Doubling the estimate of invertebrate biomass in a rainforest canopy.

Forest canopies represent the functional interface between 90% of the Earth's terrestrial biomass and the atmosphere and include some of the most threatened of all terrestrial ecosystems. However, we lack even a basic understanding of how the biomass of plants and animals is distributed throughout forest canopies, even though this information is vital for estimating energy flow, carbon cycling, resource use and the transfer of materials within this ecosystem. Here we measure the biomass of invertebrates living in a common rainforest epiphyte, describe a striking relationship between fern size and the biomass of animals within the ferns, and reveal that one large epiphyte may contain an invertebrate biomass similar to that found in the whole of the rest of the tree crown on which it is growing. Using these data, we show that including the fauna of these epiphytes--a neglected component in rainforest ecosystems--can more than double our estimate of the total invertebrate biomass in an entire rainforest canopy.

Sex attractant of the pink bollworm moth: isolation, identification, and synthesis.

The sex attractant produced in extremely small amount by the virgin female pink bollworm moth has been isolated in pure form and identified as 10-propyl-trans- 5, 9-tridecadienyl acetate. Successful synthesis of this molecule confirms the structure and makes possible its practical use to help control this destructive pest of cotton. The attractant, for which the common name "propylure" is suggested, may be the first naturally occurring compound with propyl branching to be reported.

Intraperitoneal modification of the Rives-Stoppa repair for large incisional hernias.

INTRODUCTION: Recurrence rates for open repair of ventral/incisonal hernias historically range from 6% for the classic Rives-Stoppa repair to 35-45% for some of the techniques more commonly used in the United States. We report a modification to the classic Rives-Stoppa repair that allows intraperitoneal placement of the prosthetic, secured with a running suture. The abdominal muscles are closed over the mesh to protect it from any superficial wound problems that might develop and to restore normal architecture of the abdominal wall. METHOD: A chart review was undertaken on all patients undergoing open ventral incisional hernia repair by a single surgeon from 2000 to 2006. All hernias were repaired with the intraperitoneal modification mimicking the principles of the Rives-Stoppa repair. Patient characteristics and operative and postoperative data were collected. Primary outcome was recurrence of hernia. Secondary outcomes were complications and rate of mesh infection. RESULTS: One hundred and fifteen patients were evaluated. Thirty-four patients had repair of recurrent ventral hernias. The average patient was obese, female, and 59 years old. Twenty-five patients used tobacco, eleven were diabetic, and seven used chronic corticosteroids. Meshes utilized included ePTFE, coated polyester, coated polypropylene, and biologic mesh. Average size of mesh was 465.4 cm2. There were four recurrences (3.4%), three of which were due to mesh infection requiring mesh removal. Recurrence rate not secondary to mesh removal was 0.9%. Complications occurred in 26% with seroma formation being the most frequent (16%). CONCLUSION: The intraperitoneal modification to the original Rives-Stoppa repair leads to a very low recurrence rate for large ventral hernia repairs with minimal complications and low rate of mesh infection.

Ventralex mesh in umbilical/epigastric hernia repairs: clinical outcomes and complications.

BACKGROUND: Umbilical and epigastric hernias have historically been repaired without mesh resulting in recurrence rates in some series of up to 40%. Recent data suggests mesh repair of these hernias may decrease recurrent hernia rates. Ideal placement of the mesh is behind the defect, which is difficult to do without a large incision in these hernias unless done laparoscopically. The Ventralex hernia patch is a composite PTFE/polypropylene patch allowing intraperitoneal placement behind the hernia defect through a small incision, and without the cost of laparoscopy. To date, only one study exists evaluating this new prosthesis. METHODS: This study is a retrospective chart review of all umbilical and epigastric hernias repaired with the Ventralex hernia patch by a single surgeon. Patient characteristics and operative and post-operative data were collected. Hernia recurrence is the primary outcome. Secondary outcomes include complication rates. RESULTS: Eighty-eight patients from 2003-2006 were evaluated. The population included patients aged 25-86 (mean 52) with nineteen females (22%). The average BMI was 32 (range 18-68). Eighteen patients were smokers, five patients were diabetic, and two patients were chronic steroid users. The size of patches used were small (72%), medium (27%), and unknown (1%). Average operating room time was 52 min (range 19-194). The different types of hernias repaired were umbilical (68%), epigastric (30%), and incisional (2%). Follow-up visits ranged from 8 days to 3.1 years in all but five patients (6%). No hernia recurrences were found in follow-up. Complications included two patients (2.2%) with mesh infection requiring removal of the patch, one patient with post-operative urinary retention, and seroma formation in another patient. CONCLUSIONS: The composite PTFE/polypropylene hernia patch is effective in preventing hernia recurrence in umbilical, epigastric, and small ventral hernia repairs and can be accomplished with a low rate of complications.

