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The effectiveness of regulatory non-target plant testing using crop species to predict the phytotoxicicity of herbicides to non-crop species was evaluated for eleven herbicides. These herbicides were representative of eight chemical classes and six modes of action. Data for non-crop plants from pre-emergence and post-emergence efficacy screening studies were compared with those for the most sensitive crop species defined by regulatory tests conducted to meet US EPA requirements. Testing under pre-emergence conditions for ten compounds indicated that for five of the compounds (K-815910, trifluralin, pyridyloxy A, pyridyloxy B and cyanazine), the most sensitive crop species was more sensitive than all the non-crop species evaluated. For metsulfuron-methyl, chlorimuron-ethyl, hexazinone and bromacil, only one of the non-crop species evaluated was more sensitive than the most sensitive crop species from regulatory tests. Data for the tenth compound, chloroacetamide, showed that four of 32 non-crop species tested in efficacy screens had at least one rate at which greater visual effects were observed than were observed for the most sensitive crop response in a regulatory test. The results of post-emergence exposure comparisons for five of the compounds (pyridyloxy A, cloransulam-methyl, chlorimuron-ethyl, cyanazine and hexazinone) indicated that the most sensitive crop species were more sensitive than all the non-crop species evaluated. Data for pyridyloxy B, metsulfuron-methyl and bromacil indicated that only one of the non-crop species evaluated was more sensitive than the most sensitive crop species. For trifluralin, three of the eight non-crop species were more sensitive than the most sensitive crop species. Data for K-815910 indicated that four of the fourteen non-crop species tested were marginally more sensitive than the most sensitive crop, but were within the same range of sensitivity. These results indicate that the current regulatory test batteries and methods using crop species effectively provide suitable sensitive indicator plants for the eleven diverse herbicides evaluated. This comparison indicates that crop species sensitivity to test substances is likely to be representative of non-crop herbaceous species response, regardless of chemical class, mode of action and magnitude or route of exposure.

One hundred and thirteen consecutive patients admitted with a perforated duodenal ulcer over a 5-year period (1978–82) and treated by simple closure have been followed prospectively over a median period of 43 months. Patients were divided into two categories according to their previous history of dyspepsia; group 1 (66 patients) with a chronic history of more than 3 months and group 2 (47 patients) where there was no history of dyspepsia or a history of less than 3 months duration. The follow-up periods were similar (group 1, 44 months; group 2, 43 months). The overall recurrence rate was 42per cent and to date only 14per cent of the total group of 113 patients have required a definitive operation. The incidence of ulcer recurrence was higher in group 1 than in group 2 in terms of total recurrence (group 1, 50per cent; group 2, 32per cent) and patients requiring further surgery (group 1, n = 14, 21 per cent; group 2, n = 7, 75per cent). Five of these 21 patients required an emergency procedure for haemorrhage or reperforation (group 1, n = 2; group 2, n = 3). There were no significant differences between the 5-year predictive recurrence rate or the requirement for definitive surgery between the groups. Five of the 27 patients currently on medical treatment have required maintenance treatment while the remaining patients receive active treatment for a mean of 20 per cent of the time since they developed recurrent ulceration. These results support continuation of our ‘wait and see’ policy following simple closure of perforated duodenal ulcer, even in patients with a history of chronic dyspepsia.

