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T Koperna

Publications and source records attributed to T Koperna.

At least 19 recordsLinked to original sources
PubMed2004

The surgical management of elderly cancer patients; recommendations of the SIOG surgical task force.

Although cancer in the elderly is extremely common, few health professionals in oncology are familiar with caring for series of oncogeriatric patients. Surgery is at present the first choice, but is frequently delivered suboptimally: under-treatment is justified by concerns about unsustainable toxicity, whilst over-treatment is explained by the lack of knowledge in optimising preoperative risk assessment. This article summarises the point of view of the Surgical Task Force @ SIOG (International Society for Geriatric Oncology), pointing out differences from, and similarities to, the younger cohorts of cancer patients, and highlighting the latest updates and trends specifically related to senior cancer patients.

Advisory Committees↗
PubMed2001

Risk stratification in emergency surgical patients: is the APACHE II score a reliable marker of physiological impairment?

HYPOTHESES: The APACHE II (Acute Physiology and Chronic Health Evaluation II) score used as an intensive care unit (ICU) admission score in emergency surgical patients is not independent of the effects of treatment and might lead to considerable bias in the comparability of defined groups of patients and in the evaluation of treatment policies. Postoperative monitoring with the APACHE II score is clinically irrelevant. DESIGN: Inception cohort study. SETTING: Secondary referral center. PATIENTS: Eighty-five consecutive emergency surgical patients admitted to the surgical ICU in 1999. The APACHE II score was calculated before surgery; after admission to the ICU; and on postoperative days 3, 7, and 10. MAIN OUTCOME MEASURES: APACHE II scores and predicted and observed mortality rates. RESULTS: The mean +/- SD APACHE II score of 24.2 +/- 8.3 at admission to the ICU was approximately 36% greater than the initial APACHE II score of 17.8 +/- 7.7, a difference that was highly statistically significant (P<.001). The overall mortality of 32% favorably corresponds with the predicted mortality of 34% according to the initial APACHE II score. However, the predicted mortality of 50% according to the APACHE II score at admission to the ICU was significantly different from the observed mortality rate (P =.02). In 40 long-term patients (>/=10 days in the ICU), the difference between the APACHE II scores of survivors and patients who died was statistically significant on day 10 (P =.04). CONCLUSIONS: For risk stratification in emergency surgical patients, it is essential to measure the APACHE II score before surgical treatment. Longitudinal APACHE II scoring reveals continuous improvement of the score in surviving patients but has no therapeutic relevance in the individual patient.

APACHE↗
PubMed2001

[Anastomosis protection and preservation of continence in the surgical treatment of rectal carcinoma].

AIMS: To find clues to a risk-adjusted therapy with regard to the use of protective colostomies and the value of Hartmann-resection. METHODS: In 108 patients with rectal cancer the results of surgical treatment were examined during a period from 1996 to 1998. RESULTS: One surgeon always performed a defunctioning colostomy in low anterior resection if the patients were male with lower and advanced tumors after preoperative radiation, while others carried out anastomotic protection in none of these patients. Anastomotic dehiscence never occurred in these patients, but in male patients with more proximal tumors and without preoperative radiation. Overall, preoperative radiation did not result in a higher rate of complications and local recurrence never occurred. Nineteen patients with high comorbidity underwent Hartmann-resection as a therapy with assumed lower risk for postoperative complications when compared with abdomino-perineal resection. The postoperative mortality rate of 16% was well above the mean postoperative mortality of 4.6%. Local recurrence occurred in 31% in comparison with 16% after abdomino-perineal resection, but all of these patients were operated on for obstructing node-positive T4-tumors. CONCLUSIONS: Technical difficulties in performing a low rectal anastomosis should be more important for the indication of anastomotic protection than generalizing guidelines. Preoperative short-term radiation is safe and has a beneficial effect on local recurrence. The Hartmann-resection is advisable only in patients with colonic obstruction and locally advanced tumors and in patients with a markedly higher comorbidity, in whom the risk of an anastomosis is not justified.

Adult↗
PubMed2000

Relaparotomy in peritonitis: prognosis and treatment of patients with persisting intraabdominal infection.

