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Biomedical subjects

D Christen

Publications and source records attributed to D Christen.

At least 19 recordsLinked to original sources
PubMed2001

Gas-phase structures of acetyl peroxynitrate and trifluoroacetyl peroxynitrate.

The molecular structures and conformational properties of acetyl peroxynitrate (PAN, CH3C(O)OONO2) and trifluoroacetyl peroxynitrate (FPAN, CF3C(O)OONO2) were investigated in the gas phase by electron diffraction (GED), microwave spectroscopy (MW), and quantum chemical methods (HF/3-21G, HF/6-31G*, MP2/6-31G*, B3PW91/6-31G*, and B3PW91/6-311+G*). All experimental and theoretical methods show the syn conformer (C=O bond of acetyl group syn to O-O bond) to be strongly predominant relative to the anti conformer. The O-NO2 bonds are extremely long, 1.492(7) A in PAN and 1.526(10) A in FPAN, which correlates with their low bond energy and the easy formation of CX3C(O)OO* and *NO2 radicals in the atmosphere. The O-O bonds (1.418(12) A in PAN and 1.408(8) A in FPAN) are shorter than that in hydrogen peroxide (1.464 A). In both compounds the C-O-O-N dihedral angle is close to 85 degrees.

Journal Article↗
PubMed1998

Vibrational Information Extracted from Inertial Defects: The Complete General Valence Force Field for 1,1-Difluoroethene

The method of extracting harmonic information from inertial defect differences has been used to obtain sufficient information for a determination of the complete force field for 1,1-difluoroethylene. The presumption that inertial defect differences for non-totally-symmetric vibrations of orthorhombic molecules contain purely harmonic information (1992. D. Christen, J. Mol. Spectrosc. 151, 1-11) must be revoked, however. Copyright 1998 Academic Press. Copyright 1998Academic Press

Journal Article↗
PubMed1998

[Early postoperative nutrition after laparoscopic and open colorectal resection].

BACKGROUND: Discussions concerning postoperative nutrition were brought up again with laparoscopic colorectal surgery. We are looking whether there is any difference between open and minimal invasive procedures with respect to the start of oral intake. METHODS: In a prospective controlled trial 152 patients were analysed after laparoscopic (n = 85) or open (n = 67) colorectal resections. At the first postoperative day fluid intake was unlimited and from the second day regular food was permitted according to the patients desire. RESULTS: No influence on the beginning of nutrition was by age, diagnoses, type of operation nor their duration. Wound infection and specially cardiopulmonal decompensation prolonged lack of appetite, however, not a pneumonia. There was no increase of anastomotic leak rate. At day 4, a highly significant difference was found between laparoscopic and open surgery with 90% and 60% of patients having started regular nutrition (p < 0.001). CONCLUSION: Early postoperative oral nutrition does not increase complication rate. Patients after laparoscopic procedures start earlier eating compared with those after conventional surgery. We recommend early postoperative oral intake after both techniques according to the patients desire.

Adult↗
PubMed1997

[Rectal prolapse].

Rectal prolapse is the transposition of the entire rectal wall into the rectal lumen, the anal canal or through the anal canal out side. It differs from anal prolapse in thickness, circular plication of the mucosa and, if large, its extent. The cause is not clearly established, but disorders in bowel movement seem to be of importance. Symptoms reach from the feeling of incomplete evacuation to defecation block and irreducible prolapse. The diagnosis of outer prolapse is easy. The inner prolapse [intussusception] can be suspected by anamnesis and in the presence of solitary rectal ulcer. Defecography gives the conclusive examination. Conservative therapy is analogous to hemorrhoids: Fibres and sufficient liquid intake. Operative procedures can be divided in transabdominal and perineal procedures. From the latter Delorme's procedure gives good results with low stress for the patient. Of the transabdominal procedures we favor rectopexy with Ivalon-sponge, preservation of the lateral bands and sigmoid resection. This procedure can easily be done by laparoscopy. Postoperative constipation is observed above all if the lateral bands are dissected and no sigmoid resection is done. Preexistent constipation Improves in about 50% of the cases. Same does incontinence.

