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Biomedical subjects

C Lam

Publications and source records attributed to C Lam.

At least 37 records · Page 2Linked to original sources
PubMed1998

Sonographic localization of abdominal vessels in Chinese women: its role in laparoscopic surgery.

Trauma to abdominal wall blood vessels occurs following 0.2-2% of laparoscopic operations. This prospective observational study assessed the possible role of sonographic localization of abdominal blood vessels prior to laparoscopic surgery in Chinese women and compared the findings reported in a Western group. The inferior epigastric and superficial circumflex iliac vessels were located by color Doppler imaging. Ultrasonography was 100% and 80% successful in locating the inferior epigastric and the superficial circumflex iliac vessels, respectively. The positions of the inferior epigastric vessels were similar to those reported in the Western population whilst the superficial circumflex iliac vessels were found to be situated 1 cm more medially. In our study population, a safe area for entry of lateral ports appeared to be 7 cm from the midline and 5 cm above the pubic symphysis. Sonographic localization of abdominal blood vessels is a potentially useful clinical tool in the prevention of blood vessel trauma.

Adult↗
PubMed1998

Cyclic nucleotide phosphodiesterase 4 subtypes are differentially expressed by primary keratinocytes and human epidermoid cell lines.

Cyclic AMP phosphodiesterase (PDE) type 4 has been the subject of considerable interest as a potential molecular target for treating cutaneous inflammatory and allergic disorders; however, little is known regarding the expression of PDE 4 isogenes in human keratinocytes, the predominant cell type present in the epidermis. In this study, we investigated the expression of PDE 4 subtypes in epidermal cells (primary keratinocytes derived from breast skin, epidermoid cell lines A431, KB, and HaCaT) using reverse transcriptase polymerase chain reaction. Analysis of the amplified cDNA showed that there were differences in the expression of PDE 4 isogenes in the epidermal cells. Constitutive expression of the PDE 4 isozymes was detected in untreated epidermal cells at different levels. Transcripts for PDE 4B and 4D were abundantly expressed in breast skin-derived keratinocytes, whereas transcripts for PDE 4A, 4C, and 4D were present in HaCaT cells and transcripts for all the PDE 4 isotypes were present in A431 and KB. PDE 4A and 4C were detectable in HaCaT cells in equal amounts, but PDE 4C was only marginally expressed in the other cells. Of the four isogenes, PDE 4D was abundantly expressed in all the cells. Elevation of intracellular levels of cAMP by forskolin increased the expression of all the hPDE 4 isogenes 2-3-fold as revealed by semiquantitative reverse transcriptase polymerase chain reaction. Western blot analysis of extracts from control and forskolin or dibutyryl cAMP-treated A431 and KB cells demonstrated the presence of proteins with a molecular mass identical to that corresponding to recombinant human PDE 4B. Together, these findings show that PDE 4 isogenes are expressed in keratinocytes to a different degree and that their expression can be modulated by intracellular levels of cAMP.

Blotting, Western↗
PubMed1998

MDP(Lysyl)GDP, a nontoxic muramyl dipeptide derivative, inhibits cytokine production by activated macrophages and protects mice from phorbol ester- and oxazolone-induced inflammation.