Some patients are prone to persisting intraabdominal infection regardless of initial eradication of the source of infection. Our aim was to characterize patients who had to undergo relaparotomy for persisting abdominal sepsis using simple clinical parameters and to define those patients who are susceptible to benefit of aggressive surgical treatment by early and repeated reoperations to control multiple organ dysfunction syndrome (MODS) caused by ongoing intraabdominal infection. Persisting abdominal sepsis was the cause of death in all of our patients who had to undergo relaparotomy. Controlling persisting abdominal sepsis should achieve a reduction in the tremendously high mortality rate. Performing a case-control study, we retrospectively reviewed 523 consecutive patients with secondary peritonitis treated from 1986 to 1996 and focused our attention on 105 patients, in whom standard surgical treatment of secondary peritonitis failed and who had to undergo relaparotomy for persisting abdominal sepsis (study group). Overall, there was no significant difference in the postoperative mortality rate between "planned relaparotomy" and "relaparotomy on demand" (54.5% versus 50. 6%). Equally clear risk estimations were given preoperatively by both the Acute Physiology and Chronic Health Evaluation (APACHE) II and the Goris scores. There was a significant difference between patients of the control group and patients of the study group with regard to preoperative APACHE II score, Goris score, age >70 years, albumin <30 g/L, extent of peritonitis, and outcome (p = 0.0001). Reexploration performed more than 48 hr after the initial operation resulted in a significantly higher mortality rate (76.5% versus 28%; p = 0.0001). However, the time of reoperation had no significant impact on survival in patients with an APACHE II score of > or = 26, because physiologic derangement is such that only a few patients could benefit from reoperation. The lowest mortality rate (9%) was achieved in patients who underwent reoperation on demand within 48 hr. We conclude that patients >70 years of age with secondary peritonitis extending over the entire abdomen and a greater degree of physiologic compromise (serum albumin levels <30 g/L, preoperative APACHE II scores >20, and existing organ failure measured by the Goris score) are at high risk for developing persistent intraabdominal infection. Our data show that timely relaparotomy provides the only surgical option that significantly improves outcome. However, aggressive surgical treatment has reached its limit in patients whose source of infection could not be controlled at the initial operation. To improve overall survival the decision to perform a relaparotomy on demand after an initially successful eradication of the source of infection must be made within 48 hr, at least before MODS emerges.

Abdomen↗
PubMed1998

Hepatic resection in the elderly.

From 1986 to 1995 a total of 97 patients > 65 years of age underwent hepatic resections at the Department of General Surgery, Hospital Lainz, Vienna, Austria. The population consisted of 39 men and 58 women with a mean age of 74.0 +/- 5.5 years. Primary neoplasia of the liver was the cause of resection in 35 patients, gallbladder cancer in 16 patients, and metastatic disease to the liver (due to colorectal cancer in 70%) in 40 patients. The rate of major resections (> or = 3 liver segments) was 96% for primary neoplasia of the liver, 70% for metastatic disease to the liver, and 50% for gallbladder cancer; the associated mortality rates were 23%, 2.5%, and 25%, respectively. The magnitude of the resection had a significant influence on survival for gallbladder cancer (p = 0.02) and for primary neoplasia of the liver (p = 0.002) but not for metastatic disease to the liver. This reflects the high rate of cirrhosis in hepatocellular and cholangiocellular carcinoma (88%) and gallbladder cancer (37.5%). Both pre- and postoperative severe liver dysfunction had a significantly higher risk for postoperative mortality and morbidity, which showed an incremental risk with age. Another organ system able to predict outcome at the beginning of treatment by its moderate severe dysfunction were the lungs. Overall, only right and extended right lobectomies carried a significantly higher risk for postoperative mortality and morbidity. Postoperative complications were recorded in 43% of our patients, with infection the most frequent problem in nearly all of these patients (95%). Pneumonia was the leading complication associated patient survival. All patients who developed pneumonia as a late complication during a complicated postoperative course died postoperatively. The postoperative Goris score of the patients who died was 6.9 +/- 2.9 (range 3-11), whereas the surviving patients' score averaged 2.2 +/- 1.9 (range 0-9), which was significantly different (p = 0.0003). None of the 54 patients with a GORIS score < or = 2 died postoperatively, whereas 5 of 6 patients with a score > or = 9 died (p = 0.0001). Severe liver dysfunction rather than the extent of resection influences clinical mortality. Patients > 80 years of age with a preoperative severe liver dysfunction showed a postoperative mortality of 57%, and all of these patients developed postoperative complications. Therefore resection cannot be recommended for those patients. Cirrhosis led to an unacceptable mortality of 44% after hepatic resection of > or = 5 liver segments for primary neoplasia of the liver. Major resections cannot be recommended in the aged with gallbladder cancer because 50% of the patients died after such operations. Overall, only resection of > or = 5 liver segments with segments I to III or less remaining were found to pose a major risk for clinical mortality and morbidity, but the cause of death was preexisting liver dysfunction and cirrhosis in all of these patients. Major resections of large neoplasia of the liver can be recommended even in the aged, but a preoperative preselection of patients with respect to liver function and pulmonary function preoperatively may help lower the postoperative morbidity and mortality, especially in patients who will undergo resection of > or = 5 liver segments. Major hepatic resection for metastatic disease to the liver in the elderly carries no additional survival risk. Patients > 65 years of age and especially those > 80 years of age are more liable to succumb to postoperative organ failure and complications, especially infections.

