Reverse diel vertical migration: an escape from invertebrate predators.

The marine copepod Pseudocalanus sp. exhibits an unusual reverse diel vertical migration in Dabob Bay, Washington, concurrently with a normal vertical migration by nocturnal invertebrate predators. Reduced spatial overlap with predators appears to decrease mortality rate of adult female Pseudocalanus. A life table analysis suggests that the demographic disadvantage associated with daily migration across a thermal gradient can be overcome if mortality is reduced by as little as 16 percent.

A rapid and improved method for generating cDNA libraries in plasmid and phage lambda vectors.

We have developed a fast and efficient procedure for generating cDNA libraries in plasmid or phage lambda vectors. We used Mo-MuLV reverse transcriptase to synthesize the first strand and directly added Escherichia coli DNA polymerase I with RNase H to synthesize the second strand. A special advantage of our procedure is the use of oligodeoxynucleotide adapters to insert the cDNA into the vector, avoiding the use of methylating enzymes and subsequent digestion with massive amounts of restriction endonucleases. This also obviates the need to tail the cDNA molecules with homopolymers, simplifying subsequent procedures such as sequencing or transfer to other vectors. Finally, we have used a rapid screening procedure to isolate full-length clones with oligodeoxynucleotide probes recognizing conserved regions at the 5' termini of the mRNA. The system is ideal for cloning and analyzing polymorphic alleles of genes, such as those of the major histocompatibility complex.

Cutaneous complications in renal transplant recipients.

Systematic review of the histologic characteristics of skin lesions biopsied and/or resected in a group of 580 renal transplant recipients collected over a 16-year period showed a total of 170 specimens from 120 patients. In this group there were 41 benign tumors, 22 infections, 35 inflammatory dermatoses, and 13 miscellaneous lesions. Fifty-nine lesions were malignant, and half of these were squamous cell carcinomas (SCCs). None were lethal or metastasized, although deeply invasive local recurrences and multiple lesions were common. Comparison with SCCs from a control group showed no clearcut differences with respect to level of invasion, grade, pattern, or presence of actinic change. Most of these lesions were found in sun-exposed areas, were associated with actinic changes, and with actinic keratoses. Problems in differentiating SCC from keratoacanthoma and the clinical implications of these difficulties are discussed in conjunction with a review of the literature.

Gastrointestinal complications in renal transplant recipients.

In a 16-year study, 101 gastrointestinal (GI) lesions (16 fatal) developed in 580 renal transplant recipients seen in the authors' institution. Lesions were seen at all levels of the GI tract, but colonic lesions were the most common (42 patients) and were fatal in 8. Segmental ischemic colitis was the single most common morphologic diagnosis (14 patients). Seven of these patients had an unusual syndrome that clinically, at surgery, and on gross examination resembled inflammatory bowel disease. Lesions were segmental; involved bowel was thickened and erythematous with creeping peritoneal fat. Histologically, mucosa adjacent to the frank necrosis showed simplification and striking epithelial atypia. Specific identifiable viral infections caused 28% of the GI complications in this series. This incidence is higher than that in other reported series. Most of these infections can be diagnosed from endoscopically obtained material. These findings have therapeutic implications.

Unexpectedly high incidence of cytomegalovirus infection in apparent peptic ulcers in renal transplant recipients.

Gastroduodenal ulcers in renal transplant recipients are usually accepted as being acid-peptic in origin. In a series of 573 renal transplant recipients there was histologic material available for examination from eight patients with gastroduodenal ulcers and three patients with gastric erosions. All ulcers had originally been diagnosed as peptic or stress ulcers. However, on review, five of them proved to contain cytomegalovirus (CMV); CMV was also present in all the stomachs with erosions. We suggest that CMV infection plays as important a role in upper gastroduodenal ulcers and erosions in renal transplant recipients as it does in similar lesions elsewhere in the gastrointestinal tract of these immunosuppressed patients.

Use of the internal jugular vein for carotid patch angioplasty.

