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Biomedical subjects

J MacDonald

Publications and source records attributed to J MacDonald.

At least 37 records · Page 2Linked to original sources
PubMed2001

Alveolar metabolism of natural vs. synthetic surfactants in preterm newborn rabbits.

We compared the recoveries of four surfactant preparations: two natural [term fetal rabbit surfactant (FRS) and adult rabbit surfactant (ARS)] and two commercially available preparations [apoprotein-based Survanta (S) and synthetic Exosurf (E)] from 27-day gestation rabbit pups treated at birth and ventilated up to 120 min. At 5, 60, and 120 min, we measured the recovery of the heavy-aggregate, metabolically active form (H) and the light-aggregate, nonsurface active metabolic breakdown form (L) of alveolar surfactant and determined the phospholipid content and composition of the intracellularly stored lamellar body (LB) pool. Pups treated with FRS had <15% loss of H by 2 h. ARS-treated pups had a >50% loss of H by 1 h, and E- and S-treated pups had approximately 50% loss by 5 min, with a slower rate of continuing loss of up to 80% by 2 h. The major losses of H phospholipid were not explained by the L-form recovery. LB phospholipid significantly increased only in the E-treated pups and only at 2 h. FRS provides a biologically active form (H) of surfactant that appeared to remain in the airway for a significantly longer time than the other surfactant preparations. The unique properties of FRS merit further study.

Animals↗
PubMed2001

Epidermal growth factor in the lungs of infants developing chronic lung disease.

Growth factors important to lung growth and fibrosis have been poorly studied in chronic lung disease (CLD) of prematurity. Epidermal growth factor (EGF) promotes epithelial cell maturation, and vascular endothelial growth factor (VEGF) is important in angiogenesis. The concentration of these growth factors was determined in 111 bronchoalveolar lavage fluid (BALF) samples from 35 ventilated infants: 13 developed CLD (median gestation 27 weeks, birthweight 820 g), 16 developed and recovered from respiratory distress syndrome (RDS) (31 weeks, 1,415 g) and six control infants (33 weeks, 2,075 g) were ventilated for nonpulmonary reasons. At birth, EGF in BALF from the CLD and RDS infants was lower than in the control infants (control versus CLD, 7.3 versus 0.0 pg x mL(-1), p<0.01; control versus RDS, 7.3 versus 5.0, p=0.08). EGF increased in all groups with a more rapid increase in control infants. A close relationship was noted between BALF EGF and gestational age (R=0.73). VEGF was undetectable at birth but increased at a similar rate in all three groups and did not correlate with gestation. In conclusion, these data suggest that epidermal growth factor is closely correlated to gestation and that it may predispose preterm infants to develop chronic lung disease.

Bronchoalveolar Lavage Fluid↗
PubMed2001

Diagnosis and surgical treatment of thyroid adenoma-induced hyperthyroidism in a green iguana (Iguana iguana).

An adult female green iguana (Iguana iguana) presented with polyphagia, loss of the dorsal spines, hyperactivity, increased aggression, tachycardia, and a bilobate mass palpable anterior to the thoracic inlet. Diagnosis of hyperthyroidism was based on a total T4 (30.0 nmol/L) elevated above that of clinically healthy iguanas (3.81 +/- 0.84 nmol/L), and histopathology confirmed a functional thyroid adenoma. Surgical thyroidectomy safely returned the lizard to a euthyroid state.

Adenoma↗
PubMed2001

Idiopathic hepatic uptake of (99m)Tc methylene diphosphonate: a case report.

OBJECTIVE: Two sequential (99m)Tc methylene diphosphonate (MDP) scans were performed on a 42-y-old woman with insulin-dependent diabetes mellitus, chronic right pyelonephritis and anemia. The initial scan showed reduced skeletal uptake with intense and diffuse hepatic uptake. Because these findings were similar to those seen when excessive hydrolyzed-reduced (99m)Tc colloids are present in the radiopharmaceutical, the scan was repeated after an adequate time delay. Increased skeletal uptake was evident in the second scan, but the hepatic uptake persisted. Although there are numerous causes of soft tissue activity on (99m)Tc MDP bone scans, the responsible pathologic entity is not always clear. This study reviews several possible reasons for such uptake, although the exact mechanism in this case remains conjectural.

