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PubMed1984

Learning curve for percutaneous transluminal coronary angioplasty: skill, technology or patient selection.

As with all sophisticated techniques, operators who perform PTCA show a learning curve. It can best be visualized by observing changes in success rate with growing numbers of patients. Thus, the current success rate and complication rate of a particular operator may permit an estimate of the accumulated number of patients treated by that operator. Most likely, the learning curve is also reflected in the rate of long-term success, although it may be obscured by other factors in the variable natural course of CAD. The initial steep upslope of the learning curve is mainly caused by the growing skill of the particular operator. The later, flatter part appears to be secondary to improvements in technical equipment, which take more time. Patient selection has 2 effects on the learning curve that may be self-compensating. If lessons from the past are used for selection and conservatism is preserved, the learning curve will become more pronounced.

Angioplasty, Balloon↗

PubMed1984

Intestinal vascular ectasia. Improving diagnostic capability poses therapeutic dilemma.

A case of gastrointestinal bleeding in a 73-year-old man secondary to vascular ectasia is presented. The use of the 99m technetium-tagged erythrocyte scanning to localize the bleeding site and arteriography to document a vascular malformation strongly suggested this diagnosis. Elective hemicolectomy failed to eliminate bleeding, however. Endoscopic and surgical therapies are available for this condition, but the relative frequency of postoperative rebleeding requires conservatism in recommending surgical excision.

Aged↗

PubMed1977

Conservative management of pre-eclamptic and eclamptic patients: a re-evaluation.

A philosophy of conservatism in regard to termination of gestations complicated by pregnancy-induced hypertension has been practiced at the University of Virginia Hospital for many years. The advent of improved methods to evaluate the intrauterine fetal status prompted retrospective review of 246 pre-eclamptic and 13 eclamptic patients managed during the antepartum period. Continuous magnesium sulfate infusion for periods up to 144 hours (265 grams) was the therapeutic measure used for prevention or control of convulsions. Average duration of predelivery hospitalization increased 8.7 days, and the incidence of neonates requiring intensive care increased 10.9% with the use of tests to evaluate intrauterine fetal status. Frequency of spontaneous onset of labor and vaginal delivery decreased 18.6%. The uncorrected perinatal mortality rate for all antepartum patients was 7.0%. The mortality rate for infants of mothers with superimposed, severe or convulsive disease was significantly less in pregnancies in which tests of fetoplacental status were employed (8.2%) compared to pregnancies in which they were not (15.2%). The only maternal death was a 41-year-old patient with severe pre-eclampus who suffered a cerebral vascular accident on the fifth hospital day. These data reiterate the value of conservative management with meticulous individualized care.

Adolescent↗

PubMed1978

Early vulvar carcinoma.

Fifty-eight cases of early vulvar neoplasia were reviewed from the Tumor Registry at Magee-Womens Hospital, between 1947 and 1976. Twenty-three cases were carcinoma in situ; 16 were microinvasive, and 19 were occult carcinoma. All of the cases were treated surgically. The modality of surgical treatment varied from local excision to radical vulvectomy with inguinal lymph node dissection. Regardless of the surgical therapy, none of the patients died of the vulvar malignancy. It is recommended, as part of routine gynecologic surveillance, that more critical attention be given to examination for early epithelial neoplastic lesions of the vulva. This can be accomplished by simple inspection and the use of special diagnostic aids. Biopsy specimens should be reviewed histologically for depth of invasion and the treatment individualized to the patient with considerations for conservatism, especially in younger women.

Adult↗

PubMed1979

Urinary tract endometriosis: enigmas in diagnosis and management.

The diagnosis and management of endometriosis presents several enigmas. This review, of eight patients with endometriosis involving the urinary tract, from three large clinical services in the City of Los Angeles, highlights some very difficult problems. Not only diagnostic errors but also inappropriate conservatism and inadequate surveillance have led to compromised function, resection, and/or destruction of the kidneys, ureters, or bladder. The series indicates those findings which are likely to result in urinary tract destruction and points out those clinical situations in which delays or conservative management must be undertaken only with pressing indications and then only with continued and careful surveillance.