The internal jugular vein is an excellent source of autogenous tissue for carotid artery reconstruction because of its availability in the operative incision, adequate size, and ability to be harvested without morbidity. For 153 of 453 consecutive carotid reconstructions, the durability of the internal jugular vein (n = 76) and the greater saphenous vein (n = 77) as a patch angioplasty was compared. Mean postoperative follow-up was 17 months (1 to 52 months). The vein-patched carotid-bifurcation was studied by means of duplex ultrasonography to assess patency, detect restenosis, and measure cross-sectional diameter during systole. No carotid bifurcation occluded after operation. No ruptures or aneurysmal dilatations of the vein patches were observed. The maximum diameter (mean +/- SD) of the carotid patch angioplasties constructed with internal jugular vein (9.4 +/- 1.9 mm) was similar to patches made with greater saphenous vein (9.6 +/- 1.7 mm). In 95 patients serial duplex examinations demonstrated maximum diameter changes of the vein-patched internal carotid artery ranging from an increase of 3.5 mm to a decrease of 3.0 mm. Asymptomatic restenosis (greater than 50% diameter reduction) was detected in 2/95 (2.1%) patients. Because of the premium placed on the saphenous vein for peripheral arterial reconstruction and coronary artery bypass grafting, the ipsilateral internal jugular vein should be used more frequently for carotid patch angioplasty.

Allergic contact dermatitis in children and young adults.

We evaluated the results of a 5-year period of epicutaneous testing in children and teenagers younger than 16 years of age. In an overall-tested population of 2671 persons, 67 were younger than 16 years. In 16 (23.8%) of these 67 children, a positive epicutaneous test was considered to be clinically relevant for the diagnosis allergic contact dermatitis. From the total of 44 positive tests, the most common allergen was nickel sulfate (18%), followed by balsam of Peru, Carba mix, colophony, and fragrance mix (6% each). As our test population consisted of only a few children, no conclusions were drawn in respect to children younger than 10 years. Despite our careful selection of children with allergic contact dermatitis, the prevalence of positive epicutaneous tests was no different than that reported for unselected populations of children.

The use of low molecular weight heparins for the prevention of postoperative venous thromboembolism in general surgery. A survey of practice in the United States.

BACKGROUND: Even though low molecular weight heparins (LMWHs) have become the standard for venous thromboembolism (VTE) prophylaxis in most European countries and Canada, it was not until recently that LMWHs were approved for use in the United States. The main objective of this study was to assess the current preferences and attitudes of United States surgeons toward the prevention of VTE with particular reference to LMWH. METHODS: A survey with questions relative to VTE awareness, risk factors, and prevention practices was mailed to 10,000 Fellows of the American College of Surgeons. RESULTS: A total of 1,145 (11.45%) usable questionnaires were returned. The vast majority (96%) of respondents use prophylaxis against VTE. Although LMWHs were rated first regarding efficacy and second regarding simplicity of use, conventional unfractionated heparin at fixed doses remains the preferred pharmacological agent for VTE prevention (74%), followed by 2 LMWHs: enoxaparin (34%) and dalteparin (16%). Overall, 52% of surgeons preferred physical methods over pharmacological methods when used separately and 26% of surgeons utilize combined physical-pharmacological modalities. CONCLUSIONS: North American general surgeons have substantially modified their approach to VTE prevention in the last 4 years. Physical methods and unfractionated heparin remain the preferred prophylactic modalities, but LMWHs have gained rapid acceptance since their approval for use for VTE prevention in North America. Even though the results of this survey must be interpreted with caution because of the limited response rate and possible sampling bias, they still reflect the current preferences and attitudes of North American surgeons toward prophylaxis.

[Acne vulgaris in connection with the use of progestagens in a hormonal IUD or a subcutaneous implant]. / Acne vulgaris bij gebruik van progestagenen in een hormoonspiraal of een subcutaan implantaat.

Three women developed severe acne vulgaris within several weeks to a few months after either insertion of a levonorgestrel IUD (two women, 27 and 33 years of age) or subcutaneous implantation of an etonogestrel implant (26-year-old woman). The first woman had had acne previously; her IUD was removed and she was transferred to oral contraception with cyproterone-ethinyloestradiol. The second woman was treated with a peeling cream. The third woman changed to an oral anticonceptive and was treated with isotretinoin. The acne disappeared in all three patients. Progestagens have androgenic activity, even in low doses, and it is well known that androgenic stimulation of the sebaceous glands can cause acne vulgaris. The possibility that acne vulgaris may be an adverse reaction is probably not always considered. When asking the patient about her use of drugs, one should therefore ask specifically about an IUD or a subcutaneous implant.

Villous tumors of the duodenum: a clinicopathologic study.

