Cascading speciation among mutualists and antagonists in a tree-beetle-fungi interaction

Cascading speciation is predicted to occur when multiple interacting species diverge in parallel as a result of divergence in one species promoting adaptive differentiation in other species. However, there are few examples where ecological interactions among taxa have been shown to result in speciation that cascades across multiple trophic levels. Here, we test for cascading speciation occurring among the western pine beetle (Dendroctonus brevicomis), its primary host tree (Pinus ponderosa), and the beetle's fungal mutualists (Ceratocystiopsis brevicomi and Entomocorticium sp. B). We assembled genomes for the beetle and a fungal symbiont and then generated reduced representation genomic data (RADseq) from range-wide samples of these three interacting species. Combined with published data for the host tree, we present clear evidence that the tree, the beetle, and the fungal symbionts are all genetically structured into at least two distinct groups that have strongly codiverged with geographical isolation. We then combine our genomic results with diverse population and laboratory-based data to show evidence for reproductive isolation at each level of the cascade and for coevolution of both antagonistic and mutualistic species interactions within this complex network.

Laparoscopically assisted colon surgery

Laparoscopy has been used in surgical procedures more frequently in the past decade because it reduces postoperative pain, decreases the length of hospitalization, decreases the duration of disability, and provides a better cosmetic result. We retrospectively reviewed our experience with laparoscopic colon surgery at Baylor University Medical Center. Since 1995, we have done 17 procedures, including 10 colon resections and 7 colostomies. The results in these patients have been quite good: only 1 patient was converted to an open procedure, and the remaining 16 patients experienced no mortality, major morbidity, or wound infection.

Laparoscopic Nissen fundoplication for gastroesophageal reflux disease

BACKGROUND

This is a retrospective review from March 1994 through October 1996 of 78 patients who underwent laparoscopic Nissen fundoplication for gastroesophageal reflux disease (GERD). The purpose of this study was to evaluate the postoperative results and complications.

METHODS

The patient profile included 38 men and 40 women with a mean age of 46 years (range 11 to 81). The main preoperative symptoms included heartburn (92%), respiratory problems (42%), and dysphagia (32%). Preoperative assessment included esophagogastroduodenoscopy, upper gastrointestinal series, esophageal manometry, and 24-hour pH monitoring. Essential indications for surgery included esophagitis (83%), Barrett's esophagus without dysplasia (22%), and esophageal stricture (23%). All patients underwent a 360-degree wrap with a Maloney dilator and division of the short gastric vessels.

RESULTS

The mean operative time was 206 minutes (range 90 to 455). The average time for patients to tolerate a full liquid diet was 1.2 days, and the mean hospital stay was 2.4 days. Current follow-up, from 3 to 36 months, showed complete resolution of heartburn without medications in 67 patients (86%), occasional heartburn in 8 patients (10%), and slight improvement of heartburn in 3 patients (4%). Five patients with preoperative Barrett's metaplasia showed no evidence of it postoperatively (n = 2) or marked regression (n = 3).

CONCLUSION

Laparoscopic Nissen fundoplication is the procedure of choice for patients with complicated GERD.

Single-chain recombinant human cytomegalovirus protease. Activity against its natural protein substrate and fluorogenic peptide substrates

We report here the production of active recombinant single-chain human cytomegalovirus protease in Escherichia coli and development of a continuous assay for this protease. In order to produce the human cytomegalovirus (HCMV) protease for structural studies and accurate kinetic analysis, mutation of alanine 143 at an internal cleavage site was introduced to prevent auto-proteolysis. The resulting soluble 29-kDa A143Q protease was purified to homogeneity as a stable single-chain protein by hydrophobic interaction and ionic-exchange chromatography. The in vivo protein substrate, assembly protein precursor, was also expressed and purified for activity studies. To develop a continuous protease assay, fluorescent synthetic peptide substrates similar to the cleavage sequence P5 to P5' of the maturation site containing anthranilic acid and nitrotyrosine as a resonance energy transfer donor-acceptor pair were designed. Purified HCMV A143Q protease cleaved the recombinant assembly protein precursor with Km and kcat values of 3.0 +/- 1.0 microM and 13.3 +/- 1.6 min-1. The Km for peptide substrates is at least 45-fold higher than for the natural protein substrate, but the kcat values are similar. A sensitive assay was developed using fluorescent peptide substrates, which can detect nM HCMV protease activity.