Aged↗
PubMed1998

Cytokine patterns in patients who undergo hemofiltration for treatment of multiple organ failure.

The excessive uncontrolled activation of inflammatory cells and mediators after trauma or major surgery plays a key role in the development of adult respiratory distress syndrome and multiple organ system failure (MOSF). In the past elevated cytokine levels were shown to influence the outcome of these patients adversely. There are diverging results regarding the removal of circulating cytokines by various methods of hemopurification for clinical improvement of MOSF. Seven patients after trauma or major surgery underwent continuous venovenous hemofiltration (CVVH) for the treatment of severe organ failure of the heart and lungs (Murray score 2.74) but not for renal or liver failure. The cytokine levels were measured at the beginning and 15, 60, 120, and 240 minutes after initiation of CVVH (measure points MP1-5). Clinical improvement during the treatment was monitored, and correlation with cytokine levels was evaluated. Arterially measured tumor necrosis factor alpha rose from 11.14 ng/ml to 17.86 ng/m1 (p < 0.05). Arterial interleukin-6 (IL-6) levels significantly decreased during CVVH from 1284.7 ng/m1 to 557.9 ng/m1; IL-8 levels simultaneously decreased from an initial peak of up to 154.4 ng/m1 at MP3 to 97.3 ng/m1 at MP5. The drop in serum IL-6 and IL-8 levels closely correlated with clinical improvement. After 2 hours of CVVH the hemodynamic situation improved significantly, as revealed by a decrease in catecholamine expenditure, an increase in arterial pressure, and a decrease in pulmonary artery pressure. Moreover, 2 hours after the initiation of CVVH the oxygenation index rose significantly and correlated well with the drop in shunt fraction. The Murray score significantly fell to 1.86. The removal of IL-6 and IL-8 by CVVH after initial stimulation correlates with clinical improvement, which was demonstrated by significantly improved oxygenation and hemodynamics from 2 hours after the initiation of CVVH onward. The elimination of cytokines and several mediators by CVVH may contribute to the cardiopulmonary improvement of critically ill patients. In comparison with the clinical control group (n = 7), which was comparable in terms of MOSF, no intervention led to a similar improvement in cardiorespiratory failure, and overall two of these patients died. Moreover, patients of the control group experienced a significant longer stay at in the intensive care unit.

Adult↗
PubMed1997

Emergency surgery for colon cancer in the aged.