Radiologic gastrostomy.

Radiologic gastrostomy has a higher success rate and a lower complication rate and offers a greater choice of tubes than percutaneous endoscopic gastrostomy (PEG). The position and configuration of the stomach and colon are clearly seen under fluoroscopy, and ultrasound can be used to locate the liver. Radiologic gastrostomy procedures can be performed when there are oropharyngeal tumors, or esophageal strictures and stents, and can be performed under local anesthesia alone. Peroral push-gastrostomies are preferable for palliative care and for patients with neurogenic dysphagia, but percutaneously inserted tubes should be used in patients with upper gastrointestinal cancers in order to avoid tumor seeding. Unfortunately, awareness of and access to radiologic techniques are still limited and this has led to the development of "adventurous" techniques for placing endoscopes in stomachs rather than applying simple fluoroscopic alternatives.

Muscle thickness, measured with ultrasound, may be an indicator of lean tissue wasting in multiple organ failure in the presence of edema.

Multiple organ failure (MOF) is accompanied by muscle wasting, but changes in body composition are frequently obscured by fluid retention (edema), mainly in superficial and visceral tissue. There is a need to assess body composition and changes in body composition in these circumstances independently of edema. A relation was sought between fat-free (lean tissue) mass [calculated from body weight and skinfold thicknesses and measured by using dual-energy X-ray absorptiometry (DXA)] and muscle thickness (measured using ultrasound at a variety of sites accessible in an unconscious supine subject) to determine which sites correlated best with lean body mass. The three best sites were midbiceps, midforearm anteriorly, and midthigh anteriorly: R2 for the simple sum of the three sites correlated with fat-free mass from skinfold thicknesses was 71.1%, and with lean tissue mass from DXA was 76.1%. Serial measurements of both muscle thickness and midupper-arm circumference in nine patients with MOF showed a complete dissociation; in all nine there was a significant negative correlation of muscle thickness with time (P < 0.05) but changes in arm circumference were random. Only one patient showed a significant negative correlation with time, seven showed no change, and one other showed a significant increase. The muscle thicknesses that correlate best with lean body mass are measured over the biceps, anterior forearm, and anterior thigh. Monitoring muscle thicknesses at these three sites identifies wasting in edematous patients as it is happening.

Radiation sensitivity of cultured rabbit aortic endothelial cells.

The radiation response of cultured rabbit aortic endothelial cells was measured using colony formation to determine survival. The dose survival curve was qualitatively similar to those reported for other cell types. At doses of 400 rad and greater, the curve was an exponential function of dose with a D0 of 120 rad and an n of 7. Exponentially growing endothelial cell cultures recovered from sublethal damage between two doses of radiation. Plateau phase cultures recovered from potentially lethal damage when incubated for 6 hr between irradiation and assay.

Perfluorochemicals and hyperbaric oxygen in radiation therapy.

It has been postulated that tumors contain hypoxic cells of decreased radiation sensitivity, which limit curability with radiation therapy. Hyperbaric oxygen has been used in an attempt to improve tumor oxygenation. The nature of the oxygen concentration-radiation sensitivity relationship (oxygen increases the slope of the radiation cell survival curve) suggests that a small number of hypoxic cells, as few as one in one million, would limit tumor curability. Oxygen moves by diffusion from the capillary into the tumor. An increase in partial pressure in the capillary will increase the effective diffusion distance. To improve tissue oxygenation effectively the partial pressure of oxygen in blood must be significantly increased throughout the length of the capillary, in particular at the venous end. Theoretical considerations indicate that hyperbaric oxygen as presently used in radiation therapy, 3 ATA, would lead to only marginal improvement. PartO2 may be as much as 0.8 atm below that of the inspired gas; this plus the consumption of oxygen along the length of the capillary lead to predictions of values for PEnd CapO2 of less than twice normal. Such considerations explain the rather limited success of hyperbaric oxygen with radiation therapy. Thus it is unnecessary to postulate an absence of hypoxic cells to explain this clinical observation. In the presence of perfluorocarbon micelles the non-hemoglobin-bound oxygen carrying capacity of blood is significantly increased. Theoretical considerations predict that the difference between PartO2 and PO2 of the inspired gas should be decreased. Furthermore, the nonhemoglobin-bound oxygen carrying capacity should be adequate to satisfy tissue consumption requirements without unloading hemoglobin, thereby avoiding the "PO2 buffering effect of hemoglobin" and permitting a significant increase in PO2 throughout the capillary length. This effect has been demonstrated using a rodent tumor model.