Colonic Diseases↗
PubMed1997

[Intraperitoneal tumor seeding in colorectal carcinoma surgery--follow-up of a comparison of laparoscopic versus open procedure].

Follow-up 71 patients during 20 months (12-29) operated on for colorectal cancer by laparoscopic or open surgery demonstrated no correlation between port-side metastases (1/35) or tumor recurrences (5/71) and intraperitoneal tumor cells. All these patients were cytologic-negative; however, all were initial in an advanced tumor stage (pT3-4, N1-3). We conclude from these results that free tumor cells during operation do not seem to influence outcome or the development of port-side metastases.

Adult↗
PubMed1996

[Technique and results of laparoscopic rectum resection].

The general principles of oncologic operations for colorectal cancer are the same for both open and laparoscopic surgery. Isolation of the tumor by occlusion of the intestinal lumen, early blockage of venous outflow, complete resection of the lymph node bearing mesenterium, high ligation of the artery and prevention of tumor cell dissemination during extirpation of the specimen are the most important factors. We present our technique for laparoscopic abdominoperineal resection, which fulfills the above mentioned criteria. From June 1993 to October 1994 we operated on 19 patients (median age 68 [47-91] years; male/female ratio 10/9). Laparoscopic abdominoperineal resection of the rectum was palliative in 3 patients and curative in 16. Tumors were located 3 (1-8) cm from the anal verge. In 3 patients the operation was converted to open surgery. Intraoperative complications were encountered in 3 patients. Median operation time was 300 (200-400) minutes and postoperative morbidity 8/19 (42%) leading to reoperation in one patient. 30-day mortality was nil. Three patients died 5, 8, and 14 months postoperatively due to metastatic disease (all 3 after initial palliation). One patient had local recurrence and liver metastasis and died 14 months after operation. Another patient died from liver metastases. In one patient a single liver metastasis was successfully removed. 14 patients were tumor-free after a median follow-up of 10 (3-14) months. There was no implantation metastasis on a trocar site. Laparoscopic abdominoperineal resection of the rectum is feasible and the results are comparable with those of open surgery. Local recurrence rate and incidence of liver metastases are comparable with open surgery after this short follow-up. However, 5-year survival is needed to judge the oncological radicality of laparoscopic abdominoperineal resection of the rectum.

Adenocarcinoma↗
PubMed1996

[Tumor cells in peritoneal irrigation fluid in conventional and laparoscopic surgery for colorectal carcinoma].

BACKGROUND: In minimal invasive cancer surgery port-side metastases are observed. The most plausible theory of there development is by tumor cell contamination during the operation. This prospective controlled study was designed to evaluate the moment of liberation of cancer cells, frequency of implantation and follow up after laparoscopically assisted and open resections. METHODS AND PATIENTS: The peritoneal cavity is washed out 4 times with 200 mls of Ringer' solution (at the beginning of the operation, after central ligation of the vessels, after mobilisation of the cancer and at the end). The aspirate is centrifuged and stained by Papanicolaou. Follow up is by the protocol of the swiss cancer study group. Up to now 71 patients (35 laparoscopical, 4 conversions, 27 open, 5 peritoneal carcinomatosis) have entered the study. RESULTS: Positive cytology was found in 4/35 laparoscopic and 5/27 open resections. Excluding the first wash out 1/35 (3%) and 3/27 (11%) respectively were positive, however, none at the end of operation. Only in 4/5 peritoneal carcinomatosis tumor cells were present in the final wash out. Median follow up of patients with positive cytology was 9,5 months [6-15] for laparoscopy and 8 months [2-11] for open surgery. Three from each group were followed more than 7 months. No recurrence or port-side metastasis was observed. In patients with negative cytology two cancer progressions were detected. DISCUSSION: The significance of free tumor cells for the development of implantation metastases is unclear. In 8/13 patients cytology was positive at the beginning of the operation, and only patients with a peritoneal carcinomatosis demonstrated cancer cells in the final wash out. In laparoscopy no cells were found in the second and one in the third wash out, resulting in a 1/35 risk of cancer cell liberation. Whether this patient will develop a port-side metastasis is unknown. He is followed for 8 months without tumor progression. We believe that a positive cytology alone cannot be the reason for implantation metastases. CONCLUSION: Using the minimal invasive technique for colorectal carcinoma resection liberation of cancer cells tends to be less compared with open surgery. For further conclusions the time of follow up is not yet long enough.