High levels of pro-inflammatory cytokines and nitric oxide are proposed to orchestrate pathophysiologic mechanism(s) associated with various inflammatory dermatoses. This study examines whether a water soluble 3-O-[N-acetylmuramyl-L-lysyl-D-iso]-2-di-on-glycine [MDP(Lysyl)GDP], a nontoxic and nonpyrogenic derivative of muramyl dipeptide (MDP), can inhibit the in vitro production of inflammatory mediators by lipopolysaccharide- or interferon-gamma-activated macrophages, and whether such an inhibitory effect can translate into in vivo protection of mice from irritant and allergic contact dermatitis. Thioglycollate-elicited peritoneal macrophages cultured in medium alone or in medium supplemented with MDP(Lysyl)GDP (1-100 microg per ml) expressed neither mRNA transcripts for inducible nitric oxide synthase, interleukin-1beta, and tumor necrosis factor-alpha, nor cytokine proteins and nitric oxide activity. Incubation of the cells with either lipopolysaccharide or interferon-gamma for 6 h resulted in a significant induction of inducible nitric oxide synthase, interleukin-1beta, and tumor necrosis factor-alpha mRNA, and the accumulation of high levels of monokines and nitrites in cultures by 24 h. Co-incubation of the macrophages with lipopolysaccharide or interferon-gamma and MDP(Lysyl)GDP (1-100 microg per ml) resulted in a concentration-dependent suppression of the steady-state mRNA transcripts for inducible nitric oxide synthase, tumor necrosis factor-alpha, and interleukin-1beta, induced by lipopolysaccharide, but not by interferon-gamma. In mouse models of phorbol ester- and oxazolone-induced ear inflammation, topical application of MDP(Lysyl)GDP significantly suppressed ear swelling in a dose-dependent manner. Likewise, oral treatment with MDP(Lysyl)GDP at days -3, -2, and -1 before elicitation with oxazolone also significantly inhibited ear inflammation. Taken together, our findings suggest that MDP(Lysyl)GDP has the potential to be a therapeutic application in the treatment of inflammatory conditions in which overproduction of pro-inflammatory mediators are implicated to play a pathogenic role.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1998

Sonographic evaluation of the myomectomy 'scars'.

BACKGROUND: The evolution of myomectomy 'scars' has not been reported. This prospective study was carried out to determine the evolution of the myomectomy 'scars' following conventional open myomectomy. METHODS: Ten patients admitted for myomectomy were recruited. The sizes of the leiomyomata were determined with ultrasonography. Serial sonographic examinations were performed following the open myomectomy so as to determine the morphology and volume of the scars. The volumes of the uterus were also measured to document the postoperative remodeling of the uterus. RESULTS: The myomectomy 'scars' were represented by an area with mixed echogenic echoes in the immediate postoperative period. In one month, their volumes decreased to less than 5% of the preoperative volumes and were reduced to vague areas marked by short echogenic lines at 6 months. Most of the remodeling of the uterus occurred in the first month postoperatively. CONCLUSIONS: The mixed echogenic areas probably represented the approximated myometrial walls of the leiomyomata. Detection of such in postoperative sonography should not cause undue alarm.

Adult↗
PubMed1997

Transcytosis and surface presentation of IL-8 by venular endothelial cells.

Chemokines have been convincingly implicated in actuating inflammatory leukocyte emigration. To affect the circulating leukocytes, tissue-derived chemokines have to traverse the endothelial cells (ECs). This was thought to be accomplished by chemokine diffusion through the intercellular gaps. On the contrary, we show by electron microscopy that the prototype chemokine IL-8 is internalized by venular ECs abluminally and transcytosed to the luminal surface. Here, it is presented to the adherent leukocytes on the EC membrane, predominantly in association with the EC projections. The intact C terminus of IL-8, the molecule's "immobilization" domain, is required for the EC binding, transcytosis, and consequently, the in vivo proemigratory activity of IL-8, indicating that the described subcellular interactions of IL-8 with the ECs are functionally relevant.

Animals↗
PubMed1997

Childhood intussusception: ultrasound-guided Hartmann's solution hydrostatic reduction or barium enema reduction?