To determine whether information available at time of diagnosis of Crohn's disease can predict initial clinical course, I followed 239 patients prospectively from time of diagnosis to initial relapse. The patient's sex, smoking habits, contraceptive usage, disease extent, and presence of granulomas in the first histological specimen were recorded. No association was found between this demographic data and the interval between onset of symptoms and diagnosis, the severity of symptoms at presentation, or the time to relapse. The type of relapse, however, was influenced by the type of the first attack; 70% of relapses were of the same type as the initial attack. Cigarette smoking was associated with ileocolitis (p = 0.028). There was a trend for oral contraceptive users to have ileocolitis, whereas the presence of granulomas in the first histological specimen was not associated with a specific disease distribution. Patients with ileocolitis had more inflammatory attacks than those with ileitis or colitis (p = 0.001). There was also a trend for cigarette smokers and those on oral contraceptives to have more inflammatory attacks, but the presence of granulomas had no effect on the type of relapse. There is little to assist in prognosis of early disease when the diagnosis of Crohn's disease is first made, although the types of attacks tend to repeat themselves.A surgeon followed 239 people diagnosed with Crohn's disease while they were patients at Groote Schuur Hospital in Cape Town, South Africa between 1970 and 1988 until 1st relapse or for 10 years to determine whether risk factors of the disease predicts the clinical disease course. 156 (65%) had suffered from a relapse. The relapse type of about 70% of these cases was of the same type as the 1st attack. Cigarette smokers were more likely to experience ileocolitis than nonsmokers (47% vs. 32%; p=.028). Ileocolitis was linked to an increased number of inflammatory attacks (47% vs. 35% for ileitis and 14% for colitis; p=.001). Thus the researcher concluded that cigarette smoking is linked to Crohn's disease and influences the underlying disease process. A nonsignificant trend existed for combined oral contraceptive use and increased numbers of inflammatory attacks and ileocolitis. Histological granulomas did not effect the relapse pattern of the patients. The Quetelet Index indicated that females were more likely to be malnourished than males (561 vs. 645; p.0001). They presented with more severe Crohn's disease at diagnosis. Obstruction was responsible for 40% of relapses in patients with ileitis. Other than the fact that the type of attack 1st experienced by an individual tends to be the same as the relapse attack, this study did not provide physicians any additional information to help with prognosis of early diagnosis of Crohn's disease.

An altered small bowel permeability may be implicated in the pathogenesis of Crohn's disease. Intestinal permeability, using polyethylene glycol 400 (PEG 400) as the orally ingested probe, was assessed in 45 patients with Crohn's disease (ileal N = 14, ileocolonic N = 9, colonic N = 10, postresection N = 12), 20 first-degree relatives, and 31 controls. PEG 400 excretion was measured using a direct injection HPLC method, and results are expressed as percent of dose recovered in urine (median and range). No quantitative differences in the recovery of PEG-400 were found [Crohn's patients 21.9% (6.1-39.9), relatives 23.7% (4.9-39.9), controls 25.0% (4.5-39.7)]. In all groups, the composition of ingested and recovered PEG-400 was similar and no selective permeability to any molecular weight species was found. Disease site did not influence probe recovery [ileal 23.8% (7.7-30.6), ileocolonic 22.6% (14.4-33.8), colonic 27.8% (9.5-33.5)]. Resected patients had significantly lower PEG-400 recovery [18.8% (8.1-39.9)] than nonresected patients [23.5% (6.1-33.8%) P less than 0.02]. The data suggest either that altered intestinal permeability is not a factor in Crohn's disease or that PEG-400 is not a suitable probe.

During a 4-year period, the authors examined 19 patients with Crohn's disease and associated ocular inflammation. Seven patients had uveitis, eight had episcleritis, and four had anterior scleritis. Large peripheral corneal infiltrates developed in two patients with scleritis. Increased bowel activity was closely related to the presence of acute episcleritis but not to uveitis or scleritis. To determine risk factors for the development of ocular inflammation, this group of 19 patients was compared with a group of 93 patients with Crohn's disease in whom ocular inflammation was not present. There were no demographic differences between the groups. Patients with colitis or ileocolitis were more likely to suffer from ocular inflammation (23.9%, 17 of 71), than patients with small bowel involvement alone (2.8%, 1 of 36) (P = 0.013). Those with arthritis or arthralgia had a higher incidence of ocular inflammation (29.4%, 15 of 51), than patients without joint involvement (6.6%, 4 of 61) (P = 0.003). These results suggest that the risk of developing ocular inflammation in Crohn's disease may be related to the site of bowel involvement and to the presence of arthritis.

