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Brody BL, Gamst AC, Williams RA, Smith AR, Lau PW, Dolnak D, Rapaport MH, Kaplan RM, Brown SI. Depression, visual acuity, comorbidity, and disability associated with age-related macular degeneration. Ophthalmology 2001; 108:1893-900; discussion 1900-1. [PMID: 11581068 DOI: 10.1016/s0161-6420(01)00754-0] [Citation(s) in RCA: 372] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
OBJECTIVE To examine (1) the prevalence of depressive disorders in community-dwelling adults with advanced age-related macular degeneration (AMD) and (2) the relationship in this population between depression, visual acuity, the number of comorbid medical conditions, disability caused by vision loss as measured by the National Eye Institute-Vision Function Questionnaire (NEI-VFQ) and the vision-specific Sickness Impact Profile (SIPV), and disability caused by overall health status as measured by the Sickness Impact Profile-68 (SIP). DESIGN Analysis of cross-sectional baseline data from a randomized clinical trial. PARTICIPANTS Participants were 151 adults aged 60 and older (mean age, 80 years) with advanced macular degeneration whose vision was 20/60 or worse in their better eye. METHODS Subjects were interviewed using measures of depression, disability, and chronic medical conditions. Visual acuity was obtained. Nonparametric correlation analyses and linear regression analyses were performed. MAIN OUTCOME MEASURES Structured Clinical Interview for DSM-IV (SCID-IV), Geriatric Depression Scale (GDS), NEI-VFQ, SIPV, and SIP. RESULTS Of the participants, 32.5% (n = 49) met SCID-IV criteria for depressive disorder, twice the rate observed in previous studies of community-dwelling elderly. Over and above depression (GDS), visual acuity aided in prediction of the level of vision-specific disability (NEI-VFQ and SIPV). CONCLUSIONS Depressive disorder is a significant problem for the elderly afflicted with advanced macular degeneration. Further research on psychopharmacologic and psychotherapeutic interventions for depressed AMD patients is warranted to improve depression and enhance functioning. Over and above depression, visual acuity aided in predicting vision-specific disability. Treatment strategies that teach patients to cope with vision loss should be developed and evaluated.
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Affiliation(s)
- B L Brody
- Department of Ophthalmology, University of California, San Diego, La Jolla, California 92093-0946, USA
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Ko C, Lee TL, Lau PW, Li J, Davis BT, Voyiaziakis E, Allison DB, Chua SC, Huang LS. Two novel quantitative trait loci on mouse chromosomes 6 and 4 independently and synergistically regulate plasma apoB levels. J Lipid Res 2001; 42:844-55. [PMID: 11352992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/16/2023] Open
Abstract
An elevated plasma apolipoprotein B (apoB) level is a strong predictor of atherosclerosis and coronary heart disease. Epidemiologic and family linkage studies have suggested a genetic basis for the wide variations of plasma apoB levels in the general population. Using a human apoB transgenic (HuBTg) mouse model, we have previously shown that hepatic apoB-100 secretion is a major determinant of the high and low plasma human apoB levels in HuBTg mice of the C57BL/6 (B6) and 129/Sv (129) strains, respectively. In the present article, we present the identification of two novel quantitative trait loci (QTL) as major regulators of plasma human apoB levels in the F(2) and N(2) (backcrossed) offspring (n = 572) derived from crosses between the B6 and 129 mouse strains. These loci were designated ApoB regulator genes (Abrg), because the gene products are likely to be involved in the regulation of plasma apoB levels either directly or indirectly. The first locus, designated Abrg1, was mapped to chromosome 6 in 8-week-old male and female mice with a combined logarithm of odds ratio (LOD) score of 14 at the D6Mit55 marker ( approximately 45.9 cM). Abrg1 contributed approximately 35% of the genetic variance. The second locus, designated Abrg2, was mapped to chromosome 4 with an LOD score of 8.6 in 8-week-old male mice but an LOD score of only 2.0 in 8-week-old female mice at the D4Mit27 marker ( approximately 35 cM). Abrg2 contributed approximately 26% of the genetic variance. Epistasis between Abrg1 and Abrg2 was detected and accounted for approximately 12% of the genetic variance. The combination of these two QTL has major effects (>70%) on the regulation of plasma human apoB levels in the tested population. In summary, we have identified two novel loci that have a major role in the regulation of plasma apoB levels and are likely to regulate the secretory pathway of apoB. The human orthologs for the Abrg loci are strong candidates for human disorders characterized by altered plasma apoB levels, such as FCHL and familial hypobetalipoproteinemia.
