 170 infants born at full term and matched by postnatal age. The mothers of the siblings smoked and consumed alcohol more often during pregnancy than the mothers of control babies. The siblings had lower Apgar scores and were more often breast fed than controls. There were no significant differences in the number of apnoeic pauses in the quantities of periodic breathing or in the heart and respiratory rates during regular breathing between the siblings and the controls.

Aging↗
PubMed1987

Pulse oximeter and transcutaneous arterial oxygen measurements in neonatal and paediatric intensive care.

Pulse oximeter (SaO2P) measurements were compared with direct arterial line oxygen saturation (SaO2) from co-oximeters in 92 instances in 43 patients, and with arterial line oxygen measurements (PaO2) in 169 instances in 81 patients. The mean (SD) absolute difference between SaO2P and SaO2 was 2.6% (2.4) after attempt to correct for the co-oximeter falsely measuring a proportion of fetal haemoglobin as carboxy haemoglobin. For 19 infants and children greater than or equal to 5 months old, who have very little fetal haemoglobin, the mean (SD) absolute difference of 27 comparisons was 1.8% (2.1). Comparison of SaO2P and PaO2 measurements in 46 instances when PaO2 was less than 6.67 kPa showed SaO2 to be less than 90% on 40 occasions. In 24 instances when PaO2 was greater than or equal to 13.3 kPa the SaO2P was greater than or equal to 98% on 22 occasions. In 23 infants undergoing neonatal intensive care, transcutaneous oxygen monitors were compared with arterial PO2 measurements in 60 instances. The mean (SD) absolute difference between PaO2 and transcutaneous oxygen measurements was 1.60 kPa (1.73). Ten of the 60 comparisons had differences greater than 2.67 kPa and three greater than 5.33 kPa (maximum 8.40 kPa). Pulse oximetry is a clinically useful technique for managing oxygenation but further studies are needed to confirm its safety in premature infants at risk of retinopathy of prematurity.

Adolescent↗
PubMed1987

Pre- and perinatal clinical characteristics of infants who suffer sudden infant death syndrome.

In a population-based study, clinical and physiological data were collected in the neonatal period on 7,496 full-term (greater than or equal to 37 weeks) infants of birthweights greater than 2.50 kg born in 3 hospitals. The sample excluded a small number of infants who were born with severe illnesses from which there was no period of recovery before death in the neonatal period. Twenty-seven of the infants had died by the time all of the population had passed their third birthday. Twenty-one of these cases died suddenly and unexpectedly, and in 13 there was no adequate explanation for death (sudden infant death syndrome-SIDS). Pre- and early postnatal clinical data on the infants who had died were compared to a randomly selected sample of 478 survivors. This analysis showed that the infants who suffered SIDS showed similar clinical characteristics to those previously reported. Unlike the SIDS group, however, the prenatal histories of the non-SIDS deaths were similar to controls, showing no evidence of a sub-optimal intra-uterine environment.

Child, Preschool↗
PubMed1986

QT interval measurements before sudden infant death syndrome.

Standard electrocardiogram recordings were performed on a total of 7254 newly born infants from two maternity hospitals. Fifteen recordings were obtained on 15 infants who subsequently suffered sudden infant death syndrome. None showed lengthening of QT intervals sufficient to warrant the description of 'long QT syndrome'. When the QT intervals corrected for heart rate of cases with sudden infant death syndrome were compared with controls in age matched groups or after individual matching for postnatal age, hospital of birth, and weight at birth, no significant differences could be identified.

Electrocardiography↗
PubMed1986

Cardiorespiratory patterns occurring in infants during and after recovery from respiratory tract infection.

During and after respiratory tract infections in 29 hospitalized infants, 12 cardiorespiratory measurements were performed on 24-hour recordings of ECG and respiratory activity. These measurements were compared with similar data obtained from 110 age-matched control infants without infection. Respiratory and heart rates during the state of regular breathing were increased during infection, as compared with recordings made after recovery. The numbers of short apneic pauses 3.6 to 6.0 seconds and greater than 6.0 to 12.0 seconds in duration, together with the duration of the overall longest apneic pause per recording, were reduced during infection compared with after recovery. The total durations of periodic breathing and of periodic apnea per recording were also reduced during infection compared with after recovery. These effects were consistent in 27 of the 29 cases, but in two, periodic breathing levels during infection exceeded the 90th percentile in age-matched controls and were reduced after recovery. Measurements made after recovery tended to conform more closely to values in the control infants. None of the 29 infants studied subsequently died or suffered chronic respiratory problems. This study suggests that prolonged apneic pauses or increased numbers of short pauses are not usually a consequence of respiratory tract infection in normal infants.

Apnea↗
PubMed1986

Cardiorespiratory function in 16 full-term infants with sudden infant death syndrome.

Twenty-four-hour tape recordings of ECG and breathing movements from 16 term infants (greater than or equal to 37 weeks' gestation) who subsequently died of sudden infant death syndrome (SIDS) were compared with recordings from surviving infants from the same populations. Apneic pauses of varying durations, periodic and regular breathing patterns, heart and respiratory rates during regular breathing were measured. Only one of 16 full-term infants with SIDS had findings outside the range of age-matched control infants (an excess of periodic breathing patterns and an absence of regular breathing). When the first recordings of each of infants who died of SIDS, except one who had cyanotic episodes prior to death, were compared to recordings of survivors (six for each case) closely matched for age, gestation, and weight at birth, no differences in breathing patterns or heart or respiratory rates during regular breathing could be demonstrated. These particular measurements of cardiorespiratory function were, therefore, unable to identify the majority of full-term infants at risk for SIDS.