Adult↗
PubMed1996

[Sources of hazards in laparoscopic colon surgery and how to avoid them].

From May 1993 to September 1994 98 patients with colon pathology were operated with the laparoscopic method. Criteria for exclusion were: patient's wish, tumor size or tumor infiltration in adjacent organs. The resection was carried out strictly according to the guidelines of open surgery. All operations were performed by two laparoscopically experienced visceral surgeons. All routine colon operations were included. The conversion rate was 13%. The rate of anastomotic leakage was 3.5% in both laparoscopic completed resections as well as in left-sided resections, which is comparable to the rate found in open resections. The rate of stenosis, showed a similar finding amounting to 3.5%. A complication subject to laparoscopic surgery occurred in one of our early cases, namely the severing of the ureter, this complication can be avoided with sufficient experience. Furthermore a portside hernia (1.2%) was due to laparoscopy and can be avoided as well by accurate suture of the trocar incisions. Initial postoperative hemorrhage (n = 4, one of which required operative revision) were no longer observed with increasing experience and careful choice of the trocar incision sites. An initially increased rate of wound infections could be reduced substantially by using a wound-protecting device during surgery. Laparoscopic colon resection is a safe method, which has a reduced rate of relevant complications in comparison to open procedures. Prerequisite for success is optimal technical equipment, an experienced and well coordinated team, and the understanding that conversion to an open procedure is not to be considered a complication.

Adult↗
PubMed1996

[Intraperitoneal tumor seeding in colorectal carcinoma surgery--a comparison of laparoscopic versus open procedures in a longitudinal study]].

Tumor cell spread during laparoscopically assisted (n = 35) and open (n = 27) resections of colorectal cancer or patients with peritoneal carcinomatosis (PC) (n = 5) was studied by repeated lavage. Positive cytology was found in 3% during laparoscopy, 11% during open surgery and 80% in PC. We conclude that the risk of cancer cell mobilisation is minimal in laparoscopic surgery.

Adult↗
PubMed1995

[Does laparoscopic colonic carcinoma surgery satisfy the radicality criteria of open surgery?].

Minimal invasive surgery is applicable to almost all colorectal operations, with major benefit for the patient. Technically even cancer operations can be performed. However, in laparoscopic assisted colorectal surgery the question of radicality outweighs that of performability and patient comfort. From a prospective series of 88 laparoscopic colorectal operations, 36 were for carcinoma. 34 patients who underwent conventional surgery were matched with regard to age, sex, type of operation and tumor stage (TNM, grading) to compare the two techniques. The two interventions followed exactly the same guidelines. We compared the length of the fixed specimens, the number of resected lymph nodes and the need for blood transfusions. Postoperative complications were noted and follow-up was 3-12 months. The data obtained showed no difference between the two treatment groups, with a slight trend towards laparoscopic surgery with regard to number of resected lymph nodes. A portside metastasis was observed 9 months after an initial tumor stage T4N1M1. The close relation between the portside and infiltration of the adenocarcinoma into the abdominal wall together with a drain placed through this whole was suspected to be the cause of this complication. We conclude that laparoscopic assisted colorectal surgery for cancer is equal to open operation regarding radicality of resection. Long term results are mandatory to determine the value of minimal invasive surgery in the field of oncology.