Synergy between preactivated photofrin-II and tamoxifen in killing retrofibroma, pseudomyxoma and breast cancer cells

Exposure of photoactive compounds to light prior to their use in biological systems (preactivation) results in the generation of tumour cell specific metastable cytotoxic species that are no longer dependent on the light energy. Thus, preactivation renders the photoactive compounds suitable for systemic use. We have examined the in vitro effect of preactivated photofrin-II and tamoxifen in retroperitoneal fibroma, pseudomyxoma and male breast carcinoma cell lines. These cells were found to be non-responsive to tamoxifen and were negative for oestrogen receptors. Incubation of these cells with 0.5 microgram/ml preactivated photofrin-II and tamoxifen (less than 10(-6) mol/l) resulted in a significantly enhanced (P less than 0.001) inhibition of DNA synthesis compared with either agent alone. This synergistic effect between tamoxifen and preactivated photofrin-II was determined by multiple drug effect analysis. Treatment of cells with preactivated photofrin-II did not cause the increased expression of oestrogen receptors. These observations suggest that a combination of antihormonal drugs with preactivated compounds may be of clinical value.

The response of retroperitoneal fibrosis to tamoxifen

Although retroperitoneal fibrosis is uncommon and histologically benign, it is a progressive and potentially fatal tumor. As the fibroblasts proliferate, they encase and may obstruct important retroperitoneal structures. Medical therapy in the past has been ineffectual, and since the tumor usually cannot be resected, surgery consists of lysis or bypass of the involved structures. Tamoxifen is effective in the treatment of desmoid tumors, and we report its use in two patients with retroperitoneal fibrosis with excellent results. The simplicity and safety of this treatment make tamoxifen an attractive choice of therapy.

Biliary lithotripsy

At Baylor University Medical Center in Dallas, we began performing lithotripsy with the Medstone STS lithotripter for gallstones in January 1988 and in the first year treated 81 patients. Fifty-five of these patients were available for 4-month follow-up. We randomized half of the patients to receive ursodeoxycholic acid for 7 days prior to lithotripsy and gave all of the patients ursodeoxycholic acid after lithotripsy. Only 10.4 percent of the patients who contacted us ultimately proved to be candidates for lithotripsy. Gallstone fragmentation occurred in 95 percent of all patients and in 97 percent of those patients with solitary stones under 20 mm in size. The rate of clearance for solitary stones less than 20 mm in size was 50 percent. Unfavorable effects ascribable to lithotripsy were infrequent. All of the patients had pain before treatment, and one-third complained of biliary colic after treatment. Minor skin bruising which resolved in 1 to 5 days was found in 20 percent of the patients. This study lends credence to the findings of previous studies and demonstrates that lithotripsy combined with bile acid therapy is a useful therapy for cholelithiasis.

Biliary lithotripsy in the United States

We have reported the case of a patient whose gallstone was completely fragmented by lithotripsy; all demonstrable particles passed completely within 36 hours. The patient required no analgesics and had no complications from the procedure. This is the first case of gallstones successfully treated solely by a combination of lithotripsy and bile acid therapy in the United States under an FDA-approved IDE protocol.

Cholecystectomy

We retrospectively reviewed 360 consecutive cholecystectomies done by the four surgeons in our private group practice. No patient had dehiscence of the wound or evisceration. One patient had a seroma, which was opened in the office, but the fluid contained no white blood cells or bacteria on smear, and the culture was negative. No deaths occurred during the hospitalization or within 30 days after the operation. Routine perioperative antibiotics were used, and most wounds were drained with closed suction drainage. Routine intraoperative cholangiography was also done. On the basis of the favorable morbidity and mortality in this large group of patients and a review of the literature, we recommend the routine use of antibiotics and cholecystectomy for most patients with gallstones.