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Biomedical subjects

A Lam

Publications and source records attributed to A Lam.

At least 19 recordsLinked to original sources
PubMed1998

Peptides derived from the complementarity-determining regions of anti-Mac-1 antibodies block intercellular adhesion molecule-1 interaction with Mac-1.

Peptides or small molecules that can block the interaction of the integrin Mac-1 with its receptor, intercellular adhesion molecule-1 (ICAM-1), have not previously been developed. We studied this interaction by measuring the adherence of ICAM-1-expressing Chinese hamster ovary (CHO) cells to immobilized, purified Mac-1. Nucleotide sequence information was obtained for the complementarity determining regions (CDRs) of three antibodies (44aacb, MY904, and 118.1) shown to block Mac-1-mediated cell adherence. Peptides were synthesized based on the predicted amino acid sequences of the CDRs and tested for the ability to block cell adhesion to Mac-1. Peptides derived from CDR1 of 44aacb, CDR2 of 118.1, and CDRs 1 and 3 of MY904 heavy chains were found to possess blocking activity at 10-100 muM. This may indicate that one or two CDRs contribute disproportionately to the antibody binding affinity. The binding of ligands to Mac-1 has been shown to require a region of the alpha-chain known as the I- or A-domain. We have recombinantly produced Mac-1 I-domain, and show that it is also capable of supporting the adherence of ICAM-1-expressing CHO cells. The adherence of ICAM-1-CHO cells to the I-domain is inhibited by 44aacb and 118.1 and by the CDR peptides from 44aacb and 118.1. By using phage display of peptide libraries based on the 118.1 CDR peptide with five residues randomized, we were able to identify a novel peptide inhibitor of Mac-1 with substitutions at all five positions. These peptides provide lead structures for development of Mac-1 antagonists.

Amino Acid Sequence↗
PubMed1998

Myogenic nitric oxide synthase activity in canine lower oesophageal sphincter: morphological and functional evidence.

1. Studies on canine lower oesophageal sphincter (LOS) evaluated the existence and function of a myogenic, nitric oxide synthase (NOS) by use of immunocytochemistry for NOS isozymes, NADPH-d histochemistry, [3H]-L-arginine to [3H]-L-citrulline transformation. In addition, functional studies in the muscle bath were performed. 2. Smooth muscle bundles or freshly isolated smooth muscle cells of LOS were NADPH-d reactive but did not recognize some antibodies against neural, endothelial or inducible NOS. NADPH-d reactivity and immunoreactivity to a neural NOS antibody were colocalized in LOS enteric nerves. Muscle plasma membrane-enriched fractions from fresh and cultured LOS cells converted [3H]-L-arginine to [3H]-L-citrulline; activity was mostly Ca2+/calmodulin-dependent. 3. N-Nitro-L-arginine (L-NOARG) persistently increased tone (blocked by L-arginine) in muscle strips despite blockade of nerve function. Nifedipine prevented or abolished L-NOARG-induced, but not carbachol-induced, contraction showing that tone increase by L-NOARG required functional L-Ca channels. 4. Membrane-bound, myogenic NOS in canine LOS may release NO continuously when Ca2+ entry through L-Ca channels occurs under physiological conditions and thereby modulate tone in LOS.

Animals↗
PubMed1998

Prediction of individual response to postnatal dexamethasone in ventilator dependent preterm infants.

AIMS: To evaluate factors predictive of individual response to dexamethasone in preterm infants. METHODS: A cohort of 74 preterm infants born between January 1993 and February 1996 was studied retrospectively. All of them had received dexamethasone to facilitate weaning from artificial ventilation. Demographic factors, ventilation parameters, and details of dexamethasone administration were recorded from the medical and nursing notes. Radiographs were assessed by one observer who was unaware of the clinical condition of the infant or the outcome. Outcome variables examined included change in ventilation index (VI) at 36-48 hours, the number of days to extubation from the start of dexamethasone, and death before extubation. RESULTS: Most babies improved but changes in VI at 36-48 hours ranged from substantial deterioration to dramatic improvement. No identifiable factors were significantly associated with this range of response. The median time to extubation was 6 days. The 36 babies who extubated within the first 6 days were: significantly more mature; less likely to have pulmonary interstitial emphysema (PIE) or pneumothorax; and had significantly lower VIs in the 12 hours preceding dexamethasone treatment. The postconceptional age at extubation was the same whether babies were extubated within or after the first 6 days. Multiple linear regression confirmed a significant association between number of days to extubation and the three factors described above (adjusted R2 = 0.5126). CONCLUSIONS: Individual responses to dexamethasone can be partly predicted by gestation, the presence of PIE, and the VI before dexamethasone administration.