Apnea↗
PubMed1986

Photoperiod and body weight in female Syrian hamsters: skeleton photoperiods, response magnitude, and development of photorefractoriness.

Two experiments examined the effects of various photoperiods on body weight and reproductive function in Syrian hamsters (Mesocricetus auratus). In Experiment 1 female hamsters were exposed to symmetrical skeleton photoperiods in which dawn and dusk were mimicked by 1-hr light pulses. A skeleton long (LD 16:8) photoperiod had no effect on body weight or estrous cyclicity (compared with animals in a complete LD 16:8 photoperiod), but exposure to a skeleton short (LD 10:14) photoperiod increased body weight and interrupted estrous cycles. Thus, body weight appears to respond to the relative timing of the two light pulses (a circadian mechanism) rather than to the absolute amount of light or darkness (an hourglass mechanism), just as does reproduction. In Experiment 2 female hamsters were exposed to a long photoperiod (LD 16:8) or to one of two short photoperiods (LD 10:14 and LD 8:16). Both short photoperiods increased body weight and interrupted estrous cycles, but the LD 8:16 photoperiod was substantially more effective at increasing body weight than was the LD 10:14. Thus, hamster body weight appears to be capable of a graded response to photoperiod, with shorter days producing a greater obesity. With prolonged exposure to the two short photoperiods (greater than 30 weeks), body weights spontaneously returned to the same level as the long-day controls, and estrous cycles resumed. When these hamsters were treated with the pineal gland hormone, melatonin, only those housed in long days exhibited the characteristic body weight gains, growth of brown and white adipose tissues, and decreases in uterine weight. Therefore, with prolonged exposure to short days, energy balance develops a photorefractoriness and an insensitivity to melatonin treatment, just as with reproductive function.

Adipose Tissue, Brown↗
PubMed1984

Disseminated histoplasmosis associated with the acquired immune deficiency syndrome.

Disseminated histoplasmosis developed in a previously healthy man as the initial manifestation of the acquired immune deficiency syndrome. Following apparently successful therapy with intravenous amphotericin B, he presented two months later with a subacute pneumonitis syndrome diagnosed by bronchoscopy as Pneumocystis carinii pneumonia. He showed response to intravenous trimethoprim/sulfamethoxazole with resolution of his symptoms and clearing of chest radiographic findings. While he was receiving antibiotics, oral candidiasis developed and has persisted for more than two months despite topical therapy and discontinuation of all antibiotics.

Acquired Immunodeficiency Syndrome↗
PubMed1984

Sequential 22-hour profiles of breathing patterns and heart rate in 110 full-term infants during their first 6 months of life.

Sequential recordings (total number 365, mean duration 22 hours) of ECG and abdominal wall movement were obtained from 110 full-term infants up to 6 months of age. The longest pause in breathing movement per recording (maximum 21.6 seconds) decreased in duration over the first 2 weeks of life (P less than .005). Pauses greater than 18.0 seconds were not detected after seven days. The spread of values for pauses greater than or equal to 3.6 seconds duration was widest during the first 2 weeks, and their number decreased with age (P less than .001). Periodic breathing, detected in 69% to 80% of infants in all age groups, showed decreasing trends with age in total duration and maximum length of episode (P less than .005 for both). The spread of values was widest during the first 2 weeks (range for total duration 0 to 4.7 hours) and decreased with age. The mean respiratory rate during regular breathing decreased after 4 weeks (P less than .001). The spread of values was widest during the first 2 weeks and decreased with age. Birth weight was positively correlated with mean respiratory rate during the first three days of life (r = +.64, P less than .001). The mean heart rate during regular breathing increased during the first 15 days (P less than .001) and then decreased after 4 weeks (P less than .001). Higher mean heart rates were found in male infants (P less than .01).

Abdominal Muscles↗
PubMed1983

Undetected episodes of prolonged apnea and severe bradycardia in preterm infants.

Twenty-four-hour tape recordings of ECG and breathing movement were made on 14 preterm infants with prolonged apneic episodes. Despite apnea monitoring systems, 136/203 (67%) apneic episodes greater than or equal to 20 seconds in duration, including 19 episodes greater than or equal to 50 seconds in duration, were not recorded by nursing staff. Of 120 apneic episodes greater than or equal to 30 seconds, 100 (89%) were accompanied by bradycardia less than or equal to 100 beats per minute. Episodes of more marked bradycardia (less than or equal to 80 beats per minute and up to seven minutes in duration) occurred without cessation of breathing movement in 10/14 infants studied. Treatment with theophylline or aminophylline was associated with a reduction in the number of episodes of apnea greater than or equal to 20 seconds accompanied by bradycardia less than or equal to 80 beats per minute (P less than .001). Many prolonged episodes of apnea and bradycardia are going unnoticed in neonatal intensive care units. Further studies are required to investigate and overcome the causes of these failures.

Aminophylline↗