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Affiliation(s)
- C Ko
- Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
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Chiang AK, Srivastava G, Lau PW, Ho FC. Differences in T-cell-receptor gene rearrangement and transcription in nasal lymphomas of natural killer and T-cell types: implications on cellular origin. Hum Pathol 1996; 27:701-7. [PMID: 8698315 DOI: 10.1016/s0046-8177(96)90401-3] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Although nasal lymphomas showing midfacial destructive lesions had been classified as T-cell lymphomas, their exact cellular origin is still unclear. Although they usually express a restricted number of T-cell-related antigens, namely, CD2, CD43, and CD45RO, other pan-T or subset-T-lineage antigens, such as CD3 (membrane), CD5, CD4, CD8, and CD7, are frequently absent. Conversely, they often express a natural killer (NK) cell-associated antigen, CD56, but lack other mature NK markets. To study their cellular origin further, the authors analyzed T-cell receptor (TCR) gene transcription in three cases of nasal lymphomas and correlated the findings with the phenotype and gene rearrangement data. Two cases of nasal lymphomas with CD2+CD3(Leu4)-CD19-CD56+ phenotype were shown to express truncated 1.0-kb Tbeta and multiple unrearranged Tdelta transcripts with germline TCR beta, gamma, delta, and immunoglobulin heavy-chain joining region (JH) genes, consistent with NK cell lineage. In contrast, one case of nasal lymphoma with CD2+CD3(Leu4)+CD8+CD19-CD56+ phenotype expressed full-length Talpha, Tbeta, and Tgamma transcripts rearranged TCR beta, gamma, and deleted TCR delta genes, indicating T-lineage, These results support the view that nasal lymphomas can separated into NK-cell and T-cell neoplasms, based on differences genotypic characteristics. The possibility of these tumors being derived from a putative common precursor cell merits further investigation.
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Affiliation(s)
- A K Chiang
- Department of Pathology, University of Hong Kong, Pokfulam, Hong Kong
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Lau PW, Cook N, Andrews H, Bracka A, Myint SH. Detection of human papillomavirus types in balanitis xerotica obliterans and other penile conditions. Genitourin Med 1995; 71:228-30. [PMID: 7590713 PMCID: PMC1195518 DOI: 10.1136/sti.71.4.228] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
OBJECTIVES To determine the prevalence of human papillomavirus (HPV) types 6, 11, 16 and 18 in foreskin biopsies from patients with balanitis xerotica obliterans (BXO) and other penile conditions. MATERIALS AND METHODS Foreskin biopsy specimens from 24 patients with penile lesions and 5 control patients were analysed by type-specific polymerase chain reaction (PCR). RESULTS HPV6 or HPV16 were not detected in patients with BXO. HPV6 was detected in 2 controls. CONCLUSIONS Genital papillomaviruses do not have a strong association with BXO.
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Affiliation(s)
- P W Lau
- Department of Microbiology & Immunology, University of Leicester, UK
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Abstract
BACKGROUND One-stage surgery with primary anastomosis is not widely accepted for acute left-sided colonic obstruction. PATIENTS AND METHODS Forty-four patients representing our total admission for acute left-sided colonic obstruction over a 3-year period were evaluated with regard to their suitability for one-stage surgery and primary anastomosis. RESULTS Thirty-five patients (80%) were found to be suitable for this approach and the failures were mainly due to either the advanced nature of the malignant lesions or to their distal location, which precluded an anastomosis. The overall in-hospital mortality was 11%, but only 2 patients (6%) died in the one-stage surgery group, and these deaths were unrelated to anastomotic leakage. This latter complication occurred in 1 patient representing a leak rate of 3%. CONCLUSIONS We recommend, based on our results, the one-stage approach as an alternative to the more conventional primary resection and staged anastomosis.