A comparison was made of the efficacy of ultrasound guided Hartmann's solution hydrostatic reduction on 23 patients (US group) with the same number of consecutive patients in whom hydrostatic reduction was done by barium enema (BE group) under fluoroscopy for childhood intussusception. The US group was diagnosed by ultrasound scan and reduction was attempted under the guidance of ultrasonography with Hartmann's solution at 100 mm Hg pressure. Excluded were patients older than 12 years, patients in shock, patients with peritonitis, bowel perforation, and gross abdominal distension as well as recurrent intussusception of more than three episodes. There were three patients excluded in this group. The diagnosis of intussusception and complete reduction were confirmed by gastrografin enema. This US group had three recurrences (3 of 26, 11.5%), one lead point (1 of 23, 4.4%), and 19 successful reductions (19 of 26, 73%). Incidentally, there were also three patients excluded in this period of barium enema reduction. There was only one recurrence (1 of 24, 4.2%), one leadpoint (1 of 23, 4.4%), and 12 successful reductions (12 of 24, 50%) in these 23 BE patients. The success rates for the ileo-colic intussusceptions with Hartmann's solution reduction and barium enema reduction were 91% (19 of 21) and 55% (12 of 22), respectively (P = .00865). There was no complication in either group, and the accuracy of diagnosing a complete reduction was 100% in both forms of reduction. Hence, ultrasound-guided hydrostatic reduction for childhood ileocolic intussusception is preferred because it is safe, accurate, has a higher success rate, and can avoid radiation exposure risk.

Barium Sulfate↗
PubMed1997

How mental health and developmental disabilities staff prioritize training and development needs.

This paper contrasts a staff training needs assessment distributed to three groups: staff serving persons with mental health needs in the community, staff serving persons with mental health needs in state hospitals, and staff serving persons with developmental disabilities in the community. Analyses revealed that all three groups rated team-related training as the area in greatest need of development. Further analyses suggested that community staff serving persons with developmental disabilities reported significantly less need for training on direct client care compared to community and inpatient staff who serve persons with mental health needs. The community staff serving persons with mental health needs did not differ significantly from the inpatient staff on any of the surveyed training areas. Results suggest that future development efforts should begin with team building skills.

Adult↗
PubMed1997

Ileoileocolic intussusception in children: diagnosis and significance.

The ileoileocolic type of childhood intussusception is difficult to diagnose pre-operatively and is associated with increased morbidity. This study describes the clinical and imaging features of 10 consecutive ileoileocolic intussusceptions diagnosed ultrasonically in 10 patients over a 36 month period. Ultrasound-guided hydrostatic reduction using Hartmann's solution was attempted in all 10 patients. Clinical and imaging features were compared with those of 28 ileocolic intussusceptions in 25 patients diagnosed and treated using the same methods during the same period. Most of the clinical and plain radiographic features of the patients with the ileoileocolic and ileocolic types of intussusception were similar. The two types of intussusception had the classical doughnut or pseudokidney, or both, signs on pre-reduction ultrasound scans. During the reduction process, when surrounded by fluid within the caecal lumen, the ileoileocolic type of intussusception had a typical complex appearance due to frond-like loops of intussuscepted small bowel. This finding was present in all cases. The hydrostatic reduction rate was only 10% (1/10) for ileoileocolic intussusception, compared with 92.9% (26/28) for the ileocolic type. All unsuccessfully-reduced cases underwent surgery, with surgical confirmation of the intussusception type in all cases. Only one patient was found to have a lead point, caused by a Meckel's diverticulum. In conclusion, the diagnosis of ileoileocolic intussusception can be made pre-operatively and these patients require surgical management.

Child↗
PubMed1997

Phenotypic stability of a cytotoxic T-cell line directed against an immunodominant epitope of human carcinoembryonic antigen.

CTL lines have now been generated against defined peptides of a range of human tumor-associated antigens (TAAs). One of the potential uses of these epitope-specific CTLs is in adoptive transfer immunotherapy. This is a modality, however, that will require long-term in vitro culture of CTLs. To date, little has been reported concerning the phenotypic stability of human epitope-specific CTLs as a consequence of long-term in vitro propagation via peptide stimulation. We report here the serial phenotypic characterization of a CTL line directed against an immunodominant epitope (YLSGANLNL, designated CAP-1) of human carcinoembryonic antigen (CEA). This CTL line was derived from peripheral blood mononuclear cells of a patient with metastatic carcinoma who had been treated with a recombinant CEA-vaccinia vaccine in a Phase I trial; the CTLs were analyzed through 20 in vitro cycle passages of stimulation with CAP-1 peptide and interleukin 2 in the presence of autologous antigen-presenting cells. The CTL line was shown to be phenotypically stable in terms of high levels of cytokine (IFN-gamma, tumor necrosis factor, and granulocyte-macrophage colony-stimulating factor) production, expression of homing-adhesion molecules, ability to lyse peptide-pulsed targets, and ability to lyse human carcinoma cells endogenously expressing CEA in a MHC-restricted manner. Vbeta T-cell receptor gene usage was also analyzed. These studies thus present a rationale for the use of long-term cultured epitope-specific human CTLs, directed against a human TAA for potential adoptive transfer immunotherapy protocols.