BACKGROUND: The prognosis of colon cancer is poorest in cases of emergency presentation of this disease in the elderly. The high rate of clinical mortality in this group of patients has made it necessary to devise a specific therapeutic approach. OBJECTIVE: To define the therapeutic approach used for colon cancer in the elderly. DESIGN: A retrospective study. SETTING: A secondary referral center. PATIENTS: Ninety-nine patients with colon carcinoma that first became clinically manifested in an emergency situation were examined retrospectively. The patients had been treated from 1986 through 1995. All patients were older than 70 years. A total of 74 patients showed clinical manifestation of a colon carcinoma with an ileus, while 10 patients had tumor perforation. A further 15 patients had a perforation proximal to an obstructing tumor. MAIN OUTCOME MEASURES: Clinical lethality, surgical procedure, risk of comorbidity, and multiple organ system failure. RESULTS: Any increase in comorbidity was associated with a higher clinical lethality, which was especially true for the lungs, heart, and kidney, and also for diabetes. In 44.4% of the patients with a significantly higher comorbidity (P = .04) and a more advanced tumor stage (P < .001), the tumor was left in situ during the primary surgical intervention. Patients who survived after staged resection had an even higher comorbidity at first presentation when compared with patients who survived after primary resection (P = .02). However, the comorbidity of deceased patients who were supposed to undergo staged resection did not differ significantly from the comorbidity of those who underwent primary resection (P = .70). The clinical lethality in patients who were managed by stoma only or by bypass anastomosis was markedly higher than that in patients who underwent primary resection (59.0% vs 43.6%). The significantly highest postoperative mortality rate was recorded in patients who underwent primary resection after colonic perforation (74%) (P = .03), while the significantly lowest postoperative mortality rate was recorded in patients who underwent primary resection after tumor obstruction (28%) (P < .001). Postoperative failure of the lungs and heart and kidney failure requiring hemodialysis were associated with significantly higher clinical mortality rates (P < .001 to P = .004). Postoperative complications occurred in 28 (28.3%) of the patients. However, rupture of the anastomosis was observed in only 2 of these patients. Generalized disease was associated with a significantly higher rate of postoperative complications (P = .04), which was especially true for pneumonia (P = .003). However, no effect on survival was found for patients with Dukes disease stage D. CONCLUSIONS: The lower mortality rate following primary resection is achieved by preselection of patients. The preselection is such that patients in poor general condition who have tumors in advanced stages are not treated by resection. The significantly (P = .03) highest postoperative mortality rate in patients who underwent primary resection after tumor perforation reflects the necessity of resection in those cases regardless of higher comorbidity. In an emergency situation, initial minimal surgery followed by staged resection is a feasible alternative to treat aged patients with a higher comorbidity and an intraoperatively established greater spread of tumor. This procedure permits delayed radical resection at the lowest rate of clinical mortality for this age group and is especially suitable for frail, aged patients in poor condition. The advantages of staged resection can be demonstrated by the fact that more patients with a higher comorbidity survive. The poor physiological adaptability of elderly patients limits their ability to compensate for postoperative organ failure and adds the risk of comorbidity. Hence, these 2 factors are associated with poor prognosis in this age group.

Aged↗
PubMed1997

Nonparasitic cysts of the liver: results and options of surgical treatment.

Nonparasitic cysts of the liver (NPHC) are highly variable in respect to appearance and therapeutic approach. The treatment of these cysts varies according to the nature and appearance of the disease. Based on the variable nature of disease and the various therapeutic options, all of which were attempted in our patients, the most suitable mode of treatment for different forms of NPHC are discussed. Ninety-one patients with NPHC who had been treated surgically from 1977 through 1995 were examined retrospectively. Asymptomatic peripheral cysts measuring up to 10 cm do not require further treatment. Computed tomography (CT)-guided aspiration (n = 9) should be regarded as a palliative measure. Within a short period, CT-guided aspiration led to recurrence of symptoms in seven of our patients. Standard treatment of NPHC is fenestration with widest possible excision of the cystic wall, which can be performed laparoscopically (n = 10) or by the conventional surgical mode (n = 54). One patient was initially operated by the laparoscopic technique but developed bleeding, which necessitated conversion to the open mode. Three patients underwent synchronous laparoscopic cholecystectomy. Recurrence rates were similar: 11% in the laparoscopically treated group and 13% in the group that underwent conventional open surgery. Conventional surgical treatment was always successful in cases of solitary cysts. However, in cases of multiple cysts measuring more than 5 cm, conventional surgery was followed by recurrence of symptoms in 26% of patients (7/27), who then had to undergo a second operation. Partial resection of the liver (n = 9) was successfully performed in cases of polycystic disease (n = 5) with concomitant enlargement of the organ as well as in cases of large solitary cysts of the left lobe of the liver (n = 4). In patients in whom we found that the cysts communicated with the ductal system (n = 3), we performed a cystojejunostomy to drain the bile. The complication rate was low. In addition to frequent postoperative ascites, which necessitated no further intervention, we observed infectious complications in four patients. Twenty patients (22%) expired during a mean follow-up period of 6.2 years. Interestingly, deaths were frequently associated with malignancy (11/20). After fenestration of multiple cysts measuring > 5 cm, the patients are at high risk for recurrence. Hence partial resection of the liver is an excellent therapeutic alternative in selected patients with polycystic disease and massive enlargement of the organ in whom the disease could not be controlled by simple fenestration. The results of this study show that laparoscopic fenestration should replace the conventional surgical technique as the gold standard in cases of NPHC because the laparoscopic technique is less stressful for the patient and is associated with a rate of success similar to that of the conventional technique.