Map data can provide contextual cues that enhance ATR system performance. Maps, however, sometimes lack scene cues such as secondary trails. In these instances, trail detection requires map-independent approaches. Therefore, we have developed a feature-based trail detection algorithm. Its low-level function extracts features (edges, lines) that characterize trail geometry. A high-level function evaluates scene features, ranks them according to their trail-like attributes, and applies rules. Rules interpret complicated scenarios such as partial trail occlusion and high trail curvature. The algorithm demonstrates robust performance on both FLIR and TV imagery.

Objective: To review the outcome of a consecutive number of patients with primary sclerosing cholangitis (PSC) treated at one institution to define prognostic variables and determine the influence of surgery on outcome. Design: Case series of patients with PSC seen in Cape Town, South Africa, between 1981 and 1991. Setting: Tertiary referral center. Patients: Thirty-six patients with PSC were studied. Diagnosis was based on cholangiographic findings of multiple strictures of the bile ducts together with compatible clinical and biochemical features. Thirty-two patients were followed up prospectively for up to 9 years. Main Outcome Measures: Patient outcome was defined as good (stable or slowly progressive disease) or poor (death or liver transplantation). Results: During the follow-up period, seven patients with PSC died and two underwent liver transplantation. Actuarial survival at 5 years was 52%. An increased serum bilirubin concentration was the only variable at presentation that independently predicted a poor outcome. Cholangiography was unhelpful in predicting patient outcome. Six patients who developed obstructive jaundice associated with advanced liver disease underwent biliary drainage operations for surgically correctable strictures, but this did not seem to prevent progression of the disease. Two patients who progressed to end-stage liver disease went on to have liver transplantation and were alive with functioning grafts at 7 and 14 months, respectively. Conclusions: Symptomatic PSC is a progressive disorder with a poor prognosis. Our experience suggests that patients with advanced liver disease caused by PSC should be considered directly for liver transplantation rather than biliary bypass operations. (Arch Surg. 1994;129:723-728)

The dry matter content of honeydew produced by Myzus persicae feeding on artificial diets increased with increasing sucrose concentrations of the diet. Whereas the diet osmolalities ranged from 828 to 1800 milliosmolal, the honeydew osmolality was relatively constant (about 500 milliosmolal). This osmoregulatory capacity is achieved largely by variations in the mean molecular weight of glucose-containing honeydew oligosaccharides.

Electrophysiological measurements on internodal cells of Chara corallina Klein ex Willd., em. R.D.W. revealed that in the presence of (2-[4-(2′,4′-dichlorophenoxy)phenoxy]propionic acid) (diclofop) the membrane potential was very sensitive to the pH of the bathing medium. At pH 5.7, 100 micromolar diclofop caused a slow reduction in the electrogenic component of the membrane potential to the value of −123 ± 5 millivolts. Membrane resistance initially decreased, recovered transiently, then stabilized at approximately 65% of the control value. At pH 7.0, the potential appeared to plateau around −200 millivolts before rapidly declining to −140 ± 4 millivolts; removal of diclofop resulted in recovery of the electrogenic component. Diclofop reduced cytoplasmic ATP levels by 96.4% and 36.6% at pH 5.7 and 7.0, respectively. At pH 8.2, diclofop did not change the ATP concentration significantly, but induced a hyperpolarization of the membrane potential to near −250 millivolts, and also reduced or inhibited the dark-induced hyperpolarization; the light-induced depolarization was reduced to a lesser extent. DCMU applied in the light elicited the same response at the plasmalemma as placing cells in the dark. When K+ channels were opened and cells depolarized with 10 millimolar K+, diclofop induced a further depolarization of approximately 30 millivolts. Cells decoupled with HPO4−2 were still sensitive to diclofop. Currents associated with OH− efflux and HCO3− influx, as measured with a vibrating probe technique, became spatially destabilized and reduced in magnitude in the presence of diclofop. After 60 minutes, most of the cell surface was engaged in a low level of OH− efflux activity. The results indicate that diclofop may be a proton ionophore at pH 7.0 and 5.7. At pH 8.2, diclofop may inhibit the operation of the H+-ATPase and OH− efflux systems associated with HCO3− transport by perturbing the control processes that integrate the two, without a reduction in ATP concentration.