Eight villous tumors of the duodenum were found and studied in a review of surgical and autopsy material collected over 30 years. Although the number of cases is small, it is nevertheless one of the largest single series on this lesion that has been reported. The purposes of the study were (1) to describe the histopathology of the lesions and (2) to test the diagnostic criteria of malignancy previously proposed in the literature. Of the large number of criteria studied, none, alone or in combination, proved reliable indicators of malignancy; even in this small series exceptions could be found. Of all the criteria tested, however, secondary gland formation was found to be the most reliable. The value of endoscopic biopsies in establishing the preoperative diagnosis of malignancy in this lesion seems to be analogous to that in similar colonic lesions. Prognostic and therapeutic criteria are discussed. In addition, the pertinent literature is reviewed.

Primary hepatocellular carcinoma following nonspecific non-B hepatitis with tumor DNA negative for HBV DNA.

An association between non-A, non-B hepatitis and hepatocellular carcinoma has been made on the basis of negative serological markers for hepatitis B virus (HBV); however, hepatocellular carcinomas have been found to contain hepatitis B virus deoxyribonucleic acid (HBV DNA) in individuals who lack serological markers of HBV infection. Therefore, reports which ascribed a hepatocellular carcinoma to non-A, non-B hepatitis but did not examine the tumor for HBV DNA are open to question. We describe a case of chronic active hepatitis with primary hepatocellular carcinoma that lacked HBV DNA in the tumor, the nontumorous liver tissue, and serum. The individual lacked all serological markers for HBV infection. This report more fairly supports the association between hepatocellular carcinoma and chronic hepatitis not due to hepatitis B. Whether this is related specifically to a non-A, non-B hepatitis agent requires identification of the viral agents that cause non-A, non-B hepatitis.

Transvenous liver biopsy in critically ill patients: adequacy of tissue samples.

In a consecutive series of 33 patients (38 biopsies), the authors analyzed the pathologic specimens obtained with their relatively new transvenous biopsy method. From the point of view of establishing a useful pathologic diagnosis, the method proved worthwhile in the series of predominantly critically ill patients. A specific diagnosis or a later confirmatory tissue diagnosis was achieved in 18 patients, and a strong clinical correlation was achieved in 10 more. There were no complications from this repeatable, technically relatively simple, and safe procedure.

Warm ischemic damage to the epiphyseal growth plate: a rabbit model.

Warm ischemic growth plate damage was produced in the hindlimbs of 33 New Zealand white rabbits, who were 7 weeks old, by isolating the knee joint on a popliteal vascular pedicle. Zero, 3, 7, and 12 hours of warm ischemia were produced by pedicle occlusion. The 0- and 3-hour ischemic groups showed mild growth disturbances related to the surgical model and were not statistically different at 90 days postoperatively. The 7- and 12-hour ischemia groups showed severe growth disturbances and were statistically different from the 0- and 3-hour groups at all periods measured (p less than 0.05). Large central growth plate lesions were apparent by histologic examination. Twelve hours of ischemia produced a histologic picture identical to growth plate infarction. Increased warm ischemic time correlated with more severe growth retardation and evidence of increased damage to the central area of the growth plate histologically.

Liver biopsy versus ultrasound in methotrexate-treated psoriasis: a decision analysis.

Before starting methotrexate therapy for cases of recalcitrant psoriasis, a liver biopsy has been usual in order to exclude cirrhosis and moderate or severe fibrosis, which are contraindications for methotrexate treatment. As mortality and morbidity of liver biopsy are not negligible, and as this invasive procedure is unpleasant for the patient and urges clinical admission, we evaluated the possibility of ruling out severe liver pathology by means of ultrasonography, which we compared to liver biopsy. We made this comparison by means of a decision tree. The advantages of this analysis are the clear definition of the decision problem and its alternatives, and the possibility of calculating the risk of each alternative, thus being able to choose the best diagnostic method. In this study, the results of various research groups are discussed, in which liver biopsy and liver ultrasound were compared. In our decision tree we used some of these results and other assumptions, based on comparable studies. We varied the biopsy mortality and the sensitivity of ultrasound to show the change in the risk of each alternative. Our analysis shows that the differences of expected values between the liver biopsy branch and the ultrasonography branch are relatively small. Therefore, we advise each center, which has at its disposal a specialist in liver ultrasonography, to re-evaluate its guidelines with regard to the detection of severe liver pathology before starting methotrexate for the treatment of psoriasis.