Adult↗
PubMed2000

Psychiatric training in New Zealand.

OBJECTIVE: The aims of this study were to develop a profile of current psychiatric trainees in New Zealand, to identify factors important in their recruitment to and retention in psychiatric training and to identify factors that predict failure to complete training. METHOD: A survey was sent to all current psychiatric trainees in New Zealand and to all trainees who could be traced who had left psychiatric training in New Zealand In the last 5 years without completing the Fellowship of the Royal Australian and New Zealand College of Psychiatrists. RESULTS: General characteristics of the two groups are presented, as well as information about recruitment, burnout, general health and experiences of work and training. The only significant difference in general characteristics between the two groups was that more of those who had left training prematurely had been born overseas. The levels of family and personal mental illness were high, but there was no difference in these rates between those who had stayed in training and those who had left permaturely. Most trainees had decided to pursue a psychiatric career during their house-officer years. The most important factors determining the choice of a career in psychiatry were philosophical interest and house-officer experience in psychiatry. With respect to retention, despite high rates of burnout and psychological morbidity, and dissatisfaction with various aspects of the work setting, 94% of current trainees indicated satisfaction with their decision to train in psychiatry and over 90% intended to practise in New Zealand in the future. Most trainees who left training prematurely did so during the first 2 years of training. Dissatisfaction with work conditions, and stress or burnout were the main reasons for leaving. CONCLUSIONS: This study provides information on some of the complex determinants of psychiatric recruitment and retention in the New Zealand setting. Areas that could be addressed in order to improve recruitment, work satisfaction and retention in training are considered.

Adult↗
PubMed2000

Hearing by eye: how much spatial degradation can be tolerated?

In the McGurk effect (McGurk and MacDonald, 1976 Nature 264 746-748), illusory auditory perception is produced if the visual information from lip movements is discrepant from the auditory information from the voice. A study is reported of the tolerance of the effect to varying levels of spatial degradation (videotaped images of a speaker's face were quantised by a mosaic transform). The illusory effect systematically decreased with an increase in the coarseness of the spatial quantisation. However, even with the coarsest level (11.2 pixels/face) the illusion did not completely disappear. In addition, those participants who did not experience the illusion nevertheless showed the effects of auditory-visual interaction in their clarity ratings of the auditory stimulus. It is concluded that auditory-visual interaction in visible speech perception is based on relatively coarse-spatial-scale information.

Adolescent↗
PubMed2000

Medical complications after stroke: a multicenter study.

BACKGROUND AND PURPOSE: This prospective, multicenter study was performed to determine the frequency of symptomatic complications up to 30 months after stroke using prespecified definitions of complications. METHODS: We recruited 311 consecutive stroke patients admitted to hospital. Research nurses reviewed their progress on a weekly basis until hospital discharge and again at 6, 18, and 30 months after stroke. RESULTS: Complications during hospital admission were recorded in 265 (85%) of stroke patients. Specific complications were as follows: neurological-recurrent stroke (9% of patients), epileptic seizure (3%); infections-urinary tract infection (24%), chest infection (22%), others (19%); mobility related-falls (25%), falls with serious injury (5%), pressure sores (21%); thromboembolism-deep venous thrombosis (2%), pulmonary embolism (1%); pain-shoulder pain (9%), other pain (34%); and psychological-depression (16%), anxiety (14%), emotionalism (12%), and confusion (56%). During follow-up, infections, falls, "blackouts, " pain, and symptoms of depression and anxiety remained common. Complications were observed across all 3 hospital sites, and their frequency was related to patient dependency and duration after stroke. CONCLUSIONS: Our prospective cohort study has confirmed that poststroke complications, particularly infections and falls, are common. However, we have also identified complications relating to pain and cognitive or affective symptoms that are potentially preventable and may previously have been underestimated.