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Affiliation(s)
- P W Lau
- Department of Surgery, Queen Mary Hospital, University of Hong Kong
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Lorentz TG, Lau PW, Lo CY, Law WL, Wan KY, Lauder IJ. Multivariate analysis of risk factors influencing survival in 110 ethnic Chinese with papillary thyroid cancer. World J Surg 1994; 18:547-50; discussion 551. [PMID: 7725743 DOI: 10.1007/bf00353761] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Data from 110 Chinese patients presenting with papillary thyroid cancer to a single institution up to December 1985 have been analyzed to evaluate the possible risk factors affecting survival. There were 83 women and 27 men with an age range of 15 to 78 years (mean 45 years, median 42 years). The longest follow-up period is 39 years and the median 10 years. Cervical lymph node recurrence more than 6 months after surgery developed in 12 patients, of whom 1 died with a concomitant distant metastasis. "Thyroid bed" tumor recurrence, after apparently complete surgery, presented in 10 patients and resulted in 5 deaths. Distant metastases were identified in 17 patients with 7 deaths. Another 4 patients died from advanced local disease incompletely resectable on presentation. The following seven risk factors for survival were selected for multivariate analysis: age, sex, tumor size, histologic evidence of extrathyroidal spread, lymph node recurrence, neck recurrence, and distant metastases. Age, size, neck recurrence, and distant metastases were all significant on univariate analysis. Using Cox proportional hazards regression in the multivariate analysis of these seven factors, only age (p < 0.0001) was shown to be significant. Age over 40 years on first diagnosis was a highly significant indicator of high risk (p = 0.0003, log-rank).
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Affiliation(s)
- T G Lorentz
- Department of Surgery, University of Hong Kong, Queen Mary Hospital, Pokfulam
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Abstract
Obturator hernia is a rare but important cause of small bowel obstruction that is associated with difficult diagnosis and high mortality. In the past 7 years, 16 patients with small bowel obstruction due to obturator hernia diagnosed at operation were seen at the Department of Surgery, the University of Hong Kong, Queen Mary Hospital. They represented 1% (16 of 1,554) of all hernia repair performed and 1.6% (16 of 1,000) of mechanical intestinal obstruction encountered during the same period. Elderly emaciated women with chronic disease were commonly affected. All patients presented with partial or complete mechanical small bowel obstruction. Right-sided obturator hernia outnumbered left-sided hernia, and bilateral hernia was found in only one patient. The majority of patients required resection of their strangulated small bowel. Most of the hernial orifices were closed with interrupted nonabsorbable sutures. Morbidity and mortality rates were significantly high for this group of debilitated patients with chronic disease who underwent late operation for this elusive diagnosis.
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Affiliation(s)
- C Y Lo
- Department of Surgery, University of Hong Kong Queen Mary Hospital
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Abstract
Phytobezoars are an uncommon but important cause of mechanical small bowel obstruction. Seventeen Chinese patients with small bowel obstruction due to phytobezoars underwent 19 operations at the Department of Surgery, The University of Hong Kong at Queen Mary Hospital, accounting for 2% of mechanical small bowel obstruction treated in the past decade. There were ten men and seven women with an average age of 58 years. All except five patients had previous gastric outlet surgery. The diagnosis depends on a high index of suspicion in patients with partial or complete intestinal obstruction. The bezoars were broken down and milked through the ileocaecal valve in seven cases, whereas enterotomy to retrieve the bezoars or resection of small bowel together with the bezoars was performed on ten and two patient, respectively. There was no postoperative mortality but pneumonia and wound infection occurred in four patients. Because of its potential mortality and associated morbidity, patients with previous gastric surgery should be warned about this preventable complication and be given dietary advice. Phytobezoars should be considered in the differential diagnosis of all patients presenting with mechanical small bowel obstruction.