A multilumen balloon tube constructed to separate duodenal and jejunal perfusion segments was placed in the proximal small bowel of 6 healthy volunteers. The effect of nutrient mixture in the duodenum on net jejunal water and electrolyte flux was then determined. The duodenum was perfused with a balanced electrolyte solution before and after the nutrient perfusion. Net water flux in the perfused jejunum changed from absorption 27.0 ± 6.0 μl/min/cm, (mean ± SEM) to secretion 7.7 ± 7.3 μl/min/cm (P

The role of sclerotherapy in long-term management after oesophageal variceal bleeding was assessed by comparing repeated sclerotherapy by means of a rigid oesophagoscope in 37 patients with control medical management in 38 patients. Varices were eradicated in 21 of the 22 patients analysed (95%) in the sclerotherapy group, but recurred in 13 of the 21 patients (average 21·5 months). Varices persisted in 13 of 14 surviving controls. The sclerotherapy patients had fewer recurrent bleeds than control patients (43 versus 73); the majority occurred before variceal eradication and were mild. However, there was no difference in survival in the two groups. The commonest cause of death was liver failure (37 patients). 32 complications occurred in 24 patients during 258 injections. Repeated sclerotherapy failed to improve survival in this trial, although varices were eradicated and recurrent variceal bleeds were prevented with adequate follow-up.

Electrophysiological measurements were made on the mesophyll cells of wheat ( Triticum aestivum L. cv Waldron) and oat ( Avena sativa L. cv Garry) coleoptiles treated either with the herbicide diclofop-methyl (methyl 2-(4-(2′,4′-dichlorophenoxy)phenoxy)propanoate), or it9s primary metabolite diclofop, (2-(4-(2′,4′-dichlorophenoxy)phenoxy)-propanoic acid). Application of a 100 micromolar solution of diclofop-methyl to wheat coleoptiles had little or no effect on the membrane potential (E M ), however in oat, E M slowly depolarized to the diffusion potential (E D ). At pH 5.7, 100 micromolar diclofop rapidly abolished the electrogenic component of the membrane potential in both oat and wheat coleoptiles with half-times of 5 to 10 minutes and 15 to 20 minutes, respectively. The concentrations giving half-maximal depolarizations in wheat were 20 to 30 micromolar compared to 10 to 20 micromolar in oat. The depolarizing response was not due to a general increase in membrane permeability as judged from the E M 9s response to changes in K + , Na + , Cl − , and SO 4 2− , before and after treatment with diclofop and from its response to KCN treatment. In both plants, diclofop increased the membrane permeability to protons, making the E M strongly dependent upon the external pH in the range of pH 5.5 to pH 8.5. The effects of diclofop can best be explained by its action as a specific proton ionophore that shuttles protons across the plasmalemma. The rapidity of the cell9s response to both diclofop-methyl (15-20 minutes) and diclofop (2-5 minutes) makes the ionophoric activity a likely candidate for the earliest herbicidal event exhibited by these compounds.

The relapse rate after successful short-term therapy with sucralfate (Sc) or cimetidine (Cm) was studied in a group of 86 patients with recently healed duodenal or gastric ulcers. The patients were endoscoped on clinical relapse or, routinely, at 6 weeks, 6 months, and 1 year. Patients whose ulcers had healed with Cm relapsed earlier than did those whose ulcers had healed with Sc (p less than 0.05 at 12 weeks), but the cumulative relapse rate by the end of 1 year was of the order of 70% in both treatment groups. The mean duration of remission in patients who developed a recurrence was significantly greater in patients treated initially with Sc than in those treated initially with Cm--7.3 and 4.6 months, respectively (p less than 0.01).