Adult↗
PubMed1997

[Infections after liver resections in the elderly].

From 1986 to 1995, 97 patients older than 65 years of age underwent hepatic resection at the Department of General Surgery, Hospital Lainz, Vienna. The population consisted of 39 men and 58 women with a mean age of 74 +/- 5.5 years. Primary neoplasia was the cause of resection in 35 patients, gallbladder cancer in 16 patients, and metastatic disease to the liver in 40 patients. Six patients underwent hepatic resection because of benign disease. The overall rate of major resections (> or = 3 liver segments) was 73% and the overall mortality was 13.5%. Sixty-five postoperative complications were recorded in 42 patients, and infection was the leading problem in nearly all of these patients (95%). The histologic type of tumor rather than the magnitude of resection had an influence on clinical mortality and morbidity. All complications occurred in patients with malignant disease (P = 0.03). Adverse effects on postoperative morbidity were observed in adenocarcinoma of the hepatic ducts, gallbladder carcinoma, and cholangiocellular carcinoma (P = 0.003). Intraabdominal infections were found in 25% of our patients and were due to biliary leakage in 58%, but had no significant impact on survival. Pneumonia was the leading complication in association with patient survival. All patients who developed pneumonia as a late complication during a complicated course died postoperatively (P = 0.0001). All of these patients had a reduced grade of mobilization. Severe preoperative liver dysfunction carried a significantly higher risk for postoperative morbidity and mortality (P = 0.003 and 0.01), which showed an incremental risk with age > 80 (P = 0.002 and 0.0004). Right lobectomies and extended right lobectomies carried a significantly increased risk for postoperative morbidity (P = 0.004). Infection is associated with nearly every complication recorded after hepatic resection in the elderly. Pneumonia as a late complication poses a worse prognosis in elderly patients who underwent hepatic resection. Patients older than 65 years of age and especially those older than 80 years of age are more liable to succumb to complications that are predominantly infectious. Better local drainage procedures may reduce intra-abdominal infectious complications and early mobilization of the patients may improve the rate of systemic infectious complications and final outcome.

Adenocarcinoma↗
PubMed1996

Prognosis and treatment of peritonitis. Do we need new scoring systems?

OBJECTIVE: To assess the clinical significance of present scoring systems for prognosis and treatment in patients with secondary bacterial peritonitis and to define risk factors for patient survival and outcome not included in the scores. A secondary objective was to review our therapeutic regimens and the need for reoperation with regard to outcome. DESIGN: Prospective observational study. SETTING: University hospital, secondary referral center. PATIENTS: From 1992 to 1995, 92 patients with secondary peritonitis were examined at the University Surgical Clinic, Vienna, Austria. the populations as a whole consisted of 56 men and 36 women with an average age of 56 +/- 19 years. Forty-four percent of patients had postoperative peritonitis. OUTCOME MEASURES: Mortality, multiple organ system failure (MOSF), relaparotomy. RESULTS: The mortality rate in patients with an APACHE II (Adult Physiology and Chronic Health Evaluation) score of less than 15 was 4.8%, while mortality rose to 46.7% in those with a score of 15 or higher (P = .001). The average total mortality rate was 18.5%. The prognosis for patients without organ failure or with failure of one organ system was excellent (mortality rate, 0%); quadruple organ failure, however, had a mortality rate of 90%. Initial thrombocytopenia ( < 60 x 10(9)/L), four-quadrant peritonitis, and diabetes mellitus were associated with significantly higher mortality. Leukopenia (white blood cells, < 6 x 10(9)/L) and inappropriate antibiotic therapy as determined by the antibiogram were mildly significant for higher mortality. The need for relaparotomy resulted in substantially higher mortality (P < .001). The impossibility of definitive operative resolution of the intra-abdominal pathologic findings at initial operation had no significant effect on mortality, possibly because planned reoperations were always carried out in those cases. For patients with definitive resolution at initial operation, it was possible to reduce the traditionally high mortality rate associated with relaparotomy on demand by making the decision for reexploration promptly, within the first 48 hours. Nevertheless, the 52.4% mortality rate observed in those cases was still much higher than the 33% found in patients who were not free of disease after the initial operation. CONCLUSION: The prognosis in peritonitis is decisively influenced by the health status of the patient at the beginning of treatment and by any concomitant risk factors. As a result, a fairly accurate prediction of the outcome of the disease can initially be made on the basis of the APACHE II score and the MOSF score according to Goris. However, the certainty that severely ill patients with high scores often die has little clinical relevance, since it does not provide any therapeutic alternatives to the attending physician. The decision to perform a relaparotomy must be made as soon as possible, at least before MOSF emerges. Already existing MOSF will lead to the "point of no return."