Antigens, CD↗
PubMed1996

Decreased capillary density in vivo in bowel mucosa of rats with normotensive sepsis.

Translocation of bacteria and endotoxin leading to sepsis occurs in animals subjected to burns or intestinal ischemia. This may be mediated in part by bowel mucosal microcirculatory dysfunction. However, the direct effect of sepsis on the mucosal microcirculation is unknown. The objective of this study was to develop a technique for intravital microscopy of the mucosa of the small bowel in an animal model of normotensive sepsis. We tested the hypothesis that normotensive sepsis induced by cecal ligation and perforation leads to a decrease in perfused capillaries in the small bowel mucosa at 24 hr. Twelve male Sprague-Dawley rats were hemodynamically monitored and randomly assigned to cecal ligation and perforation (CLP) or control laparotomy (sham). Twenty-four hours after initial surgery each animal was reanesthetized and the mucosal surface of the distal small bowel prepared for intravital microscopy. Laser doppler measurements of bowel wall blood flow were made immediately and repeated after a 30-min stabilization period. Intravital microscopy of the mucosal microcirculation of six villi per animal was performed and the images recorded on videotape (2 min/villus). The areas surrounded by perfused capillaries (intercapillary area) were then measured using video analysis software. Laser doppler flowmetry revealed a decrease in bowel wall blood flow during the stabilization period in the shams that did not occur in the CLP rats. The intercapillary areas were significantly greater in the CLP rats compared to sham rats (1329 +/- 316 microns2 vs 979 +/- 217 microns2, P = 0.044). The intercapillary areas were also more highly variable in the CLP group (median coefficient of variation 102 vs 83% in the sham group, P = 0.025). Intravital microscopy may be used to examine microcirculatory function of the small bowel mucosa. Sepsis induced by CLP leads to a decrease in the number of perfused capillaries in the small bowel mucosa.

Animals↗
PubMed1996

Selective inhibition of interleukin-1 beta gene expression in activated RAW 264.7 macrophages by interferon-gamma.

The ability of interleukin-1 (IL-1) to activate epidermal cell populations supports its role as a key cytokine in the pathogenesis of a number of inflammatory skin diseases. In the present study, we have examined the effect of interferon (IFN)-gamma on the expression of the IL-1 beta gene in mouse RAW 264.7 macrophages activated by lipopolysaccharide (LPS) plus tumor necrosis factor (TNF)-alpha. Incubation of macrophages with both LPS and TNF-alpha resulted in the expression of both IL-1 beta and inducible nitric oxide synthase (iNOS) mRNA transcripts and increased the release of IL-1 beta protein and nitrite production in culture supernatants. Addition of IFN-gamma up-regulated the expression of the iNOS gene in cells activated by LPS + TNF-alpha, but significantly suppressed the induction of IL-1 beta gene expression in a dose-dependent manner. The suppression required neither de novo protein synthesis nor involved destabilization of the mRNA transcripts. Together, these findings suggest that IFN-gamma can be an important regulatory cytokine in a chronic inflammatory site and may explain its purported anti-inflammatory effects in certain dermatological diseases.

Animals↗
PubMed1996

Fetal cerebral Doppler studies as a predictor of perinatal outcome and subsequent neurologic handicap.