Prostaglandin E was measured by radioimmunoassay in endoscopic biopsy specimens obtained from 7 normal healthy volunteers, 28 patients with a benign gastric ulcer, and 10 with a malignant gastric ulcer. Biopsy specimens were taken from the antral and body mucosa and from the ulcer edge in patients. The median value in normal antrum specimens was 5.15 (4.44–8.40) ng PGE/mg protein which was more than the body with 3.50 (1.86–9.28), p

The site of action of the postemergence graminicide, diclofop-methyl (DM), in susceptible plants is possibly the plasmalemma. Indole-acetic acid (IAA)- and fusicoccin (FC)-induced net proton excretion in Avena coleoptiles was inhibited by the free acid, diclofop. However, net proton excretion recovered within 2 h when 2,4-dichlorophenoxy acid (2,4-D) was added simultaneously with diclofop. Diclofop depolarized the membrane potential (Em) within 12 min but the Em recovered within 30 min when diclofop was removed and replaced with either IAA or 2,4-D. The inhibition of IAA-induced coleoptile growth by DM and the membrane effects of its acid, diclofop, were partially reversed by 2,4-D if it was added shortly after treatment of the tissue. These results are consistent with the reversal of DM injury in whole plants with 2,4-D.

Sixty-six patients with recently healed gastric ulcers were entered into a double-blind, placebo-controlled, six-month maintenance trial to determine whether sucralfate 2 g at night reduces the liability to recurrent ulceration. Thirty-three patients were randomly assigned to treatment with sucralfate and 33 were assigned to placebo. Endoscopy was performed at the time of entry into the study and at 24 weeks, or earlier if clinical relapse occurred during this period. Of the patients available for analysis, endoscopic recurrences were found in eight of the 29 patients (28 percent) randomly assigned to sucralfate and in 15 of the 27 patients (56 percent) assigned to placebo. Eight of the recurrences noted at 24 weeks were asymptomatic and, of these, five were in the placebo-treated group. The cumulative relapse rate at 24 weeks was significantly lower in the sucralfate-treated group (p less than 0.05), and the Cox-Mantel text showed a significant difference between the cumulative relapse curves of the two treatment groups over the 24-week period (p less than 0.05). The results indicate that a single maintenance dose of sucralfate 2 g at night reduces the relapse rate in patients with recently healed gastric ulceration.

Experience with 30 patients with immunoproliferative small intestinal disease followed prospectively between 1971 and 1986 is described. All presented with malabsorption or growth retardation and had similar clinical, biochemical, and radiological features, irrespective of the presence of lymphoma or immunological abnormality. Alpha-chain disease protein was detected in 4 of the 11 patients who had a non-lymphomatous, predominantly plasmacytic infiltration of the small bowel; and in 5 of the 19 cases with diffuse intestinal lymphoma. The importance of exploratory laparotomy to include full-thickness intestinal biopsy in patients who have a benign infiltrate on peroral biopsy is demonstrated by the finding of lymphoma in operative specimens in 9 of 15 patients with mature, lymphoplasmacytic cells, and 5 of 8 patients with atypical, lymphoplasmacytic cells. The majority of patients with fully established benign disease, even those elaborating alpha-chain disease protein, appeared to have a good prognosis. No patient with immunoproliferative small intestinal disease developed immunologically demonstrated alpha-chain disease or frank lymphoma, when this was not found initially at explorative laparotomy.