Adult↗

PubMed1976

Combined abdominotranssacral reconstruction of the radiation-injured rectum.

Reconstruction of the rectum by a technic of combined abdominotranssacral proctocolectomy and proctocolostomy is presented as an alternative to the surgical conservatism that has been the time-honored approach to the management of radiation-injured rectum. The procedure has permitted safe accomplishment of rectal anastomosis with as little as a 1 cm distal rectal stump. Satisfactory, true anal sphincteric continence is enjoyed by six patients who have been completely reconstituted, and satisfactory reconstitution in the remaining two is anticipated. These results suggest that reinspection of the traditional approach to the radiation-injured rectum is warranted now that safe and physiologically effective reconstitution can be accomplished by a combined abdominotranssacral technic.

Abdomen↗

PubMed1978

Hydatid disease of the liver.

Our experience in the surgical management of hydatid disease of the liver in 212 patients over the past eighteen years is reviewed. The most frequent postoperative complications and mortality rates of elective and emergency procedures are presented, and the more frequently utilized operative technics are described. In the great majority of patients conservatism was the rule in excision of solitary or multiple cysts. It is important to establish whether or not hepatic cysts communicate with the biliary tree. In these cases, enteroanastomoses (such as cystjejunostomy or cystgastrostomy) may be utilized depending on the position of the cyst. Any associated biliary disease (such as lithiasis or fibrosis) should be taken care of at the same time. External cystic drainage (marsupialization) is contraindicated because of the high incidence of chronic external biliary fistula, secondary hemorrhage, sepsis, and postlaparotomy hernia. In those patients in whom the cyst has penetrated the diaphragm and communicates with the lung, treatment should be carried out in one stage whenever possible.

Adolescent↗

PubMed1986

Primary structure of chum salmon prolactins: occurrence of highly conserved regions.

The complete amino acid sequence of prolactin from the pituitaries of salmon (Oncorhynchus keta) has been determined. Salmon prolactin comprised two variants, I and II, which were separated by reverse-phase high-performance liquid chromatography. Each variant was reduced, S-carboxymethylated, and then cleaved with cyanogen bromide and enzymes. The resulting fragments were separated by reverse-phase high-performance liquid chromatography, as well as gel filtration, and subjected to sequence analysis by the dansyl-Edman method. Both variants contain 187 amino acid residues with two disulfide linkages at residues 46-160 and 177-187, lack a linkage in the N-terminal portion of mammalian prolactins, and differ from each other by the replacement of only four amino acid residues. Salmon prolactin (sPRL) shows 31% sequence identify with ovine prolactin. Moreover, four restricted regions, i.e., sPRL (3-21), (46-60), (68-83), and (160-178), encompass this significant conservatism between the teleost and the mammalian hormone, with identities of 47, 87, 62, and 68%, respectively. Such considerable identity between these distant phylogenic species strongly suggests that these regions may be responsible for the biological activity of prolactin.

Amino Acid Sequence↗

PubMed1985

Recurrence after surgery in Crohn's disease. Relationship to location of disease (clinical pattern) and surgical indication.

Among 615 patients with Crohn's disease originally diagnosed at the Cleveland Clinic Foundation from 1966 to 1969, 592 have been followed (96%) for a mean of 13 yr. Of these, 438 had undergone operation. The purpose of this study was to determine how many of these patients had developed recurrences requiring another operation and to relate recurrences to the original anatomic location of disease (the clinical pattern) and surgical indication. Those patients with ileocolic disease had the highest recurrence: 53% compared with 45% for colonic and 44% for small intestinal patterns. Second recurrences were ileocolic pattern 35%, colon 34%, small intestine 38%. The estimated median time of recurrence was similar among these three groups. The presence of internal fistula or perianal disease as an indicator for surgery were associated with a higher likelihood of recurrence and a shortened estimated median time to recurrence. This study supports the concept of conservatism with regard to the management of these two complications for patients with Crohn's disease.

Adult↗

PubMed1975

Computation of exact confidence intervals for the odds ratio.

