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Biomedical subjects

K M Chen

Publications and source records attributed to K M Chen.

At least 55 records · Page 3Linked to original sources

Surgical treatment of peptic ulcer disease: changing patterns in the past 40 years.

During the past 40 years (1951-1990), 7,663 patients with peptic ulcer disease underwent surgical treatment at the National Taiwan University Hospital. A great change in patient characteristics and operative procedures was noted between the last 10 years and the previous three decades. There were 7,105 patients (92.7%) between 1951 and 1980, an average of 237 patients per year. However, only 558 patients received surgery in the last 10 years, an average of 56 patients per year. The proportion of female patients increased from 9.5% in the earlier period to 20.4% in the last 10 years; the average age of patients also increased. In the earlier period, the indications for surgery were hemorrhage (38.4%), perforation (36.1%), intractable pain (16.4%) and stenosis (9.1%). Perforation (89.2%) was the most common indication for surgical treatment in the last 10 years. Hemorrhage (4.9%), pain (4.1%) and stenosis (1.8%) were less common. There was no significant difference in surgical morbidity between the two periods. Primary subtotal gastrectomy (SG) accounted for 75.4% of operations in the earlier period, but vagotomy became the main treatment in the last 10 years, including highly selective vagotomy (HSV) (31.9%), and truncal vagotomy with drainage procedure (TV + D) (31.0%). The surgical mortality in the earlier period was 1.3% for SG, 1.8% for TV + D and 16.1% for simple closure. There was no significant change in ulcer location between the two periods. The overall mortality rate was higher in the last 10 years (5.2%) than in the earlier 30 years (2.7%) (p < 0.001). In follow-up studies, the satisfactory rate after operation was similar among patients receiving SG (89.8%), HSV (90.3%) and TV + D (91.1%) between 1977 and 1990.

Adolescent↗

Endoscopically-assisted duodenal feeding tube placement using a nasogastric tube: preliminary two-year experience.

Our initial 2-year experience using a new technique of nasoduodenal feeding tube placement with a soft nasogastric tube is presented. This technique was used for patients with major burns to initiate early, safe enteral feeding. With the use of double loops in the tube and endoscopic assistance, the placement of the nasogastric tube beyond the second portion of the duodenum was accomplished in approximately 20 minutes. A method of transpyloric duodenal intubation using a soft, unstented nasogastric tube that allowed rapid bedside nasoduodenal intubation, with the patient in the supine position, was used. The tube placement technique minimizes the suffering of critically ill patients and the labor of clinicians performing the tube placement.

Burns↗

Comparison between resectable gastric adenocarcinomas seropositive and seronegative for Helicobacter pylori.

The preoperative seropositivity of Helicobacter pylori was determined in 128 patients who had undergone gastrectomy for primary gastric adenocarcinoma during the past 5 years. The overall seroprevalence of H. pylori was 64 per cent. Gastric cancers positive for H. pylori were associated with tumours located in the lower third of the stomach which were of localized type (Borrmann I and II) (P < 0.05), but not with age, sex, blood type, tumour size, invasion depth, lymph node metastases, histological type, DNA ploidy or type of surgery. The cumulative 5-year survival curves after surgical resection were significantly better in patients who were positive for H. pylori. Multivariate analysis revealed that seropositivity for H. pylori was not an independent prognostic factor. Pathological tumour node metastasis staging was the only prognostic indicator. Better prognosis for those with H. pylori-seropositive gastric cancer may be attributed to the more advanced stage of H. pylori-seronegative gastric cancers. The potential role of H. pylori in gastric cancer carcinogenesis and its biological significance warrant further investigation.

Adenocarcinoma↗

Effects of lipids on intestinal adaptation following 60% resection in rats.