Accidental Falls↗
PubMed2000

Using telephone prompts to improve initial attendance at a community mental health center.

Contacting patients by telephone before their appointment has been shown to increase clinic attendance in various settings. However, no such studies have been conducted in New Zealand, which has a unique mix of publicly funded secondary care and largely privately funded primary care. A controlled prospective study of telephone prompting was carried out in a New Zealand publicly funded community mental health center. One group of 190 patients was phoned the day before their initial appointment, and their attendance rate was compared with that of 496 patients not phoned. Ninety-six percent of the patients who were successfully contacted kept their appointment, compared with 76 percent of those not contacted.

Adolescent↗
PubMed1999

Did Wellington have too many acute psychiatric beds in 1996?

AIMS: (1) To establish whether, as believed by local clinicians, there is a shortage of acute psychiatric beds available in Wellington. (2) To compare the current situation with that of seven years ago, before the beginning of the reduction in bed numbers, as a part of deinstitutionalisation and care in the community. (3) To study the effect on occupancy of changing availability. METHOD: Data were obtained retrospectively for the calendar years 1996 and 1989. These were examined using an analysis of variance and the results of the two years were compared. RESULTS: There were 214 days in 1996 when there were no acute psychiatric beds available. The mean daily occupancy was 100%. Comparing like populations, there was a highly significant increase in the mean occupancy as the availability decreased from 1989 to 1996. Conversely, there was a decrease in occupancy as availability temporarily increased during 1996. CONCLUSION: The number of acute psychiatric beds available in Wellington in 1996 was insufficient to meet the needs of the population, given the alternative resources available at that time. This is of particular concern in light of proposals to reduce the number of beds further.

Analysis of Variance↗
PubMed1999

Calcium-PS-dependent protein kinase C and surfactant protein A in isolated fetal rabbit type II alveolar cells and surfactant-related material.

The fetal lung secretes significant quantities of surfactant during late gestation to prepare for initiation of respiration at birth. However, the mechanism by which this occurs has not been determined. Since Ca2+-phosphatidylserine (PS)-dependent protein kinase C has been implicated in surfactant secretion in adult lung, the present study was done to determine whether this enzyme is also involved in the initiation of surfactant release from fetal type II cells. Type II cells isolated from gestational day-24 fetal rabbits were used. Cells were prelabelled with [32P] and [3H]choline and exposed to 4beta phorbol ester (10(-5) M) for 2 h. Secretion product and subcellular fractions were isolated by removing the culture medium, mixing with homogenate from adult rabbit lung, and subfractionating by centrifugation on a sucrose gradient. Samples of secretion product were also prepared for electron microscopy. Ca2+-PS-dependent protein kinase C was also assayed in some samples, and an add-back technique was used to determine whether enzyme activity in the intracellularly stored surfactant fraction was due to contamination. The results showed that material released by fetal type II cells after exposure to phorbol ester coprecipitated with adult rabbit lung lamellar bodies and microsomes. Morphologically, a range of forms, including lamellar-body-like structures, was detected. The released material originated largely from the lamellar body compartment of the fetal type II cells and displayed immunoreactivity with antibody to surfactant protein A (SP-A) at 35 and 70 kDa apparent molecular mass. Assay of protein kinase C in fetal type II cells showed that exposure to conditioned medium, which induces differentiation, increased activity. Incubation with phorbol ester induced translocation of activity to the microsomal fraction. Add-back assays suggested that protein kinase C activation by treatment with phorbol ester induced translocation of enzyme activity to the lamellar body fraction; none was detected prior to treatment. These results support a role for Ca2+-PS-dependent protein kinase C in initiation of surfactant release by interaction with the developing lamellar body compartment in fetal type II cells.

Animals↗
PubMed1999

Sample collection and clinical pathology of reptiles.

Clinical pathology techniques can guide the clinician to diagnose and treat the reptile patient successfully. Text, tables, pictures, and diagrams in this article describe blood and cytology collection techniques and interpretation for the common pet reptile species.

Animals↗
PubMed1999

Compositional analysis of glyphosate-tolerant soybeans treated with glyphosate.