Dexamethasone↗
PubMed1998

Chinese herbal medicine and acupuncture. How do patients who consult family physicians use these therapies?

OBJECTIVE: To determine how a population of Chinese patients consulting family physicians in Vancouver use traditional Chinese medicine (TCM), specifically Chinese herbal medicine and acupuncture. DESIGN: Bilingual survey (English and Chinese). SETTING: Four family practices with predominantly Chinese patients in metropolitan Vancouver. PARTICIPANTS: The 932 patients or family members who visited one of the practices. MAIN OUTCOME MEASURES: Demographic characteristics; frequency and reason for visiting a family physician, Chinese herbalist, or acupuncturist; choice of practitioner if affected by one of 16 common conditions. RESULTS: The study population was mostly Chinese and immigrant to Canada. Chinese herbal medicine was currently used by 28% (262/930) of respondents (more than one visit in the last year), and another 18% (172/930) were past users. Acupuncture was currently used by 7% (64/927) and had been used in the past by another 8% (71/927). Use of Chinese herbal medicine varied significantly (P < .01) according to age, sex, immigrant status, and ethnicity. Acupuncture use varied significantly only by age. The main reasons for consulting Chinese herbalists were infection (41%, 157/382), respiratory problems (11%, 42/382), and rheumatologic problems (10%, 38/382), whereas acupuncturists were consulted almost exclusively for rheumatologic problems (80%, 45/56). CONCLUSIONS: Using TCM in conjunction with visiting family physicians was very popular among this predominantly Chinese study population. Patients with acute conditions, such as influenza, consulted both their family physicians and Chinese herbalists in quick succession. On the other hand, those suffering from more chronic conditions, such as rheumatologic diseases, were more likely to start using TCM after repeated visits to their family physicians.

Acupuncture Therapy↗
PubMed1998

Calcium source diversity in canine lower esophageal sphincter muscle.

Tonic contraction of the lower esophageal sphincter (LES) prevents gastroesophageal reflux. LES tone is produced both by cholinergic nerve and myogenic activities. The Ca++ sources for LES tone and carbachol-induced contraction in canine LES strips were determined from the effect on contractile activity of extracellular Ca++ level modulation, Ca++ entrance blockade or enhancement with nifedipine or BayK8644 respectively, and/or inhibition of Ca++ store refilling using the sarcoplasmic reticulum Ca++ pump inhibitor, cyclopiazonic acid. LES tone disappeared when a Ca++-free physiological saline solution or nifedipine was applied. Sustained Ca++ free contractions to carbachol were prevented/abolished by nifedipine or increased Ca++ chelation and enhanced by BayK8644. Inhibition of sarcoplasmic reticulum Ca++ pumps by cyclopiazonic acid reduced Ca++ free contractions to carbachol; BayK8644 restored cyclopiazonic acid-reduced Ca++ free contractions to carbachol. Therefore, some Ca++ stores can be refilled by mechanisms not requiring activity of the sarcoplasmic reticulum Ca++ pump. A preferred pathway may exist whereby Ca++ enters stores directly through L-Ca++ channels. The proposed Ca++ store refilling mechanism involves continuous Ca++ entry through L-Ca++ channels from sites not equilibrated with external Ca++. Therefore, diverse Ca++ stores exist in canine LES which are dependent on Ca++ influx through L-Ca++ channels.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1998

Tear break-up time: clinical procedures and their effects.

Three successive (representative) values of fluorescein-instillation TBUT (tear break-up time) were obtained from a group of young Hong Kong (HK)-Chinese. The median TBUT1, TBUT2 and TBUT3 were 3.2, 3.8 and 4.5 sec, respectively. Wilcoxon signed-rank tests showed that TBUT1 was significantly different from TBUT2 and TBUT3, but there was no difference between TBUT2 and TBUT3. It is therefore important, when measuring the TBUT, to specify which TBUT value was taken as the representative TBUT. Fluorescein was reapplied about six min after the first application, and the TBUT value re-determined (TBUTR). The median TBUTR was not significantly different from TBUT1. The subjects were requested to return another day and TBUT values (TBUTW) were determined, with the subjects opening their eyes as wide as possible, such that the palpebral aperture size was increased. The mean +/- SD normal palpebral aperture size was 10.0 +/- 1.3 mm, and the mean +/- SD palpebral aperture size with the eyes wide open was 11.4 +/- 1.5 mm. The median TBUTW (3.6 sec) was significantly longer than the median TBUT1 (3.0 sec), but this difference appeared to be due to the extremely long TBUTW of one subject; no significant difference was found between the median TBUTW (3.4 sec) and TBUT1 (2.8 sec) when data from this subject were excluded. There was no significant correlation between changes in palpebral size and TBUT value.