The effects of long-chain triglycerides (LCT) and of medium-chain triglycerides (MCT) on intestinal adaptation in rats were compared following a 60% resection of intestine. Sixty Long-Evans rats were divided into four groups: control (sham-operated) rats fed an MCT-enriched diet, control rats fed an LCT-enriched diet, experimental rats fed an MCT-enriched diet, and experimental rats fed an LCT-enriched diet. In the MCT-enriched diet, 90% of the fat was MCT; in the LCT diet, 90% was LCT. In each diet, 31-32% of daily caloric intake came from fat. All diets were isocaloric and isonitrogenous. Following the 60% intestinal resection from the mid-portion of the small intestine, there were significant increases in mucosal height, villous height, villous width, and crypt depth (P < 0.05). Gut weight, mucosal weight, protein and DNA content, and DNA synthetic rate also increased. In the ileum, rats receiving the LCT diet showed greater increases in gut weight, mucosal weight, crypt depth, protein and DNA content, and DNA synthetic rate than the MCT rats did (P < 0.05). In the jejunum, however, the differences were not statistically significant. In both the jejunum and the ileum, the response of the intestine was greater closer to the anastomotic site (P < 0.05). Results of these studies demonstrated that LCT had a better effect than MCT on intestinal response both structurally and functionally.

Adaptation, Physiological↗

Breast cancer angiogenesis: a quantitative morphologic and Doppler imaging study.

BACKGROUND: Tumor growth and metastases require the development of new vessels (angiogenesis). Angiogenesis, assessed by microvessel count using immunocytochemical stain of endothelial cells, has been shown to predict metastases and correlate with early death. Recently developed color Doppler mapping can detect the "tumor flow signals" in breast cancer and help to distinguish it from benign lesions. The question is, does this tumor vascularization assessed by color Doppler mapping correlate with the angiogenesis assessed by immunocytochemistry? METHODS: Eighty-four patients admitted for breast surgery were studied. The final diagnosis was made by pathology for 52 malignancies and 32 benign lesions. The color Doppler mapping of the breast lesion was made preoperatively. The following parameters were assessed: (a) vessel location (peripheral or central); (b) density of color Doppler signals; and (c) maximum systolic velocity. Tumor angiogenesis was assessed by microvessel count under light microscopy using the platelet/endothelial cell adhesion molecule antibodies (CD31) method. The correlation between maximum velocity and microvessel count of breast cancer was examined. The clinical significance of maximum flow velocity of breast cancer with various clinicopathologic factors was assessed. RESULTS: Color signals were detected in 48 cases of 52 malignancies (92%). All tumors demonstrated signals at the periphery of the lesion but in only 13 (27%) were the signals detected within the tumor. Color signals were scored as + + or + + + in 44 (92%) patients. Pulsed wave blood flow was shown in all these 48 tumors, with maximum velocities varying from 4 to 36 cm/s. Among the 32 benign lesions, color signals were detected in 10 (31%) and all were peripheral and scored subjectively as +. Evaluation of these color Doppler mapping parameters shows no significant correlation with microvessel counts using CD31 monoclonal antibodies. However, there was a positive association (p < 0.05) between nodal metastases and higher tumor flow velocity in T1 (< 2 cm) breast tumors but not in larger tumors. CONCLUSION: Although the color Doppler mapping has been shown to be useful in distinguishing benign from malignant breast lesions, the intensity of signal and velocity of flow had no correlation with the extent of angiogenesis of breast cancer. The presence of high-flow tumor signal in early breast carcinoma is significantly associated with the presence of axillary lymph node metastases.

Adult↗

Activity changes of ATP synthase and adenylate kinase in rat-liver mitochondria during the early phase after burn injury.

Using succinate as a substrate, the activities of ATP synthase and adenylate kinase in liver mitochondria of male Sprague-Dawley rats 30 min after 20 per cent full skin thickness burns were increased in comparison with the sham burn rats, suggesting that these two enzymes might contribute to the increased rates of ATP formation and oxidative phosphorylation coupling during the early phase after burn injury.

Adenylate Kinase↗

Clinicopathologic characteristics of Helicobacter pyloric seropositive gastric adenocarcinomas.

To compare and characterize retrospectively the clinicopathologic features of gastric cancers with and without previous Helicobacter pylori infection, we determined the preoperative seropositivity of H. pylori in 151 patients who had undergone gastric resection for primary gastric adenocarcinoma between 1988 and 1993. The overall seroprevalence of H. pylori was 60.9%. H. pylori-positive gastric cancers were frequently associated (p<0.05) with macroscopic localized types (Borrmann I and II) in which negative cancer associated with infiltrative types (Borrmann III and IV) and cancer invasion of the duodenum. Multivariate analysis showed that H. pylori seropositivity was not an independent prognostic factor. Pathologic tumor-node-metastases (TNM) stage remained the only prognostic indicator. Our study suggests that H. pylori has a significant impact on the clinically relevant tumor biology of gastric cancer. Investigation along this line is warranted.