The compositional analyses and safety assessment of glyphosate-tolerant soybeans (GTS) were previously described. These analyses were extensive and included addressing the potential effects on seed composition from the genetic modification. Detailed compositional analyses established that GTS, which had not been treated with glyphosate, were comparable to the parental soybean line and to other conventional soybeans. In this study, two GTS lines, 40-3-2 and 61-67-1, were treated with commercial levels of glyphosate, the active ingredient in Roundup herbicide. The composition of the seed from soybeans sprayed with glyphosate was compared to that of a nonsprayed parental control cultivar, A5403. The nutrients measured in the seed included protein, oil, ash, fiber, carbohydrates, and amino acids. The concentration of isoflavones (also referred to as phytoestrogens) was also measured as these compounds are derived from the same biochemical pathway that was engineered for glyphosate tolerance. The analytical results from these studies demonstrate that the GTS soybeans treated with glyphosate were comparable to the parental soybean cultivar, A5403, and other conventional soybean varieties.

Amino Acids↗
PubMed1999

The relation of p53 gene mutations to gastric cancer subsite and phenotype.

OBJECTIVES: We investigated p53 gene mutations in advanced gastric cancers by direct DNA sequencing, in order to determine the frequency of mutations in gastric cancers having different epidemiological backgrounds, tumors of the cardia were compared with those arising in the antrum or corpus. Intestinal type cancers were compared with diffuse or other histologic types. We have chosen to assess the frequency of mutations solely based on DNA sequencing. METHODS: Paraffin embedded tissues from 100 gastric cancers were evaluated. The mutational status of the p53 gene in exons 5 through 9 were determined by direct sequencing of PCR products. RESULTS: Mutations in exons 5, 6, 7 and 8 were found in 35 of 100(35%)stomach cancers. One tumor had mutations in both exons 5 and 8. No mutations were detected in exon 9. p53 gene mutations were significantly more frequent in cancers of the cardia (19/35; 54%) than the antrum and corpus (16/65 (25%)) (p < or = 0.005). p53 mutations were more frequent in intestinal type cancers (28/67; 42%) than diffuse cancers or other histologic types of cancer (7/33; 21%), but the difference was not statistically significant. CONCLUSIONS: Cancers of the cardia more frequently contain p53 mutations than do antral and corpus cancers, suggesting that cancers in the proximal and distal stomach evolve through different molecular pathways.

Base Sequence↗
PubMed1999

The effects of exercise intensity on post exercise hypotension.

Ten normotensive, recreationally active participants aged 35.0 +/- 16.3 years, volunteered to participate in the study. Average baseline blood pressure (BP) was 132/75 mm Hg for systolic (SBP) and diastolic (DBP) pressure respectively. On two separate days, participants underwent testing in a randomised, repeated measures fashion such that they performed 30-min bouts of cycle ergometry at a power output which elicited 50 or 75% of VO2 Peak. Blood pressure was monitored continuously throughout the session by the Finapres method with 2-min windows recorded at rest, 5, 10, 15, 30, 45 and 60 min post exercise. SBP was similar between the two trials and became hypotensive at 5 through 15 min post exercise. The largest decrement (8 mm Hg) in SBP occurred 5 min post exercise. DBP was also unaffected by the intensity of exercise and was lower than before exercise at 5 and 15 through 45 min post exercise. Similarly, mean arterial pressure (MAP) showed significant decrements at 5 and 15 through 45 min post exercise irrespective of exercise intensity. Heart rate was greater during the 75% intensity than during the 50% intensity trial. Pre-exercise values were re-established by 45 min post exercise. VO2 remained significantly elevated above pre-exercise values in both trials until 15 min post exercise. Haematocrit increased significantly during both exercise bouts but returned to pre-exercise values by 10 min post exercise. This study indicates that cycle ergometry at 50 and 75% of VO2 Peak elicit similar reductions in post exercise BP. Therefore bouts of mild to moderate intensity exercise may be beneficial in the control of hypertension.

Adult↗