OBJECTIVE: To study the use of middle cerebral arterial Doppler findings in a group of high-risk fetuses as a predictor of adverse perinatal outcome, including subsequent neurologic handicap. METHODS: A group of very high-risk fetuses was recruited over a 2-year period for study. Weekly fetal biometries and Doppler studies of the umbilical artery and middle cerebral arteries were carried out until delivery. Main outcome indices analyzed included birth weight ratio (ratio of observed birth weight to mean birth weight for gestation), days of ventilator requirement, neonatal intracranial hemorrhage or periventricular leukomalacia, necrotizing enterocolitis, and follow-up data on major neurologic handicap and death. RESULTS: Seventy-four patients were recruited. One hundred thirty-four sets of examinations were made and prospective follow-up data were available for up to 2 years. The ratio of the umbilical and middle cerebral arterial resistance index was found to be inversely proportional to the birth weight ratio. Fetuses who had a high prenatal umbilical-cerebral Doppler ratio had significantly lower birth weight ratios than those with normal findings (0.72 versus 0.92; P < .001). The ratio was a more sensitive marker for growth restriction (sensitivity 78%) than conventional fetal biometry and umbilical arterial systolic-diastolic ratio. However, fetuses with high ratios did not have higher incidences of perinatal complications or subsequent neurologic handicap. CONCLUSION: Prenatal cerebral vasodilation is a sensitive marker for growth restriction and it seems to be a physiologic response to hypoxia. Fetuses with intrauterine cerebral vasodilation do not have increased risk for subsequent gross neurologic damage.

Adult↗
PubMed1996

The role of Doppler sonography in assessment of malignant trophoblastic disease.

An observational study on the role of Doppler sonography in the assessment of patients with malignant trophoblastic disease was performed in an Oncology Unit of a University teaching hospital. A total of 32 consecutive patients referred for chemotherapy were recruited. Twenty-three non-pregnant and 18 women in the first trimester of pregnancy acted as controls. The patients were prospectively followed-up for 2 years. It was found that the uterine arterial resistance index and pulsatility index in patients who required chemotherapy were significantly lower when compared with the non-pregnant and pregnant controls; (Student t-test; P < 0.001 and P < 0.01, respectively). Stepwise regression analysis of beta-hCG titres on uterine artery resistance index showed significant correlation, after controlling for uterine volume (adjusted multiple R = 0.71, P < 0.00001). There were, however, no significant independent associations between the initial uterine artery resistance index and the need for chemotherapy, number of courses of chemotherapy required, duration required for the beta-hCG titre to return to normal, presence of metastatic disease, or the subsequent development of drug resistance or relapse. It was concluded that uterine arterial Doppler indices are significantly correlated with trophoblastic activity (beta-hCG titres) in malignant trophoblastic disease. However, their role in the prediction of subsequent tumour behaviour need to be assessed in larger series.

Chorionic Gonadotropin, beta Subunit, Human↗
PubMed1996

Sonographically guided hydrostatic reduction of childhood intussusception using Hartmann's solution.