Adenocarcinoma↗

Surgical treatment of gastric adenocarcinoma: the role of lymph node dissection.

In this retrospective study, 652 patients who had curative resections for gastric cancer from 1977 to 1991 were reviewed to evaluate improvements in gastric cancer surgery and the influence of the extent of lymphadenectomy on survival. The patients were grouped into three time periods: 1977 to 1981, 1982 to 1986 and 1987 to 1991. The percentage of patients with early gastric cancer increased from 17.7% during 1977 to 1981, to 24.3% during 1987 to 1991. The average number of dissected lymph nodes was 7.5 +/- 8.1 during 1977 to 1981 and 16.4 +/- 10.3 during 1987 to 1991, when more radical lymphadenectomy was adopted. Total gastrectomies increased from 10.9% to 25.9% in the same time periods while combined visceral resections increased from 26.7% to 38.1%. Operative mortality decreased from 5.0% to 1.7%. The overall 5-year survival rate increased from 34.8% to 59.4%. In subgroup analysis, significant improvement of the 5-year survival rate was noted in the following groups: patients with stage I, II and III tumors but not stage IV; both proximal and distally located tumors; tumors with or without lymph node metastases; T1 and T2 but not in T3 and T4 (cancer invasion beyond the serosa). The decreased surgical mortality in recent years suggests that curative resection with extensive lymph node dissection can now be safely performed. Radical gastrectomy with extended lymphadenectomy may be adopted in gastric cancer resection for better control of regional disease.

Adenocarcinoma↗

Fulminant amebiasis: a clinical evaluation.

Two patients with fulminant amebic colitis with colon perforation and concomitant liver abscess were collected over the last 5 years. One patient underwent emergency laparotomy to treat amebic cecal perforation. Diverted ileostomy saved his life. The ileostomy was successfully reversed 6 months later. The other patient underwent 4 laparotomies with more invasive procedures in less than 1 month due to sequential complications of amebiasis. Colon resection with enterostomy miraculously allowed him to survive. In comparison with the latter, who underwent more aggressive surgery and experienced more catastrophic complications, the former with conservative surgery had a smoother clinical result. Thus, conservative operation for colon perforation due to amebiasis is recommended. Besides, thanks to the alertness of doctors, the favorable age of the patients, the advent of new antiamebic and antimicrobial agents, excellent hyperalimentation, the great improvement in medical facilities and postoperative care, the two critical patients eventually survived after several operations, and had a better outcome as compared with the high mortality rate of 87.5% in our hospital 2 decades earlier.

Adult↗

Adenocarcinoma of the gastric cardia: prognostic significance of pathologic and treatment factors.

The records of 146 patients who had surgery for adenocarcinoma of the gastric cardia between 1977 and 1992 at National Taiwan University Hospital were retrospectively analyzed. The prognostic significance of pathologic and surgical treatment factors was examined by log rank test and stepwise regression procedures. The overall 2-year and 5-year survival rates were 40.2% and 23.7%, respectively. The pathologic factors analyzed included: age, sex, tumor diameter, esophageal invasion, pathologic grading, vascular invasion, perineural invasion, depth of invasion, node-status, distant metastasis and number of positive lymph nodes. The surgical treatment factors analyzed included:surgical procedure, region of lymphadenectomy, resection margin and resection status. Resection status was classified into three categories: absolute curative, relative curative and palliative. Univariate analyses showed that esophageal invasion, vascular invasion, depth of invasion, node status, node number, resection margin and resection status were significant prognostic factors. The selected stepwise regression model identified three significant independent factors: node status, resection status and esophageal invasion. Aggressive surgical management, including combined resection and extended lymphadenectomy, may be helpful for patients with adenocarcinoma of the gastric cardia.

Adenocarcinoma↗

[Disappearance of ALS from Guam: implications for exogenous causes].