A time-sharing program written in BASIC language has been developed to compute exact confidence limits for the odds ratio parameter in a 2 x 2 table. The program offers the user a choice between the classical exact limits and limits based upon a recent redefinition of the exact p-value aimed at avoidance of conservatism in the classical procedure. The user selects the degree of confidence desired during a run of the program, which then computes the exact limits and p-value.?23Athor

Computers↗

PubMed1991

Perianal complications of pediatric Crohn's disease.

The management of perianal disease (PD) in children with Crohn's disease was reviewed. Of 325 patients (184 boys), 200 (62%) developed PD. The mean age at diagnosis of Crohn's disease was 11.2 years (range, 5 to 17 years). Skin tags were present in 114 (35%) patients, fissures in 165 (51%), fistulas in 41 (15%), and perirectal abscesses in 47 (13%). One hundred fifty-three patients had PD as one of the first symptoms; 71 of these had complete remission of PD and the remaining 82 had chronic symptoms. Forty-two patients were initially free of PD, only to develop it later. PD occurred in 50% of patients with gastroduodenal Crohn's disease, 57% with jejunal, 68% with ileal, 64% with ileocecal, 60% with ileocolic, and 51% with colonic. Local minor operation was necessary in 38 (12%) patients, fistulotomy in 12, and abscess drainage in 26. Four patients required either intestinal resection and/or enterostomy for progressive PD. Fifty-three patients received metronidazole, with amelioration in 38. It is concluded that PD is a common complication of Crohn's disease in children and adolescents. Its presentation may antedate that of the primary disease. Most PD follows a benign course. There is a limited role for operation, but a need for meticulous perineal care and a potential benefit with metronidazole therapy. We advocate conservatism in the management of perianal complications of Crohn's disease in pediatric patients.

Abscess↗

PubMed1987

Purification and characterization of a tyrosine aminotransferase from Crithidia fasciculata.

Tyrosine aminotransferase (TAT, EC 2.6.1.5) from the kinetoplastid, Crithidia fasciculata, was purified over 2000 fold to electrophoretic homogeneity. The native form of the enzyme had a molecular weight of approximately 100,000, whereas under denaturing conditions it produced two polypeptides of approximately 50,000 and 48,000, respectively. Absence of a reaction with the periodic acid-Schiff stain suggested that the crithidial enzyme was not a glycoprotein. It was relatively stable and remained active over a wide range of pH and temperature. It exhibited a broad substrate specificity and was able to utilize L-tyrosine, L-tryptophan, and L-phenylalanine as amino donors. Antiserum produced against partially purified crithidial tyrosine aminotransferase failed to inhibit the enzymatic activity. The same antiserum cross-reacted with a soluble extract from Trypanosoma brucei gambiense, but not with that from normal mouse liver, confirming evolutionary conservatism between the two protozoa.

Animals↗

PubMed1984

Dodecandrin, a new ribosome-inhibiting protein from Phytolacca dodecandra.

Dodecandrin, a newly discovered ribosome-inhibiting protein, has been isolated and purified from the leaves of the African endod plant, Phytolacca dodecandra. Dodecandrin has a molecular weight of approx. 29 000. It cross-reacts with antiserum prepared against pokeweed antiviral protein from Phytolacca americana and exhibits similar requirements for antiribosomal activity. It is more basic than pokeweed antiviral protein, and comparison of the first 30 amino-terminal residues of the two proteins reveals 83% homology. This level of homology is greater than that between pokeweed antiviral protein and pokeweed antiviral protein S, another antiviral protein found in P. americana. Such conservatism in sequence, coupled with the high efficiency of the proteins in deactivating ribosomes and with their abundance in plant tissue, suggests that they serve an important function in the life of the plant, probably as a defense against infection.

Immunodiffusion↗

PubMed1993

Minimally invasive surgery in the Federal Republic of Germany.