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Affiliation(s)
- C Y Lo
- Department of Surgery, University of Hong Kong, Queen Mary Hospital
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Abstract
BACKGROUND Incomplete removal of the tumor is the main cause of local recurrence in rectal carcinomas; this often occurs at the lateral aspects devoid of the peritoneum. The authors examined prospectively 80 resected rectal carcinoma specimens in an attempt to discover a reliable method to detect lateral resection margin (LRM) involvement by these tumors and to identify pathologic factors that would be prognostically important. METHODS In each of the 80 resected specimens, the whole tumor was embedded, and whole-mount sections of the entire tumor and the surrounding mesorectum were examined after serial transverse slicing. The distance from the outermost part of the tumor to the LRM (surgical clearance) was measured. RESULTS Six (7.5%) of the 80 specimens showed LRM involvement (defined as surgical clearance < or = 1 mm) in the single slice seen macroscopically to have the deepest tumor invasion, whereas 16 specimens (20%) were found to have LRM involved after examining all slices microscopically. Surgically clearance had a strong inverse relationship with Dukes staging (P < 0.001) and depth of tumor invasion (P = 0.001). The overall local recurrence rate was 28%; it was much higher (53%) in the patients who had LRM involved by tumor. As a whole, local recurrence was related significantly to LRM involvement (P = 0.006). Survival rates were correlated with macroscopic (n = 3) and microscopic (n = 13) features of the resected specimens using Cox multivariate regression analysis. Three of the nine pathologic parameters isolated (i.e., surgical clearance, cellular differentiation, and number of involved pericolic lymph nodes) were identified as favorable independent prognostic factors. CONCLUSIONS Local recurrence is related closely to LRM involvement. Embedding and examining the entire tumor and mesorectum is the only reliable and satisfactory means of assessing LRM. Detailed pathologic study on the resected tumor is important when assessing the prognosis.
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Affiliation(s)
- I O Ng
- Department of Pathology, University of Hong Kong
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Abstract
BACKGROUND Incomplete removal of the tumor is the main cause of local recurrence in rectal carcinomas; this often occurs at the lateral aspects devoid of the peritoneum. The authors examined prospectively 80 resected rectal carcinoma specimens in an attempt to discover a reliable method to detect lateral resection margin (LRM) involvement by these tumors and to identify pathologic factors that would be prognostically important. METHODS In each of the 80 resected specimens, the whole tumor was embedded, and whole-mount sections of the entire tumor and the surrounding mesorectum were examined after serial transverse slicing. The distance from the outermost part of the tumor to the LRM (surgical clearance) was measured. RESULTS Six (7.5%) of the 80 specimens showed LRM involvement (defined as surgical clearance < or = 1 mm) in the single slice seen macroscopically to have the deepest tumor invasion, whereas 16 specimens (20%) were found to have LRM involved after examining all slices microscopically. Surgically clearance had a strong inverse relationship with Dukes staging (P < 0.001) and depth of tumor invasion (P = 0.001). The overall local recurrence rate was 28%; it was much higher (53%) in the patients who had LRM involved by tumor. As a whole, local recurrence was related significantly to LRM involvement (P = 0.006). Survival rates were correlated with macroscopic (n = 3) and microscopic (n = 13) features of the resected specimens using Cox multivariate regression analysis. Three of the nine pathologic parameters isolated (i.e., surgical clearance, cellular differentiation, and number of involved pericolic lymph nodes) were identified as favorable independent prognostic factors. CONCLUSIONS Local recurrence is related closely to LRM involvement. Embedding and examining the entire tumor and mesorectum is the only reliable and satisfactory means of assessing LRM. Detailed pathologic study on the resected tumor is important when assessing the prognosis.
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Affiliation(s)
- I O Ng
- Department of Pathology, University of Hong Kong
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Abstract
When conservative treatment fails in the management of patients with malignant bowel obstruction secondary to advanced, recurrent colorectal cancer, the attitude toward surgery is often less than enthusiastic because of the limited life expectancy. We report a retrospective review of 30 patients with unresectable intra-abdominal disease who underwent laparotomy for the relief of bowel obstruction. Normal bowel function was restored in 19 patients (63 percent). The failures included five patients (17 percent) who died as a result of surgical complications and six patients (20 percent) who despite the surgery had continuing obstruction. Postoperative complications occurred in eight patients (27 percent). The median survival was significantly improved in those who benefited from the operation (192 days vs. 26 days; P = 0.0001). Whether the obstruction occurred at one site or more than one site appeared not to influence the outcome of surgery. Obstruction recurred after a mean symptom-free interval of 120 days in eight of those relieved by the initial operation. Half of these patients responded to conservative treatment, and surgery was again beneficial in three of the remaining four. Our results justify a more positive approach toward this problem, and, when conservatism fails, laparotomy should be undertaken in those who are not terminally ill.