APACHE↗
PubMed1996

Vascular reconstruction for limb salvage in sarcoma of the lower extremity.

OBJECTIVES: To examine the patency and limb-salvage characteristics of vascular reconstruction in patients with sarcomas of the lower extremity who had been treated with limb-preserving resection and to examine patient survival during a long follow-up period. DESIGN: Retrospective cohort study. SETTING: University hospital, tertiary referral center. PATIENTS: From 1984 to 1992, 14 patients underwent limb-preserving resection of sarcomas in the proximal lower extremity, with 20 vascular reconstructions performed. OUTCOME MEASURES: Color Doppler scans documented patency of the vascular reconstructions. Clinical evaluation included functional results in terms of limb movement and quality of life. Local tumor control and systemic recurrence were examined by repeated radiologic examination. Overall survival as well as time and cause of death were assessed. RESULTS: A total of 13 patients had patent vascular grafts, while the venous graft became occluded in 1 patient. Limb function was rated as excellent or good in 9 patients, as fair in 3, as poor in 1, and could not be clinically estimated in 1. Postoperative thrombosis of the venous graft was detected in 3 patients and was effectively managed by thrombectomy in 2. Three patients underwent reoperation because of hematoma or complications caused by local infection. The tumor endoprosthesis had to be replaced in 3 patients. During follow-up periods that ranged from 15 to 132 months (mean, 55 months), 4 patients died. In all of these patients the cause of death was systemic recurrence in the lung. Two additional patients developed pulmonary metastases, but at the time of this report, they were still alive as long as 132 months after operative resection or chemotherapy. No local recurrence was found. CONCLUSION: Limb-preserving resection of sarcoma of the lower extremity can be performed with satisfactory function of the limb maintained, even if it becomes necessary to resect the femoral vessels. Autologous venous graft for vascular reconstruction is the treatment of choice. In spite of the high incidence of metastases, considerable long-term survival is possible.

Adolescent↗
PubMed1995

[Nonparasitic liver cysts. Overview of therapy with long-term results].

Symptomatic nonparasitic cysts of the liver require surgical intervention. Seventy-one patients were treated between 1977 and 1993 at the Department of General Surgery, University of Vienna. Different surgical treatments were compared with regard to complications and recurrence. Interventional puncture led to recurrences in nearly all cases and represents only a palliative procedure. Surgical treatment consisted of either laparoscopic (n = 7) or conventional (n = 44) fenestration or excision. The rates of recurrence did not differ significantly (14% vs 9%). The laparoscopic procedure is successful not only in polycystic disease but also in solitary cysts. Wide deroofing and excision were equally effective. Laparoscopic therapy should be tried in all cysts initially, because it causes less stress than celiotomy. Because of the small number of laparoscopically treated patients in the literature and in the authors' own experience, the significance of the difference in outcome between the two methods could not be established. In more patients, further investigations should be carried out to ascertain whether the laparoscopic method is superior regarding surgical stress and recurrence. Cystojejunostomy (n = 3) and hepatic resection (n = 2) are reserved for special indications. One homologous liver transplantation was successfully carried out 6 months after cystojejunostomy because of a cholangiocellular carcinoma. Frequent postoperative ascites represented a persistent problem in only one patient. Two of three cases of postoperative infection with intraabdominal abscesses led to death. Altogether, 16 patients died, including seven because of malignancy and three because of septic complications of a Potter III syndrome.

Adult↗
PubMed1994

Intracellular pH regulation of human colonic crypt cells.