The conventional dosage schedule for sucralfate is 1 g 4 i.d., but a dose of 2 g 2 i.d. may be equally effective in duodenal ulcer healing. We compared the efficacy of these two regimens in duodenal ulcer healing. Seventy-seven patients with endoscopically proven duodenal ulceration were entered into a double-blind, controlled study and randomized to treatment with sucralfate 2 g 2 i.d. (on waking and at bedtime) or 1 g 4 i.d. (1/2 h before meals and at bedtime). The patients were endoscoped before entry into the study, after 4 weeks, and after 8 weeks if unhealed at 4 weeks. Of the patients considered suitable for analysis at 4 weeks, 79% (26/33) of those taking 2 g 2 i.d. had healed ulcers in comparison to 72% (23/32) of those taking 1 g 4 i.d. After 8 weeks, cumulative healing rates were 85% (28/33) and 80% (24/30), respectively. The results suggest that the more convenient dosage schedule of 2 g 2 i.d. is as effective as the 1 g 4 i.d. regimen in the short-term treatment of duodenal ulcer.

Students of eighteenth-century philosophy are familiar with the fact that Thomas Reid's criticism of the philosophy of his contemporary David Hume rested on the claim that the latter had adopted as an unquestioned presupposition a false theory of ideas deriving from the philosophy of Descartes. This is a charge which Hume never answered directly in print. Until now twentieth-century scholars have only had available a polite but uninformative letter from Hume to Reid that, basically, compliments him on the style of the manuscript of his Inquiry into the Human Mind-the work in which the criticism was first made.1 However, the recent discovery by Paul Wood of a letter from Hume to Hugh Blair, who had sent him Reid's manuscript, indicates that Hume had read Reid's work with some care.2 Moreover, Wood has now identified a manuscript, published by David Norton some ten years ago under the title 'Reid's Abstract of the Inquiry into the Human Mind', as Reid's direct answer to Hume.3 The letter contains a rather surprising criticism of Reid's own philosophynamely, that it itself rests on the theory of 'innate Ideas'

A philosopher once wrote the following words:If I examine the PTOLOMAIC and COPERNICAN systems, I endeavour only, by my enquiries, to know the real situation of the planets; that is, in other words, I endeavour to give them, in my conception, the same relations, that they bear towards each other in the heavens. To this operation of the mind, therefore, there seems to be always a real, though often an unknown standard, in the nature of things; nor is truth or falsehood variable by the various apprehensions of mankind. Though all human race should for ever conclude, that the sun moves, and the earth remains at rest, the sun stirs not an inch from his place for all these reasonings; and such conclusions are eternally false and erroneous.

The transformability of trihalomethanes, carbon tetrachloride, 1,1,1-trichloroethane, 1,2-dibromoethane, tetrachloroethylene, hexachloroethane, and dibromochloropropane was studied under conditions of denitrification, sulfate respiration, and methanogenesis. These compounds at concentrations commonly found in groundwater were continuously administered to anoxic biofilm columns that resembled groundwater environments. Acetate was the primary substrate to support microbial growth. All of the compounds studied were transformed under methanogenesis. Bromoform, bromodichloromethane, carbon tetrachloride, and hexachloroethane were transformed even under the less reducing conditions of denitrification. Some of the compounds were partially mineralized to CO 2 . However, reductive dehalogenation appeared to be the predominant mechanism for removal. Characterization of the available electron acceptors in the subsurface is important for assessing organic micropollutant biotransformation. Reaction rates observed in the laboratory biofilms indicate that biotransformation could be responsible for significant removals of these halogenated compounds in the subsurface.

Data from the Anger Camera were obtained by means of a data acquisition computer or high resolution film reader and stored on magnetic tape. Correction for nonuniformity was obtained for camera flood and stored for processing incoming data. In addition, a method of contrast enhancement which allows the user to visualize the resulting image and its histogram is described.

Two patients with inflammatory bowel disease who developed acute pancreatitis within 21 days of commencing treatment with 6-mercaptopurine are presented. Both were inadvertently reexposed to the drug and developed recurrent pancreatitis within 3 hr of a single dose.