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Affiliation(s)
- P W Lau
- Department of Surgery, University of Hong Kong, Queen Mary Hospital
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Branicki FJ, Coleman SY, Lam TC, Schroeder D, Tuen HH, Cheung WL, Pritchett CJ, Lau PW, Lam SK, Hui WM. Hypotension and endoscopic stigmata of recent haemorrhage in bleeding peptic ulcer: risk models for rebleeding and mortality. J Gastroenterol Hepatol 1992; 7:184-90. [PMID: 1571502 DOI: 10.1111/j.1440-1746.1992.tb00959.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Clinical and endoscopic data were collected prospectively in 1050 patients with bleeding peptic ulcer admitted between September 1985 and July 1989 to the care of one surgical team. Seventy-nine patients underwent therapeutic endoscopy soon after admission and in 129 patients either immediate or early elective surgery was performed. Eight hundred and forty-two patients, in whom therapeutic endoscopy was not performed at any stage, underwent initial conservative management and data from this latter group are now presented. Shock on admission was defined as systolic blood pressure (BP) less than or equal to 100 mmHg on presentation. There were 10 deaths of 147 shocked patients (6.8%) compared with only 25 deaths of 695 patients (3.6%) not in shock (P less than 0.08). Bleeding recurred in 30 patients (20.4%) shocked on presentation but in only 96 (13.8%) with a BP greater than 100 mmHg (P less than 0.05). Twenty-one of 358 patients (5.9%) with endoscopic stigmata of recent haemorrhage (ESRH) died, but only 14 of 484 patients (2.9%) without such stigmata (P less than 0.05) died. In shocked patients rebleeding was evident in 21 of 73 (28.8%) cases with ESRH but in only 9 of 74 (12.2%) patients in whom ESRH were absent (P less than 0.02). In the absence of fresh blood at endoscopy rebleeding occurred in 22 of 124 (17.8%) shocked patients and only 74 of 629 (11.8%) of those not shocked on presentation (P less than 0.07). When ulcer size was documented rebleeding rates for ulcers less than or equal to 1 cm, less than or equal to 2 cm and greater than 2 cm in size were 54 of 485 (11.1%), 30 of 142 (21.2%) and 12 of 44 (27.3%) respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- F J Branicki
- Department of Surgery, Queen Mary Hospital, University of Hong Kong
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Abstract
The ileo-anal pouch procedure is now a well-established method for dealing with ulcerative colitis and familial polyposis in many centres in the West. Experience in the Chinese population is not well documented, mainly due to the rarity of inflammatory bowel disease. This report documents the experience of a university teaching hospital in Hong Kong. Despite being a small series, the low complication rates and good functional results show that the pelvic pouch procedure has now evolved to a stage where it can be performed safely even in centres with infrequent experience.
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Affiliation(s)
- P W Lau
- Department of Surgery, Queen Mary Hospital, University of Hong Kong
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Branicki FJ, Coleman SY, Pritchett CJ, Cheung WL, Tuen H, Fok PJ, Fan ST, Lai EC, Lau PW, Mok FP. Emergency surgical treatment for nonvariceal bleeding of the upper part of the gastrointestinal tract. Surg Gynecol Obstet 1991; 172:113-20. [PMID: 1989114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Endoscopic and biochemical data were collected prospectively from 1,530 patients admitted with nonvariceal bleeding of the upper part of the gastrointestinal tract between September 1985 and June 1989. Therapeutic endoscopy was done for 93 patients who underwent emergency surgical treatment for bleeding, subsequently required in 29 patients with seven postoperative fatalities. In contrast, 31 (15.7 per cent) of 198 patients (mortality rate of 9.6 per cent at 30 days) died in the hospital who had undergone emergency operation in whom therapeutic endoscopy had not been performed; data for this latter group is now presented. At admission, a greater likelihood of emergency operation was associated with a systolic blood pressure of 100 millimeters of mercury and endoscopic stigmatas of recent hemorrhage (ESRH) (p less than 0.001). Rebleeding rates for the presence of fresh blood, active spurting and oozing hemorrhage or visible vessel in an ulcer base were 26.5, 28.9 and 35.9 per cent, respectively. Endoscopic stigmatas were thus associated with an increased risk of bleeding (p less than 0.0001) and rebleeding led to a sixfold increase in the mortality rate. Congestive cardiac failure, chronic obstructive airway disease, chronic renal failure and a history of previous malignant disease were each associated with postoperative mortality rates of more than 50 per cent. An increased risk of mortality after emergency operation was related to age (p less than 0.0001), preoperative (p less than 0.002) and total (p less than 0.0001) blood transfusion requirement. Immediate operation after resuscitation and endoscopy was required in 87 patients; 11 deaths (hospital mortality rate of 12.7 per cent and 9.2 per cent at 30 days) occurred in this group compared with 20 fatalities (18.0 per cent) documented in 111 patients (9.9 per cent at 30 days) who underwent surgical treatment for rebleeding. We conclude that age, concomitant medical illness and preoperative and total transfusion requirements are each related to outcome after emergency operations. Such urgent intervention is best avoided if at all possible in patients with severe concomitant medical illness.