The author reports the disappearance of amyotrophic lateral sclerosis (ALS) from Guam over past 30 years, which coincided with rapid changes in the ecology, socioeconomy, and westernization of the life style. This slow but steady decline is believed to be the consequences of radical changes from food collection to wage-based life style and dietary improvement in recent years and elimination of exogenous factors. Those risk factor(s) are believed to be the environmental trace metals which must have triggered the accelerated oxidative stresses in the motor neurons of genetically susceptible population. Changing Epidermiology: 1. The annual incidence of 70/100,000 in 1960s down to 7/100,000 in 1990s, and remained unchanged for past 15 years. 2. Upward shift of age at onset by 10 years and at death by 8 years and even out of sex ratio. 3. Birth cohort analysis showed less risks for those born after 1920. No ALS cases born after 1945. 4. No increase in the incidence of ALS among non-Chamorros transients of Guam and Marianas during W.W.II. 5. Long-term resident non-Charmorro and half-Chamorros on Guam are also affected. 6. Charmorro migrants to U.S. Mainland are affected after long absence from Guam. 7. Incubation period for both ways is estimated to be 18 approximately 20 years. 8. Other forms of dementias like Alzheimer disease (AD) and vascular dementias are on the rise and the leading cause of death is cerebro- and cardiovascular diseases. 9. ALS is also declining in past 10 approximately 15 years in Kii peninsula, and West New Guinea. Changing Ecology of Guam: 1. One third of Island land was used for construction of huge military bases after W.W.II. 2. Urbanization of villages including concrete houses, deep well water supply, sewage, and electrification. 3. Tourism boom: high-rise hotels, development of 7 golf courses and other recreational facilities resulted in loss of flora and erosions of soil. Socioeconomic Changes: 1. Shift in population demography; Efflux of Chamorros and influx of aliens; Chamorros less than 50% by 1990. 2. Tourists passed 1 million in 1994. 3. Automobiles 1 car/1.5 person. 4. Westernization: After W.W.II, almost free access to Military Commissary for imported food and appliances. 5. Life style: from food collection to wage-based society. Genetic Studies: 1. Familial aggregations, but no clear-cut Mendelian inheritance. 2. Segregation analysis: no absolute genetic or environmental cause but additive gene component may play a role in genetic susceptibility and basis for geographical clustering. 3. Absence of Apo-E or Mu/Zn SOD genes. 4. Recent discovery of mtDNA Complex I deficiency in Parkinsonism-dementia cases suggests mitochondrial DNA abnormality. Comparative Environmental Studies: 1. Environmental studies in three hyperendemic areas in the Western Pacific--Kii, Marianas, and west New Guinea, where strikingly high incidences of ALS is known to occur, found the identical geochemical environment--low Ca, Mg, and Zn and high A1, Mn, Fe, Si, in the garden soil and drinking water. 2. Exogenous etiologic factors that are absent from primitive culture of Auyu and Jackai tribes in West New Guinea were eliminated. 3. Cycad neurotoxicity has been excluded. 4. Suspected exogenous agents that are common in these 3 hyperendemic areas are (a) locally grown vegetables, starchy roots, and reef fish; (b) surface water containing soluble organic minerals from red laterites; (c) rain water that is chemically pure and lack of essential minerals. Pathogenic Speculation: Chronic dietary deficiency since birth in Ca, Mg and Zn induced excessive absorption of divalent cations which accelerates oxidant-mediated neuronal degenerations in a genetically susceptible population. The process is probably carried through interactions between cytoskeletal abnormality of the neuron, aging process, abnormal proteins, and mitochondrial dysfunction.

Amyotrophic Lateral Sclerosis↗

Selective depression of T-lymphocyte subsets in gastric cancer patients: an implication of immunotherapy.

The lymphocytes and their subsets were determined in the peripheral blood of 62 gastric cancer patients and 68 controls using fluorescent conjugated monoclonal antibodies and flow cytometry (FACScan method). A significant increase in the total number of white blood cells from gastric cancer patients was noted in comparison to controls, but the percentage of lymphocytes was the same. The percentage of suppressor (cytotoxic) T cells (CD8) showed no difference in all stages of gastric cancer patients evaluated, but the percentage of helper (inducer) T cells (CD4) and the CD4/CD8 ratio decreased significantly in the advanced stages III and IV. Depression of the CD4/CD8 ratio was well correlated with tumor invasion, lymph node metastasis, and tumor size but not with sex, age, tumor location, gross type, or histologic differentiation. It appeared that the immune defect of gastric cancer patients was associated with the afferent arm (CD4) and worsened as the disease advanced. These results suggest that immunotherapy to stimulate the deficient immune system may play an important part in the multimodality treatment of patients with advanced gastric cancer.