In order to investigate the regulation of intracellular pH (pHi) in freshly isolated human colonocytes, we have used a newly developed technique for the rapid isolation and covalent attachment of these cells to glass surfaces and microspectrofluorimetric measurement of the pH-sensitive fluorescence of 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein (BCECF)-loaded specimens in a perfusion chamber (37 degrees C). In N-2-hydroxyethylpiperazine-N'-2-ethanesulphonic-acid-(HEPES)-buffered Ringer solution (HBS) a baseline pHi of 7.35 +/- 0.03 (mean +/- SD; n = 42) was found for human colonocytes and in HBS, NH4Cl-prepulse-induced intracellular acidification in colonocytes is reversed rapidly by the ubiquitous amiloride-sensitive (1 mmol/l) Na+/H+ exchanger. Switching from HBS to HCO(3-)-buffered solution (BBS) led to a transient intracellular acification (7.29 +/- 0.09), followed by a recovery to a final resting pHi of 7.43 +/- 0.03. One-third of the acid extrusion in BBS is amiloridesensitive; the remaining two-thirds are caused by the dihydroderivative of 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid (H2DIDS)-sensitive HCO(3-)-dependent mechanisms. The functional activity of an acid-extruding Na+/HCO3- cotransporter in human colonocytes was observed in response to the reintroduction of Na+ into amiloride-containing Na+/Cl(-)-free BBS. In addition, the mechanism leading to alkalinization (7.56 +/- 0.05) in Cl(-)-free BBS was identified as Na(+)-dependent Cl-/HCO3- exchange, by its H2DIDS sensitivity and the specific requirement for Cl- and Na+. The intrinsic buffering capacity (beta i) of the human colonocytes was calculated from pH changes induced by sequential NH4Cl-loading steps during blockage of acid/base transporters.(ABSTRACT TRUNCATED AT 250 WORDS)

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1994

Inhibition of P-glycoprotein-mediated vinblastine transport across HCT-8 intestinal carcinoma monolayers by verapamil, cyclosporine A and SDZ PSC 833 in dependence on extracellular pH.

The ability of the multidrug resistance modifiers R- and R,S-verapamil (VPL), cyclosporine A (CsA) and its non-immunosuppressive derivative SDZ PSC 833 (PSC 833) to inhibit P-glycoprotein (P-gp)-mediated transepithelial flux of tritiated vinblastine was investigated using tight and highly resistant (R > 1,400 omega cm2) monolayer cultures of intestinal adenocarcinoma-derived HCT-8 cells grown on permeable tissue-culture inserts. Apical addition of these chemosensitizers inhibited drug flux (137 pmol h-1 cm-2; range, 133-142 pmol h-1 cm-2) in the basal to apical secretory direction at clinically relevant concentrations, with PSC 833 showing the highest activity, exhibiting inhibition at concentrations as low as 10 ng/ml (9 nM). Acidification of the modulator-containing apical compartment to an extracellular pH (pHo) of 6.8 had no influence on MDR reversal by CsA at 1 microgram/ml (0.9 microM; flux inhibition, 52%) or by PSC 833 at 100 ng/ml (0.09 microM; flux inhibition, 60%), in contrast to R,S- and R-VPL, which showed decreased inhibition and caused less accumulation of vinblastine in HCT-8 cells under this condition (flux inhibition of 35% and 23%, respectively, at pHo 6.8 vs 50% and 43%, respectively, at pHo 7.5). P-gp-mediated rhodamine 123 efflux from dye-loaded single-cell suspensions of HCT-8 cells as measured by flow cytometry was not impeded at pHo 6.8 in comparison with pHo 7.5 in standard medium, but at low pHo the inhibitory activity of R-VPL (29% vs 60% rhodamine 123 efflux inhibition) was diminished significantly, again without a reduction in the effect of PSC 833 (rhodamine 123 flux inhibition, 75%). In conclusion, drug extrusion across polarised monolayers, which offer a relevant model for normal epithelia and tumour border areas, is inhibited by the apical presence of R,S- and R-VPL, CsA and PSC 833 at similar concentrations described for single-cell suspensions, resulting in increased (2.2- to 3.7-fold) intracellular drug accumulation. Functional apical P-gp expression, the absence of paracellular leakage and modulator-sensitive rhodamine 123 efflux in single HCT-8 cells indicate a P-gp-mediated transcellular efflux in HCT-8 monolayers. In addition to its high MDR-reversing capacity, the inhibitory activity of PSC 833 is not affected by acidic extracellular conditions, which reduce the VPL-induced drug retention significantly. As far as MDR contributes to the overall cellular drug resistance of solid tumours with hypoxic and acidic microenvironments, PSC 833 holds the greatest promise for clinical reversal of unresponsiveness to the respective group of chemotherapeutics.

ATP Binding Cassette Transporter, Subfamily B, Mem↗