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Affiliation(s)
- F J Branicki
- Department of Surgery, University of Hong Kong, Queen Mary Hospital
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Branicki FJ, Coleman SY, Fok PJ, Pritchett CJ, Fan ST, Lai EC, Mok FP, Cheung WL, Lau PW, Tuen HH. Bleeding peptic ulcer: a prospective evaluation of risk factors for rebleeding and mortality. World J Surg 1990; 14:262-9; discussion 269-70. [PMID: 2327100 DOI: 10.1007/bf01664889] [Citation(s) in RCA: 98] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Clinical, endoscopic, and laboratory data were collected prospectively in 701 patients with bleeding peptic ulcer. The overall rebleeding rate was 16.1% and increased the risk of a fatal outcome by 17 fold (1.2% versus 20.6%, p less than 0.001). Rebleeding was documented in more than 75% of the group who did not survive following initial conservative management. Rebleeding was more likely (24.1% versus 14.2%, p less than 0.02) when shock was present on admission and the risk of a rebleed was doubled in patients over 60 years of age (22.1% versus 10.9%, p less than 0.001). Ulcers greater than 1 cm in size carried twice the risk of rebleeding (23.9% versus 12.4%, p less than 0.002). Concomitant medical illness had a significant adverse effect on outcome (p less than 0.05). Shock on admission was associated with a doubling of mortality figures (9.5% versus 3.7%, p less than 0.01). The identification of endoscopic stigmata of recent hemorrhage (ESRH) tripled the risk of mortality (7.5% versus 2.4%, p less than 0.002), ESRH were more frequently encountered when ulcer size was larger than 1 cm (61.4% versus 39.8%, p less than 0.001). Respective mortality rates for ulcers less than or equal to 1 cm and greater than 1 cm in size were 1.6% and 12.5% (p less than 0.001), corresponding mortality figures for patients over 60 years of age being 4.4% and 16.4% (p less than 0.002). The risk of a rebleed tripled (6.7% versus 2.6%, p less than 0.02) when ESRH were evident. There was a 6-fold increase in mortality following emergency surgery when compared with conservative management of patients in whom no surgical intervention was necessary (2.6% versus 14.9%, p less than 0.001). In summary, age over 60 years, previous medical illness, shock on admission, large ulcer size, and ESRH were each associated with an increased risk of rebleeding and mortality.
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Affiliation(s)
- F J Branicki
- Department of Surgery, University of Hong Kong, Queen Mary Hospital
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Lau PW, Asakura T. Comparative study of oxygen and carbon monoxide binding by hemoglobin. J Biol Chem 1980; 255:1617-22. [PMID: 6243644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
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Lau PW, Asakura T. Use of heme spin-labeling to probe heme environments of alpha and beta chains of hemoglobin. J Biol Chem 1979; 254:2595-9. [PMID: 218946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
A spin label attached to a propionic acid group of the heme has been used to probe the heme environment of the alpha and beta chains of hemoglobin in both the subunit and tetrameric forms. The electron paramagnetic resonance (EPR) studies of hemoglobin hybrids in which the spin label is attached to either the alpha- or beta-heme (alpha2SLbeta 2 or alpha2beta2SL) and spin-labeled isolated chains (alphaSL and betaSL) show that: 1) alpha- and beta-hemes have different environments in the tetrameric forms of oxy-, deoxy-, and methemoglobins as well as in isolated single chains; 2) when isolated subunits associate to form hemoglobin tetramers, the environment of the alpha-heme changes more drastically than that of the beta-heme; 3) upon deoxygenation of hemoglobin, the structure in the vicinity of the alpha-heme changes more drastically than that of the beta-heme; and 4) upon the addition of organic phosphates to methemoglobin, the change in the spin state of the heme irons mainly arises from beta-heme. The results demonstrate conclusively that the alpha and the beta subunits of hemoglobin are structurally nonequivalent as are their structural changes as the result of ligation. The relationship of EPR spectrum and structure of hemoglobin is discussed.