Adult↗
PubMed1997

Laparoscopic colposuspension. Is it cost-effective?

BACKGROUND: The laparoscopic approach must be shown to be cost-effective as well as safe and technically effective before being widely adopted. A review of 54 consecutive patients who underwent open and laparoscopic colposuspension is presented and a cost-analysis is performed comparing the two approaches. METHODS: This study was a retrospective controlled review of patient records and accounts of in-hospital costs incurred at a private hospital. RESULTS: Theater costs were significantly greater in the laparoscopic group but this was balanced by a shorter length of stay and subsequent reduced accommodation cost. There was no difference in the overall in-hospital costs between the two groups. CONCLUSION: The laparoscopic surgical approach is safe and effective and by no means more expensive than the open approach. In the future, the laparoscopic approach can only become more cost efficient; techniques will improve and there will be earlier returns to work and, subsequently, greater productivity.

Adult↗
PubMed1997

Variation in the diagnosis of vesicoureteric reflux using micturating cystourethrography.

Variability in the interpretation of micturating cystourethrography by paediatric radiologists for the diagnosis of vesicoureteric reflux in children was evaluated. All 265 micturating cystourethrograms (MCUs) that were available from 304 consecutive children aged 0.5-61 months-who were investigated after their first urine infection between 1993 and 1995 as part of a prospective cohort study-were selected for interpretation. Three experienced paediatric radiologists from the same department independently interpreted the MCUs according to the grading system of the International Reflux Study in Children, from grades 0 to V, with the presence of intrarenal reflux also noted. Apart from being informed that urine infection was the indication for the MCU, no other clinical information was given to the radiologists. The indices of variability used were the percentage of agreement and the kappa statistic, expressed as a percentage. Both measures were weighted with integers representing the number of categories from perfect agreement. Disagreement was analysed for children and kidneys. For the diagnosis of vesicoureteric reflux in individual patients, including grade, the percentage of agreement was 96%-97% (kappa 90%-91%) and the weighted percentage of agreement was 96%-98% (weighted kappa 93%-94%). The same high level of agreement was present for individual kidneys, with a percentage of agreement of 97%-98% (kappa 89%-92%) and a weighted percentage of agreement of 98%-99% (kappa 94%-95%). There was near perfect agreement in the interpretation of radiological micturating cystourethrography among three experienced paediatric radiologists for the diagnosis and grade of vesicoureteric reflux. Any variations in the medical care of children suspected of having vesicoureteric reflux are not explained by differences in the reporting of this diagnostic test.

Child↗
PubMed1997

Laparoscopic colposuspension in women with previously failed anti-incontinence surgery.

OBJECTIVES: To assess the effectiveness of laparoscopic colposuspension after previously failed anti-incontinence surgery. METHODS: Retrospective review of 10 cases, all with urodynamically proven grade 2 genuine stress incontinence. RESULTS: All patients were subjectively cured at 3 months or more follow-up. The mean hospital stay was 2.9 days, the mean time until normal voiding was 1.7 days, and the mean blood loss was 39 ml. CONCLUSION: Laparoscopic colposuspension may be useful after failed anti-incontinence surgery. However, larger numbers are needed with objective longer term follow-up.

Adult↗
PubMed1997

Vesicoureteric reflux and timing of micturating cystourethrography after urinary tract infection.

OBJECTIVE: To test the medical belief that the micturating cystourethrogram (MCU) be deferred four to six weeks after acute symptomatic urinary tract infection (UTI) because of the risk of falsely detecting vesicoureteric reflux if performed earlier. STUDY DESIGN: A cross sectional analytic study of preschool children with first time symptomatic UTI. RESULTS: Of the 284 eligible children, 272 (95.8%) had MCU at a median time of 29 days after diagnosis (range 5 to 167 days). Vesicoureteric reflux was present in 77 children (28.3%). Beyond one week after diagnosis (270 children) the proportion and severity of vesicoureteric reflux detected was not associated with the timing of the MCU. Before one week, both children tested had vesicoureteric reflux. CONCLUSIONS: The presence and grade of vesicoureteric reflux is not influenced by the timing of the MCU one week after acute symptomatic UTI. There may be an association between the MCU and the presence of vesicoureteric reflux for children tested within one week after UTI. The MCU need not be deferred for four to six weeks after UTI.

Child, Preschool↗
PubMed1996

Laparoscopic Bowel and Vascular Complications: Should the Veress Needle and Cannula Be Replaced?