OBJECTIVE: Currently, the standard methods for therapeutic reduction of intussusception in children involve considerable ionizing radiation. This study tested the effectiveness of sonographically guided hydrostatic reduction of intussusception using Hartmann's solution, a fluid with near-physiologic composition. SUBJECTS AND METHODS: Between March 1, 1994, and January 31, 1996, all children clinically suspected of having intussusception were evaluated by sonography. Those with positive findings on sonography were entered into the study and underwent confirmatory sonographically guided meglumine diatrizoate enema. During continuous sonographic monitoring, we used Hartmann's solution for attempted reduction of intussusception. Criteria for successful reduction were disappearance of the intussusceptum and passage of fluid through the ileocecal valve. Another sonographically guided meglumine diatrizoate enema was used to confirm successful reduction. RESULTS: We detected 25 consecutive intussusceptions in 22 patients. The patients were 12 girls and 10 boys, with a mean age of 14 months (range, 1-72 months). Sonograms revealed in all patients doughnut or pseudokidney signs or both. The sites of intussusception were the transverse colon (17 of 25), hepatic flexure (4 of 25), ascending colon (2 of 25), splenic flexure (1 of 25), and descending colon (1 of 25). Other findings were dilated fluid-filled small bowel (11 of 25) and free intraperitoneal fluid (9 of 25). The success rate of our sonographically guided attempts at hydrostatic reduction was 76% (19 of 25). Success was proven by meglumine diatrizoate enema in all 19 patients. The mean time of the reduction procedure was 18 min (range, 2-45 min). No complications occurred. All six patients in whom hydrostatic reduction was unsuccessful underwent surgery. Five of these patients had ileoileocolic intussusceptions. On sonography, when surrounded by fluid, ileoileocolic intussusceptions had a typically complex, fronded appearance. The remaining patient in whom hydrostatic reduction was unsuccessful had ileocolic intussusception. Of six ileoileocolic intussusceptions, one was hydrostatically reduced and a second was converted into an ileoileal intussusception before requiring surgery. The other four intussusceptions were surgically treated. CONCLUSION: Our data suggest that sonographically guided hydrostatic reduction with Hartmann's solution can be used to treat ileocolic intussusception and to diagnose ileoileocolic intussusception.

Catheterization↗
PubMed1995

Sepsis reduces isoflurane MAC in a normotensive animal model of sepsis.

Patients with sepsis often require anaesthesia for surgical procedures. Anaesthesia can be unpredictable and the most haemodynamically stable agents are used. No data are available for the minimum alveolar concentration (MAC) requirements in such patients or in animal models of sepsis. We have characterized the effect of sepsis on the MAC of isoflurane in a normotensive rodent model of sepsis. The minimum inhibitory concentration (MIC) of isoflurane to an identical stimulus was determined for rodents subjected to caecal ligation and perforation (CLP n = 8), or sham laparotomy (n = 7). The calculated MAC of isoflurane was reduced in the septic animals compared with the sham animals (MAC of isoflurane, CLP = 0.8%, sham = 1.4% P < 0.003). No statistical differences were found in the haemodynamic variables measured in either group. Isoflurane leads to haemodynamic stability during anaesthesia in this animal model of sepsis. However, the MAC requirement for isoflurane is reduced by sepsis.

Anesthetics, Inhalation↗
PubMed1995

Pregnancy screening by uterine artery Doppler velocimetry--which criterion performs best?

OBJECTIVE: To test whether repeating Doppler studies of the uteroplacental circulation late in gestation will improve the test's power for predicting pregnancy-induced hypertension and fetal growth restriction (FGR), and whether analysis based on a combination of quantitative and qualitative assessments of the uterine arterial waveforms will yield better results than analysis based on either alone. METHODS: A total of 358 patients considered to be at medium risk for the development of pregnancy-induced hypertension and FGR were recruited. Continuous-wave Doppler studies of the uterine arteries were performed serially at 20, 28, and 36 weeks' gestation. The values of various Doppler indices in the prediction of subsequent pregnancy complications were tested at different gestations and different cutoff levels. The overall significance of performance of the Doppler indices was assessed by the Cohen kappa index, which tests the extent of agreement between the test and the "truth" over that by random chance agreement. RESULTS: A total of 974 examination results on 334 patients were available for analysis. We found that Doppler studies of the uterine arteries at 28 and 36 weeks were less useful than studies performed at 20 weeks. Serial studies at 20 and 28 weeks showed only marginal improvement when compared with a single study at 20 weeks. The best criteria were a mean resistance index (RI) of uterine arteries above the 90th percentile and the presence of diastolic notches in both uterine arteries at 20 weeks. Although the overall kappa index only suggested fair to good agreement beyond chance, the positive predictive value for subsequent complications was good: 57% for severe complications and 93% for any complications. CONCLUSION: Doppler studies of the uterine artery as a test for the subsequent development of pregnancy complications are best performed at 20 weeks with a combination of RI measurements and the assessment of the presence of diastolic notches.

Adult↗