Enhancement of tumor radiation response by the combination of a perfluorochemical emulsion and hyperbaric oxygen.

The presence of radioresistant hypoxic cells in tumors is believed to be one of the limiting factors in achieving local tumor control by radiotherapy. Treatment with hyperbaric oxygen during irradiation has been shown to improve the radiation response of many solid tumors in rodents and of some tumors in patients. Intravenous administration of perfluorochemical emulsions combined with oxygen breathing at atmospheric pressure has also been shown to improve the radiation response of several rodent tumors. Theoretical considerations suggest that the combination of a perfluorochemical emulsion and hyperbaric oxygen should be significantly more effective than either agent alone. This hypothesis was tested by examining the radiation response of BA1112 rhabdomyosarcomas growing in WAG/rij-Y rats. Treatment with a perfluorochemical emulsion, Fluosol-DA, plus hyperbaric oxygen (3 Atmospheres O2) significantly increased the radiation response of the malignant cells in these solid tumors. The observed changes in the tumor cell survival curve suggest that the combination of Fluosol-DA and HBO decreases the proportion of severely hypoxic cells in the tumor to less than 1.5% of the original value. The effect of the Fluosol-DA dose and the duration of pretreatment with HBO are described.

Development of an 241Am applicator for continuous low-dose-rate irradiation of the rat sarcoma BA1112.

An 241Am applicator for continuous low-dose-rate irradiation of the rat sarcoma BA1112 has been developed. The irradiator consists of two disc sources, each containing 800 mCi of 241Am, an isotope which emits primarily 60 keV photons. The disc sources are held in a specially-designed light-weight helmet which surrounds the tumor on the head of the rat. Dose distributions produced by these sources have been measured using an ionization chamber, thermoluminescent dosimeters and Fricke dosimeter. A computerized treatment planning system has been modified to compute dose distributions from 241Am sources, to optimize the design of this applicator. Computed and measured dose distributions for several values of separation between the 241Am discs are presented. A survival curve for cells from tumors irradiated in vivo with this applicator has been determined by an in vitro colony formation technique. The mean lethal dose DO was found to be 720 cGy for an average tumor dose rate of 95 +/- 7 cGy/hr. The major advantages of the 241Am applicator in comparison with the 192Ir applicator used previously for continuous low-dose-rate studies are: a considerably smaller half value layer thickness and the longer half life of the radionuclide. These features make it more suitable for long-term tumor cure studies because of the lower whole body dose to the animal, the availability of relatively constant dose-rate irradiators for many years, the decreased shielding requirements for the animal care facility and the diminished exposure to laboratory personnel involved with the implants on the animals.

Combination of radiation therapy and intracranial bleomycin in the 9L rat brain tumor model.

The rat 9L brain tumor model was used to investigate the therapeutic potential of a combined modality approach using intracranial Bleomycin and radiation therapy. Bolus Bleomycin was delivered intracranially into the tumor volume via cannula guides; for continuous infusions, osmotic mini-pumps were implanted subcutaneously between the scapulae with flexible tubing to deliver the drug directly into the tumor and brain. Two to six bolus injections of Bleomycin (1 unit/kg each) over 5-11 days produced modest (usually statistically significant, p less than 0.05) increases in the median survival time compared to controls. Continuous infusion of Bleomycin by osmotic pump (10 units/kg over 7 days or 15 units/kg over 14 days) was also effective at significantly increasing median survival times compared to that of controls. Radiation therapy schedules of 10 daily fractions in 12 days (2 weeks) or 10 twice-daily fractions in 5 days produced dose-dependent increases in median survival time. Multiple bolus injections of Bleomycin when combined with fractionated radiation therapy significantly increased the median survival time due to fractionated radiation therapy alone for low doses (40 or 50 Gy). However, at higher radiation doses, the addition of Bleomycin either had no effect on median survival time or actually shortened it. Continuous infusion of Bleomycin by osmotic pump was effective when added to low dose radiation therapy in several experiments, twice for a total radiation dose of 50 Gy and once for radiation therapy of 60 Gy. However, it was also observed (once for 60 Gy and twice for 70 Gy) that the addition of continuous infusion Bleomycin either had no effect or served to decrease the improvement of median survival time obtained by radiation therapy alone. Thus, we conclude that increases in normal tissue toxicity can prevent full attainment of improved therapeutic advantage from the addition of Bleomycin to fractionated radiation therapy in the rat 9L model. These results should be considered when attempts are made to combine radiation therapy and intracranial Bleomycin for the treatment of patients with primary malignant brain tumors.