We undertook a retrospective survey of bowel and vascular complications in gynecologic laparoscopic surgery reported to the three major medical defense organizations in this state between January 1988 and September 1993. Twenty-six bowel injuries and eight vascular complications were reported. The majority of these patients had undergone either diagnostic laparoscopy or laparoscopic tubal ligation. The majority of injuries were attributed to the Veress needle in creating primary pneumoperitoneum or inserting the primary cannula. Three of the 26 bowel injuries and 3 of 8 vascular injuries resulted in death. Laparoscopic bowel and vascular injuries can thus be related to the Veress needle or the primary cannula. The serious sequelae suggest a need to assess the current methods of establishing pneumoperitoneum for laparoscopy.

Journal Article↗
PubMed1996

Complications of 174 laparoscopic hysterectomies.

The case records of 174 patients who underwent laparoscopic hysterectomy between September, 1992 and April, 1995 were retrospectively reviewed. The mean age of the group was 45.4 (range 17.8-68.5) years, mean weight 70.2 (50-121) kg and mean parity 2.3 (0-4). Laparoscopic hysterectomy (i.e. uterine arteries secured laparoscopically) was performed in 98 patients, laparoscopically assisted vaginal hysterectomy in 70, and laparoscopic subtotal hysterectomy in 6. Bilateral or unilateral oophorectomy were performed in 40 cases. The mean operating time was 131 (45-285) minutes and mean hospitalization 2.6 (1-11) days. Endoscopic stapling devices were used in 135 cases, biopolar diathermy in 117, sutures and ties in 84, and the harmonic scalpel in 29. The overall complication rate was 16%. Seven cases (4%) required conversion to laparotomy. These included 2 inadvertent cystotomies (1 after 2 Caesarean sections), 3 cases of dense uterovesical adhesions following previous surgery and 2 instances of excessive uterine size (> 16 weeks). The mean follow-up period was 2.2 (1-18) months. One patient had a shortened vagina requiring dilatation and another had vault granulations requiring diathermy treatment. Overall 98.3% of patients were satisfied with their surgery.

Adolescent↗
PubMed1996

A review of results in a series of 113 laparoscopic colposuspensions.

The case records of 113 women having laparoscopic retropubic colposuspensions (Burch procedure) performed for the treatment of genuine urinary stress incontinence between December, 1992 and April, 1995 were retrospectively reviewed. The mean age of the group was 49.4 (30-80) years, mean weight 72.1 (44.5-114) kg, and mean parity 2.7 (0-8). All patients had preoperative urodynamic study to confirm genuine stress incontinence (GSI). Sixteen patients (14%) had dual pathology (GSI and detrusor instability). A transperitoneal approach was used in 93 operations and extraperitoneal in 20. The mean operating time was 108 (30-320) minutes and mean hospitalization 3.3 (1-10) days. In 13 women the operation was converted to laparotomy; 10 due to adhesions and diminished bladder mobility, 1 for inferior epigastric vessel injury, 1 for an ovarian tumour discovered incidentally at the procedure and 1 for equipment problems. Operative complications included 10 cystotomies (5 repaired laparoscopically), 2 extraperitoneal cases converted to transperitoneal, 1 inferior epigastric vessel injury, 1 vaginal tear, 1 suture through the bladder and 1 case of possible enterotomy oversewn at laparoscopy. The mean follow-up period was 8.4 (1-28) months. All patients were reviewed postoperatively and then contact was attempted either by telephone or in consultation. There was an overall 87% subjective success rate. Two patients felt sutures tear out at 4 and 6 months and were deemed failures; 4 felt their incontinence was improved but had ongoing stress incontinence of urine; 9 had symptoms of detrusor instability and one developed an enterocele 9 months after surgery.

Adult↗
PubMed1996

[A familial form of epidermoid carcinoma of the conjunctiva].

Two two-sided cases of conjunctival epidermoid carcinoma and one dysplasia in the same family are reported. The three sisters concerned were teenagers. This familial disease with bilateral localizations in young female patients, is quite rare. Clinical, histological and epidemiological conclusions were based on familial investigation.

Adolescent↗
PubMed1996

[Spontaneous and bilateral anterior luxation of the lens in a 5-year-old child].

The authors report a case of bilateral spontaneous dislocation of the lens in a five-year-old boy. This rare complication can be encountered in certain congenital abnormalities of the lens and zonule. The dislocation has been revealed by an acute glaucoma. The mains causes like Marfan's syndrome and homocystinuria were not found but due to their most severe prognosis. The patient must be followed carefully.

Acute Disease↗
PubMed1996

[Non-sarcomatous bilateral exophthalmos disclosing acute myeloblastic leukemia in children].

The authors report a bilateral exophthalmos due to a leukemic infiltration of the orbital lacrimal glands during an acute myeloblastic leukemia in a ten-year-old boy. This rare orbital localization revealed the leukemia. It was not a granulocytic sarcoma. Its importance leads to the extraction of the lacrimal glands in order to prevent the eyes from corneal perforation.

Child↗