CD4-CD8 Ratio↗

The neostriatum and nucleus accumbens in parkinsonism-dementia complex of Guam: a pathological comparison with Alzheimer's disease and progressive supranuclear palsy.

The neostriatum, nucleus accumbens and basal nucleus of Meynert (bnM) in the parkinsonism-dementia complex of Guam (Guam PDC) were examined immunohistologically, ultrastructurally, quantitatively and topographically, and the results were compared with those in Alzheimer's disease (AD) and progressive supranuclear palsy (PSP). Compared to neurologically normal controls, the number of large neurons in Guam PDC was reduced by approximately 70% in the caudate nucleus and putamen and by more than 90% in the nucleus accumbens. The decreased number of large neurons in the neostriatum was significantly correlated to that in the bnM. The remaining large neurons and many of the medium-sized neurons in the neostriatum and nucleus accumbens were immunopositive for tau protein and contained varying amounts of 21- to 25-nm-wide paired helical filaments (PHFs) admixed with straight tubules. Curly fibers and circularly arranged reactive astrocytes were seen in the nucleus accumbens of many PDC patients. Collectively, these findings, which are similar in part to those of AD and differ from those of PSP, suggest that the large neurons in the neostriatum and nucleus accumbens in Guam PDC degenerate through PHF formation, and that extremely severe loss of large neurons in the nucleus accumbens may be linked to marked degeneration of the limbic and ventral tegmental areas and nucleus dorsal raphe.

Adult↗

Amyotrophic lateral sclerosis of Guam: the nature of the neuropathological findings.

To elucidate the fundamental differences and similarities of the neuropathological features and etiopathogenesis of the amyotrophic lateral sclerosis (ALS) and parkinsonism-dementia complex (PDC) of Guam, we conducted a topographic, quantitative and histological investigation of tau-containing neurons, neurofibrillary tangles (NFTs), Bunina bodies and ubiquitinated inclusion bodies in 27 non-ALS non-PDC Guamanian subjects, as well as 10 Guam ALS patients, 28 PDC patients, and 5 patients with combined ALS and PDC (ALS-PDC). The topographic distribution of NFTs was basically the same in each disease and also in the non-ALS non-PDC group. There were relatively few, if any, NFTs in non-ALS non-PDC subjects and ALS patients, but there were many, especially in the frontal and temporal cortex, in Guam PDC and ALS-PDC patients. The histological and ultrastructural features of Bunina bodies in Guam ALS and ALS-PDC patients were similar to those reported in classic ALS. The ratio of occurrence of the inclusion in Guam ALS and ALS-PDC patients was similar to that reported so far in classic ALS. Ubiquitinated skein-like inclusion bodies were observed in the spinal anterior horn cells in Guam ALS and ALS-PDC patients. These findings indicate that classic ALS does exist on Guam, that NFTs in Guam ALS patients are merely a background feature widely dispersed in the population, that the mechanism of neuronal degeneration of Guam ALS is basically different from that of PDC, and that Guam ALS occurs initially are classic ALS.

Adult↗

Laparoscopic assisted gastrostomy tube placement.

Gastrostomy commonly is performed for patients who have esophageal stenosis or difficulty in swallowing. The fact that most patients who require a gastrostomy are malnourished or debilitated urges surgeons to seek a safe and simple procedure. Percutaneous endoscopic gastrostomy (PEG) was introduced into clinical use and recommended as the procedure of choice in the 1980s. However, for patients with obstruction of the oroesophageal canal, PEG was not possible, and only traditional open gastrostomy could be considered. We describe a technique for placement of a gastrostomy tube under laparoscopic guidance. The technique is simple and easily mastered, requires equipment routinely used in laparoscopic surgery, and can be used by surgeons without gastroendoscopic experience. When performed properly, the method is simple, economical, and reliable.

Enteral Nutrition↗