Adult↗
PubMed1995

[How safe is laparoscopic colon surgery?].

Like any new technique, laparoscopic colon surgery must display results of the same or even better quality than established methods. In this hospital every laparoscopic colon operation has been registered since 1993. Patients were informed orally or in writing that the laparoscopic procedure is a new surgical technique and that, in particular, long term results in colon carcinoma are lacking. Patients who did not undergo the laparoscopic method were those who did not agree to this type of surgery, had tumor infiltrations without extensive liver metastases, or tumor sizes where laparotomy to retrieve the specimen is not much smaller than the open surgery incision. All operations without exception were performed by two laparoscopically skilled abdominal surgeons. We used four 12 mm Troicarts placed in a diamond position, the criteria for mobilization and resection strictly following those of open surgery. In rectosigmoid resection the specimens were extracted suprapubically, with simultaneous implantation of the anvil, in the other cases at appropriate sites. The anastomoses were created either by the double stapling technique or with a single layer running suture. 88 patients underwent operation. The change to open surgery was 11%. The reasons for the change were chiefly inflamed, bleeding diverticulitis tumor, carcinoma infiltrations and, in one case, bleeding. The anastomosis failure rate of the descendorectostomy, and in all laparoscopic colon operations, was 4% and compares favourably with the literature. This was also true of stenosis incidence. The wound infection rate is on the whole the same as for open surgery. The complication in the descendorectostomy is reduced by half in the laparoscopic procedure.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Randomized comparative trial of imipenem/cilastatin versus aminoglycoside plus amoxycillin plus clindamycin in the treatment of severe intra- and post-operative infections.

In a prospective, randomized, controlled study, clinical and bacteriological efficacy of imipenem/cilastatin (I/C) was compared with a standard combination of aminoglycoside + amoxycillin + clindamycin (C) in patients (pts) with severe intra- and postoperative infections. A total of 84 pts were randomly separated into two groups of 42 pts. Diagnoses were pneumonia n = 21 (14 in I/C group and 7 in C), peritonitis n = 45 (16 in I/C group and 29 in C), septicaemia n = 12 (9 in I/C group and 3 in C), and 7 other infections (3 in I/C group and 4 in C). Doses used were imipenem/cilastatin 1 g q 8 h and amoxycillin 2 g q 8 h plus clindamycin 0.6 g q 6 h, plus netilmicin according to serum concentrations. Success rates were 85.4% (n = 35: 34 cured and one improved) in the I/C group and 83.3% (n = 35: 30 cured and five improved) in the C group. Six pts in group I/C and 7 in group C failed to respond to treatment. One patient in the I/C group was not assessable. 62% of the bacterial isolates were eradicated in the I/C group and 55% in group C. 7% were suppressed in I/C and 5% in C. It is concluded that imipenem/cilastatin is an effective and well-tolerated alternative to antibiotic combinations in severe intra- and post-operative infections. It offers the advantages of fewer drug doses and less renunciation of serum drug concentration monitoring.

Aminoglycosides↗
PubMed1992

[Anal condylomata acuminata in HIV positive patients].