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Lau PW, Hung C, Minakata K, Schwartz E, Asakura T. Spin-label studies of membrane-associated denatured hemoglobin in normal and sickle cells. Biochim Biophys Acta 1979; 552:499-508. [PMID: 221019 DOI: 10.1016/0005-2736(79)90194-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
A maleimide spin label (N-(1-oxyl-2,2,5,5-tetramethylpyrrolidinyl)-maleimide) was reacted with oxyhemoglobin-free cell stromata of normal and sickle cells. The EPR spectrum of spin-labeled red cell membranes showed that the spin labels are attached to at least two different binding sites. There was a major signal, A, which characterized a strongly immobilized environment and a minor signal, B, which characterized a weakly immobilized environment. Quantitative EPR measurements using equal amounts of Hb AA and Hb SS red blood cells demonstrated that Hb SS red cell membranes had an approximately four times higher EPR signal intensity than Hb AA red cell membranes ((7.98 +/- 1.14 . 10(5) and (2.2 +/- 1.2) . 10(5) spin labels/cell, respectively). Moreover, the ratio of signal intensities A and B are different in these cells. Comparative spectrophotometric studies of membrane-associated denatured hemoglobins of Hb AA and Hb SS red cell membranes suggested that the EPR signal A is derived from spin labels attached to membrane-associated denatured hemoglobin, while signal B is mainly from spin labels attached to membranes. The combination of EPR spectrum of Hb AA membranes pretreated with N-ethylmaleimide and that of spin-labeled precipitated hemoglobin further strengthened this conclusion.
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Abstract
A nitroxide spin-label probe was attached directly to a propionic acid group of heme in either the alpha or the beta chain of hemoglobin. The electron paramagnetic resonance (EPR) spectrum of the spin label is altered by the spin-state change of the heme iron to which the spin label is attached. These hybrid hemoglobins showed normal optical and functional properties, indicating that the attachment of the spin label did not perturb the function of hemoglobin. Upon deoxygenation of alpha-heme-spin-labeled hemoglobin, EPR signals changed proportionally with oxygen saturation (determined by measuring absorption spectra). This result indicates that there is no binding preference between the alpha and beta chains of hemoglobin. However, the cross plot for the fraction of the EPR changes vs. the fraction of oxygen saturation deviated significantly from the diagonal straight line in response to the addition of 2,3-diphosphoglycerate and inositol hexaphosphate. The deviation indicated that the EPR change precedes the optical change at low oxygen tension. This result implies that, in the presence of organic phosphate, oxygen binds preferentially to the alpha subunit of deoxyhemoglobin. This conclusion was supported by the result obtained with beta-heme-spin-labeled hemoglobin: the direction of the deviation for beta-heme-spin-labeled hemoglobin in the presence of diphosphoglycerate and inositol hexaphosphate was opposite to that obtained for alpha-heme-spin-labeled hemoglobin. However, the curve deviated even in the absence of organic phosphate. This deviation for beta-heme-spin-labeled hemoglobin can be explained by the intersubunit interaction of hemoglobin. From these results, it was concluded that, in the absence of organic phosphate, oxygen combines with the alpha and beta chains with equal probability whereas, in the presence of organic phosphate, oxygen binds preferentially to the alpha chains of hemoglobin.
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Lau PW, Lin WC. Electron spin resonance of transition metal ions in calcium tartrate tetrahydrate host lattice I. Mn2+, Cu2+, and Ni2+ as dopants. J Chem Phys 1973. [DOI: 10.1063/1.1680588] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Lau PW, Lin WC. Electron Spin Resonance of Two Radicals Formed in X‐Irradiated Cyanoacetylurea, Another Sigma‐Electron Radical of the RCOṄH Type. J Chem Phys 1969. [DOI: 10.1063/1.1671913] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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