Turgor pressure in individual sieve tubes was measured directly by gluing capillary micromanometers over exuding aphid stylets with cyanoac-rylate adhesive. Pressures of up to 10 bars were measured in sieve tubes of Salix babylonica, with an estimated accuracy of +/- 0.3 bars or better.For comparison with the direct measurements of sieve tube turgor, calculated values of turgor pressure were also obtained from the difference between leaf water potential and phloem exudate solute potential, estimated from its refractive index and sucrose content. In most cases the measured turgor pressure was greater than the calculated value. The discrepancy between the two values was most likely due to the presence of appreciable concentrations of potassium and amino acids in the phloem exudate.

Severed aphid stylets were used to follow the kinetics of sieve tube turgor and osmotic pressure (pi) responses following step changes in water potential applied to the cambial surface of willow (Salix exigua Nutt.) bark strips. The kinetics of the turgor response were monitored with a pressure transducer. In separate experiments, the kinetics of the pi response were followed by freezing point determinations on stylet exudate. The sieve tube volumetric elastic modulus in the bark strips was about 21 bars, but may be higher in intact stems. The membrane hydraulic conductivity was about 5 x 10(-3) centimeters per second per bar; several factors make it difficult to estimate its value accurately. Differences in the turgor pressure (P) and pi responses, as well as the relatively more rapid initial turgor response to a water potential (psi) change, suggested a time-dependent component in sieve tube wall elasticity.Our observations were generally not supportive of the idea that sieve tubes might osmoregulate. However, the bark strip system may not be suitable for addressing that question.Separate measurements of psi, P, and pi demonstrate that the relationship predicted by the fundamental cell water potential equation, psi = P - pi, is applicable within experimental error (+/- 0.4 bar) to sieve tube water relations.

In a five-year study of massive upper gastrointestinal hemorrhage, 143 patients had esophageal varices diagnosed on emergency endoscopic examination. Seventy-one patients had active bleeding from varices and required Sengstaken tube tamponade during at least one hospital admission. The remaining patients included 33 with variceal bleeding which had stopped and 39 who were bleeding from another source. Sixty-six of the former group of 71 patients were referred for emergency injection sclerotherapy. These 66 patients were followed prospectively to August 1980, and had 137 episodes of endoscopically proven variceal bleeding requiring Sengstaken tube control followed by injection sclerotherapy during 93 separate hospital admissions. Definitive control of hemorrhage was achieved in 95% the patients admitted to the hospital (single injection 70%; two or three injections 22%). The death rate per hospital admission was 28%. No patient died of continued variceal bleeding, and exsanguinating variceal hemorrhage no longer poses a major problem at our hospital. The combined use of initial Sengstaken tube tamponade followed by injection sclerotherapy has simplified emergency treatment in the group of patients who continue to bleed actively from esophageal varices, despite initial conservative treatment.

A procedure is described for the measurement of the sieve tube membrane potential in the phloem of bark strips from Salix exigua Nutt. Measurements were made by inserting a measuring microelectrode into sap exuding from severed stylets of the willow aphid, Tuberolachnus salignus. Data taken from 20 bark strips gave an average potential of -155 +/- 9 millivolts. Evidence is presented for an electrogenic component of the sieve tube membrane potential. The occurrence of a saturable sucrose-induced membrane depolarization is consistent with the concept of sugar accumulation by a sucrose/H(+) co-transport mechanism.

Vitamin A therapy has been claimed in isolated reports to be of benefit to patients with Crohn's disease. To investigate this further, 86 patients were entered into a long-term double-blind study of vitamin A, 50,000 U twice daily, as compared with placebo. After a mean of 14.1 mo of treatment there was no significant difference between the groups as measured by a variety of activity indices (including the National Cooperative Crohn's Disease Activity Index), the number of acute attacks, and the surgical rate. No toxic effects of vitamin A were observed during the study. In this study vitamin A has not been shown to be of benefit to patients with Crohn's disease who are in remission.