Effectiveness and biological effects of techniques used to induce hypoxia in solid tumors.

Acute hypoxia is often induced in rodent tumors during studies of the oxygenation or the therapeutic responses of the tumors, either by clamping the blood supply to the tumors or by asphyxiating the hosts with nitrogen. Analyses of data from such experiments generally assume that these processes have no effects other than the induction of hypoxia and that uniform, severe hypoxia is produced throughout the tumors. The studies described in this report test several aspects of these assumptions using BA1112 rat rhabdomyosarcomas and EMT6 mouse mammary tumors. Both clamping and asphyxiation appear to be effective in producing hypoxia in the tumors. Induction of artificial hypoxia for the times necessary for irradiation was not toxic to the tumor cells and generally did not alter the growth of unirradiated tumors. However, the techniques are not without significant effects. Prolonged clamping produced extensive cytotoxicity. Clamping BA1112 tumors for 30 min and removing the clamp just before irradiation altered the tumor cell survival curve and the TCD50. Furthermore, anesthesia and/or restraint (necessary during clamping) have significant effects on tumors and hosts. The data show that the assumptions underlying the use of clamping and N2-asphyxiation to produce hypoxia for short periods in vivo are generally reasonable for BA1112 and EMT6 tumors, but illustrate the necessity for carefully examining the effects and efficacies of the procedures in each tumor/host system.

Tumor-to-tumor variability in the hypoxic fractions of experimental rodent tumors.

Paired determinations of the radiation responses of normally-aerated and artificially hypoxic rodent tumors, performed to measure the hypoxic fractions of the tumors, were obtained from our own laboratories and from the literature. The data were reanalyzed to assess whether the variabilities in the radiation responses of the normally-aerated and artificially hypoxic tumors were similar. If there were large differences in the hypoxic fractions of individual tumors within the experiments, the variability in the data from aerobic tumors would be expected to be greater than the variability in the data from artificially hypoxic tumors (which should all be brought to uniform hypoxia and therefore uniform radioresistance). The analyses revealed the variability to be as great or greater for hypoxic tumors as for normally-aerated tumors. This finding suggests that factors other than tumor-to-tumor differences in oxygenation produce most of the variability in the radiation responses of individual tumors from an experimental tumor line.

Perforating (through-and-through) injuries of the globe. Surgical results with vitrectomy.

Fifty-one eyes of 48 patients with perforating (through-and-through) injuries of the globe were treated with vitrectomy during a 12-year period. Functional success was obtained in 32 eyes (63%), anatomic success was obtained in nine eyes (17%), and treatment failed in 10 eyes (20%). In 16 eyes (32%), 20/20 to 20/100 visual acuity was obtained; in 17 eyes (33%), 20/200 to 5/200 visual acuity was obtained; and in 18 eyes (35%), less than 5/200 visual acuity was obtained. The mechanism of injury was an important prognostic indicator of final visual outcome. Eight (62%) of 13 eyes that sustained knife or nail injuries achieved a final visual acuity of 20/50 or better, while only six (16%) of 38 eyes [corrected] with missile injuries achieved a similar level of acuity. Final visual outcome correlated well with the state of the macula and was not predicted by preoperative visual acuity. Despite improvement in surgical techniques and instrumentation, no trend toward improved visual outcomes was identified during the 12-year period.

Vitreous cefazolin levels after intravenous injection. Effects of inflammation, repeated antibiotic doses, and surgery.

We devised a standardized rabbit model of intraocular inflammation using heat-killed Staphylococcus epidermidis as the inducing organism. We applied this model to study the effects of (1) inflammation, (2) repeated antibiotic doses, and (3) surgical status of the eye on cefazolin levels in the vitreous cavity after intravenous administration. Intravenous cefazolin sodium, 50 mg/kg, was administered every 8 hours for 48 hours. Eyes were harvested for assay of vitreous cavity antibiotic levels at various intervals from 1 to 49 hours. Drug levels were compared in inflamed and noninflamed eyes under both phakic and aphakic/vitrectomized conditions. At 1 hour, levels in phakic specimens were 3.0 mg/L in inflamed eyes vs undetectable in noninflamed eyes (P less than .01), but progressively increased to 10.6 mg/L at 49 hours (P less than .02) in inflamed eyes only. Levels in aphakic/vitrectomized eyes at 1 hour were 6.7 mg/L in inflamed eyes vs 4.2 mg/L in noninflamed eyes (P less than .1), but progressively increased to 24.9 mg/L at 49 hours (P less than .001) in inflamed eyes only. Levels at 49 hours in inflamed phakic and inflamed aphakic/vitrectomized eyes were well above the minimum inhibitory concentrations for organisms termed sensitive to cefazolin. We would conclude, therefore, that repeated doses of intravenous cefazolin may play an important adjunctive role in the treatment of endophthalmitis.