Since July 1986 we started with following all patients with condylomata acuminata including HIV-testing and human papilloma virus (HPV) identification by DNA-DNA-hybridisation (southern blot). Seventy patients are included, 39 of them are seropositive. The ratio male to female is 59 to 11, in seropositives 35 to 4, in negatives 24 to 7. The average age is 28 and 31 years respectively. The number of homosexuals and junkies is significantly higher in seropositives. Seventeen patients are in HIV-stage II, 11 in stage III and 10 in stage IV according to CDC-classification. Characteristic for the seropositives was an extensive growth on the rectal mucosa and the very rapid growth of initially subtotally resected lesions in order to prevent stenosis. Sixty-five patients were treated by one stage radical operation with electrocauter. Surprisingly recurrency is more frequent in seronegatives, however, the lesion is much smaller in this group. A hypothesis to explain this observation is brought forward. Postoperative complications occurred only in HIV-stages III and IV. We therefore recommend single shot antibiotic prophylaxis in these patients. The HPV-identification showed no malignancy associated HPV-types in both groups but a higher incidence of HPV 11 in higher HIV-stages which we cannot explain. We conclude from our series that, if operation is indicated, one stage radical electrocoagulation of condylomata acuminata is a necessary procedure in seropositive patients and a save one in negative patients but antibiotic prophylaxis should be given in stage III and IV. Anal condylomata acuminata are a hint for possible HIV-positivity.

Adolescent↗
PubMed1991

Peritoneal adhesions after laparotomy: prophylactic measures.

Abdominal adhesions are due to a locally decreased peritoneal fibrinolytic capacity occurring mainly in ischemic areas of the peritoneum. They help to guarantee the supply of blood to these areas, acting as a protective mechanism ("vascular graft"). With respect to abdominal surgery a general suppression of the ability to form adhesions would therefore seem to be questionable. We consider the currently employed or discussed methods with their advantages and disadvantages. No optimal solution to the problem of adhesions has been found so far. Nevertheless, appropriate surgical technique can permit us to control adhesion formation to a certain degree. If adhesions are unavoidable, placement of the greater omentum should be done carefully in the areas of risk.

Humans↗
PubMed1991

[Anal condylomata acuminata. A prospective comparison of HIV positive and negative patients].

Between July 1986 and May 1987 23 patients suffering from anal condylomata acuminata were treated at the University Hospital of Zurich. The influence of HIV-infection on the disease is described. An almost equal frequency of recurrencies between positives and negatives was observed in a three year follow-up time. However, in positive patients recurrence was earlier and much more extensive. A two-stage procedure which sometimes is advocated in very extensive lesions gave very bad results in HIV positives. We use a radical excision by electrocoagulation on the mucosa and perianally and avoid circular necrosis in the lower anal canal only. Infectious complications are not to be feared except in patients with symptomatic HIV-infection resulting in the recommendation for a antibiotic prophylaxis in such cases.

Anal Canal↗
PubMed1990

Antimicrobial management of postoperative infections in abdominal surgery: single or combination regimen?

In a prospective, controlled, randomized study, the clinical and bacteriologic efficacy of imipenem/cilastatin was compared with that of a standard combination of an aminoglycoside, amoxicillin, and clindamycin in patients with serious postoperative infections. Doses used were imipenem/cilastatin 1 gm q 8 hr, amoxicillin 2 gm q 8 hr, and clindamycin 0.6 gm q 6 hr. Aminoglycoside doses were individualized and monitored six times weekly with serum concentration assays. Sixty-three patients were entered into the study: 31 in the imipenem/cilastatin group and 32 in the combination group. Diagnoses included pneumonia (ten in the imipenem/cilastatin group and seven in the combination group), peritonitis (eight in the imipenem/cilastatin group and 15 in the combination group), and septicemia (eight in the imipenem/cilastatin group and three in the combination group). The two groups were comparable with respect to sex, age, underlying diseases, and duration of antibiotic therapy. In the imipenem/cilastatin group, 26 patients were cured and one improved (87%). In the combination group, 21 were cured and five improved (81%). Four patients receiving imipenem/cilastatin and six receiving the combination therapy failed to respond to treatment. Eighty percent of the bacterial isolates were eradicated, and 15% were suppressed in the imipenem/cilastatin group. Corresponding frequencies in the combination group were 84% and 11%, respectively. Isolated pathogens persisted in 5% of the patients in each group. It is concluded that imipenem/cilastatin appears to be an effective and well-tolerated alternative to a triple antibiotic combination in the treatment of serious postoperative infections.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdomen↗