In the Federal Republic of Germany 67 experts were questioned concerning the diffusion of 10 procedures in minimally invasive surgery (MIS). Most of the ten procedures have potential economic advantages and benefits for the patient. Informants state that more randomized controlled trials are needed. Extra-corporeal shock wave lithotripsy, percutaneous transluminal coronary balloon angioplasty, sclerosing of sites of upper gastrointestinal bleeding (including esophageal varices), and arthroscopic meniscectomy are well-established; laparoscopic cholecystectomy made a breakthrough in 1990. The diffusion process of the others is promising. Main obstacles to further diffusion are high investment and maintenance costs, long delivery time for special instruments, lack of systematic training in MIS, performance regulations, and conservatism. Investigations into total costs are necessary. Since the present financing of hospital services through per diem payment is detrimental to the diffusion of MIS, lump-sum payments could remove barriers to diffusion. New methods of interlinking hospital and out-patient care should be tested.

Angioplasty, Balloon, Coronary↗

PubMed1993

Diffusion of minimally invasive therapy in The Netherlands.

In the context of the European project, the diffusion of 10 selected cases of minimally invasive therapy (MIT) in the Dutch health care system was documented and analyzed. In each case the diffusion pattern resulting from the balance of stimulating and impeding factors is described, and summarized in a matrix framework. Budgetary pressures, lack of evidence on effectiveness and physician conservatism are the most important factors impeding diffusion of MIT. Patient demand, media reporting and presence of medical innovators are important diffusion-stimulating factors. Finally, a judgment is made on the policy implications of these findings, based on a comparison of the extent and speed of the diffusion of each case, the quality of evidence on effectiveness and cost-effectiveness and, in a few cases, existing policies. In most cases, more active policy making, either stimulating or otherwise guiding diffusion, would be desirable.

Angioplasty, Balloon, Coronary↗

PubMed1993

Diffusion of minimally invasive therapy in Europe.

This paper considers the diffusion of the 10 cases presented in this issue. Most of the cases have diffused relatively slowly. This slow diffusion can be explained by a number of factors, including budgetary restraints, financial incentives, physician conservatism, and lack of appropriate training. A consistent thread in the cases is the argument that evidence of effectiveness is not convincing. The article considers whether further diffusion of each innovation can be justified from existing evidence. This information is important for policy purposes. Policies might be developed to encourage or to discourage any potentially important innovation.

Angioplasty, Balloon, Coronary↗

PubMed1984

Biological modulation of the terrestrial carbon cycle: isotope clues to early organic evolution.

The characteristic difference of some 20 to 30% in the 13C/12C ratios of reduced (organic) and oxidized (carbonate) carbon as observed in the contemporary environment can be traced back over 3.5 (if not 3.8) Ga of recorded Earth history. There is little doubt that the enrichment of isotopically light carbon in fossil organic matter ultimately derives from the bias in favor of 12C during photosynthetic carbon fixation (notably the RuBP carboxylase reaction of the Calvin cycle). Accordingly, the mainstream of the sedimentary delta 13Corg record can be most reasonably explained as geochemical evidence of the isotope-discriminating properties of the principal CO2-fixing enzymatic reaction of the assimilatory pathway, thus giving eloquent testimony to an extreme degree of evolutionary conservatism in the biochemistry of autotrophic carbon fixation.

Biological Evolution↗

PubMed1992

The initiation of biological processes on Earth: summary of empirical evidence.

With the currently available geological record at band, the existence of life on this planet as from at least 3.8 Gyr ago seems so firmly established as to be virtually unassailable. Specifically, various disparate lines of evidence have merged to indicate (1) that the surface of the Archaean Earth had hosted prolific microbial ecosystems as is testified by a quasi-continuous record of microbialites ("stromatolites") and associated microfossils of prokaryotic affinity over 3.5, if not 3.8 Gyr of geological history, and (2) that the sedimentary carbon record has preserved the isotopic signature of autotrophic (notably photosynthetic) carbon fixation over the same time span. With the observed enrichment of isotopically light carbon in sedimentary organic matter largely consonant with the bias in favor of 12C during photosynthesis, the mainstream of the carbon isotope record can be best explained as geochemical manifestation of the isotope discriminating properties of the ribulose-1,5-bisphosphate (RuBP) carboxylase reaction of the Calvin cycle suggesting an extreme degree of evolutionary conservatism in the biochemistry of autotrophic carbon fixation. As a consequence, partial biological control of the geochemical carbon cycle was established already during Early Archaean times and fully operative by the time of formation of the Earth's earliest sediments.

Carbon↗