Evaluation of a delivery system providing long-term release of cyclosporine.

OBJECTIVES: To examine the clearance of cyclosporine after intravitreal injection and to assess the kinetics and toxic effects of an intravitreal device that provides sustained delivery of cyclosporine. METHODS: Rabbits were divided into two groups to evaluate (1) the elimination kinetics after 1-microgram and 10-microgram intravitreal injections of cyclosporine and (2) the levels produced after implantation of a device that contained cyclosporine over 6 months. The toxic effects of the intravitreal device over 6 months were assessed in rabbits and cynomolgus monkeys. RESULTS: After the 10-microgram injection, the half-life was longer (10.8 hours vs. 4.2 hours) and the distribution volume was smaller (1.7 mL vs 3.2 mL) than after the 1-microgram injection. This difference can be attributed to saturable partitioning of the drug. The device resulted in a vitreous concentration of approximately 500 ng/mL throughout the study period. In the rabbit it resulted in reversible lens opacification and decreased b-wave amplitude. This toxic effect was not detected in the monkey. CONCLUSIONS: The device produces sustained intravitreal levels of cyclosporine. Although it was associated with reversible toxic effects in the rabbit, it was well tolerated in primates. Sustained-release implants are a promising new treatment for chronic uveitis.

Treatment of cytomegalovirus retinitis with an intraocular sustained-release ganciclovir implant. A randomized controlled clinical trial.

BACKGROUND AND METHODS: We performed a randomized controlled clinical trial to assess the safety and efficacy of a 1 microgram/h ganciclovir implant for the treatment of newly diagnosed cytomegalovirus (CMV) retinitis in patients with the acquired immunodeficiency syndrome (AIDS). Patients with previously untreated peripheral CMV retinitis were randomly assigned either to immediate treatment with the ganciclovir implant or to deferred treatment. Standardized fundus photographs were taken at 2-week intervals and analyzed in a masked fashion. The study end point was progression of retinitis based on the photographic assessment. RESULTS: Twenty-six patients (30 eyes) were enrolled. The median time to progression of retinitis was 15 days in the deferred treatment group (n = 16) vs 226 days in the immediate treatment group (n = 14) (P < .00001, log-rank test). During the study, 39 primary implants and 12 exchange implants were placed in immediate-treatment eyes, deferred-treatment eyes that progressed, or contralateral eyes that developed CMV retinitis. Postoperative complications in the total series included seven late retinal detachments and one retinal tear without detachment. Final visual acuity was 20/25 or better in 34 of 39 eyes. The estimated risk of developing CMV retinitis in the fellow eye was 50% at 6 months. Biopsy-proven visceral CMV disease developed in eight (31%) of 26 patients. The median survival was 295 days. CONCLUSION: The ganciclovir implant is effective for the treatment of CMV retinitis. Patients with unilateral CMV retinitis treated with the implant are likely to develop CMV retinitis in the fellow eye, and some patients will develop visceral CMV disease.

Ganciclovir implant exchange. Timing, surgical procedure, and complications.

BACKGROUND: The ganciclovir implant is effective for the treatment of cytomegalovirus (CMV) retinitis. The device eventually runs out of drug, however, and must be replaced. We report our experience with exchanging ganciclovir implants during the course of a randomized clinical trial. METHODS: During our study, patients with newly diagnosed peripheral CMV retinitis were treated with a ganciclovir implant. The implant was scheduled for exchange at 32 weeks. It was exchanged earlier if progression of CMV retinitis occurred. Patient examinations and standard fundus photography were performed at 2-week intervals after the exchange procedure. RESULTS: Twenty-six exchange procedures were performed. Twenty-two eyes in 15 patients received a second implant and 4 eyes in 4 patients later received a third implant. Cytomegalovirus retinitis was rendered or maintained inactive in 22 of 23 cases with more than 1 month of follow-up after the second or third implants. Complications after the second implant procedure included transient vitreous hemorrhage in 5 eyes, postoperative inflammation in 1 eye, and retinal detachment in 1 eye. Median visual acuity returned to 20/25 by 28 days and to 20/20 by 42 days. Complications after the third implant procedure included dense vitreous hemorrhage in 3 of 4 eyes. Median survival time after a second implant procedure was 89 days. CONCLUSIONS: The initial ganciclovir implant exchange procedure is well tolerated with continued long-term control of CMV retinitis. Multiple reentries through the same wound may be associated with an increased risk for vitreous hemorrhage.