Ultrasensitive isotope trace analyses with a magneto-optical trap

Laser manipulation of neutral atoms has been used to count individual krypton-85 and krypton-81 atoms present in a natural krypton gas sample with isotopic abundances in the range of 10(-11) and 10(-13), respectively. This method of isotope trace analysis is free of contamination from other isotopes and elements and can be applied to several different isotope tracers for a wide range of applications. The demonstrated detection efficiency is 1 x 10(-7). System improvements could increase the efficiency by many orders of magnitude.

Ectopic semaphorin-1a functions as an attractive guidance cue for developing peripheral neurons

Transmembrane and secreted glycoproteins of the semaphorin family are typically classified as inhibitory neuronal guidance molecules. However, although chemorepulsive activity has been demonstrated for several semaphorin family members, little is known about the function of the numerous transmembrane semaphorins identified to date. Here we demonstrated that the extracellular semaphorin domain of a transmembrane semaphorin, semaphorin-1a, could actively perturb axon pathfinding in vivo when presented homogenously as a recombinant freely soluble factor. When ectopic overexpression was limited to defined epithelial regions, semaphorin-1a could directly steer axons by acting as an attractive guidance molecule.

Prospective multicentre study comparing levonorgestrel implants with a combined contraceptive pill: final results

Norplant is a hormonal, long term method of contraception requiring the sub-dermal placement of six flexible capsules containing levonorgestrel in the inner aspect of the upper non-dominant arm. This open, prospective, multicentre, parallel group study, comparing the acceptability of Norplant and a combined pill, was originally designed to follow 700 subjects for five years, but was discontinued early. The main outcome criteria were duration of use and reason for discontinuation if appropriate. This final analysis, concerning the 364 subjects who used the implant and 307 subjects who used a gestodene/ethinyloestradiol combined pill, shows a statistically significantly higher (p<0.001) continuation rate amongst the implant users at 83.4 per cent compared to the pill users at 64.4 per cent at one year and this difference decreased only slightly by two years. The most common reasons for discontinuation by the end of the study were adverse events in both groups (menstrual and then mood changes in the implant group and mood changes and then headaches in the pill group). From the whole cohort the proportion which were 'very satisfied' were higher in the implant group (28.5 per cent compared to 14.6 per cent). This study confirms, in the UK, a high continuation rate for implant users similar to other countries as reported in the literature. If acceptability and continuation rates are similar in the none study setting, then a substantial number of women will seek removal of the implant and possible reinsertion five years after the time of initial high popularity (ie 1999). Doctors need to be prepared for this possible high level of activity.

Magnitude of functional adaptation after intestinal resection

Intestinal adaptation after resection has been much studied, but rarely examined in an integrative context. Hence we assessed the effects of resection and subsequent adaptation on the quantitative relationship between dietary glucose load and gut capacity to transport glucose. The ratio of capacity to load is termed the "safety factor." Our objectives were to determine 1) the time course of intestinal adaptation after resection, 2) whether adaptation is quantitatively complete, 3) whether survival requires maintaining a safety factor of at least 1.0 for glucose transport, 4) the effect of altered energy demands on adaptation, and 5) the relationship between the amount of tissue removed and the magnitude of functional adaptation. We performed 80% resection of the small intestine on Sprague-Dawley rats and measured small intestinal glucose uptake capacity, dietary glucose load, and gut gross morphology at 1, 5, and 10 wk postsurgery. Nearly all aspects of adaptation were complete by 1 wk postsurgery. After resection, remnant small intestine mass increased by over fivefold within 1 wk, to reach 50-70% of its preresection value. However, mass-specific glucose uptake activity was reduced, so that intestinal regeneration restored uptake capacity to only 33% of control values. Increased energetic demands had only modest effects on intestinal adaptation. Although the safety factor for small intestinal glucose uptake remained <1.0 (i.e., capacity < load) after adaptation to resection, nearly all rats survived. Hindgut fermentation of nonabsorbed nutrients appeared to contribute to that survival, despite inadequate small intestinal capacity. After less massive resection surgeries (25, 50, and 75% resections), the percent increase in glucose uptake capacity increased with the amount of tissue removed.

Discrete roles for secreted and transmembrane semaphorins in neuronal growth cone guidance in vivo

From the initial stages of axon outgrowth to the formation of a functioning synapse, neuronal growth cones continuously integrate and respond to multiple guidance cues. To investigate the role of semaphorins in the establishment of appropriate axon trajectories, we have characterized a novel secreted semaphorin in grasshopper, gSema 2a. Sema 2a is expressed in a gradient in the developing limb bud epithelium during Ti pioneer axon outgrowth. We demonstrate that Sema 2a acts as chemorepulsive guidance molecule critical for axon fasciculation and for determining both the initial direction and subsequent pathfinding events of the Ti axon projection. Interestingly, simultaneous perturbation of both secreted Sema 2a and transmembrane Sema I results in a broader range and increased incidence of abnormal Ti pioneer axon phenotypes, indicating that different semaphorin family members can provide functionally distinct guidance information to the same growth cone in vivo.

Filopodial adhesion does not predict growth cone steering events in vivo

Migration of growth cones is in part mediated by adhesive interactions between filopodia and the extracellular environment, transmitting forces and signals necessary for pathfinding. To elucidate the role of substrate adhesivity in growth cone pathfinding, we developed an in vivo assay for measuring filopodial-substrate adhesivity using the well-characterized Ti pioneer neuron pathway of the embryonic grasshopper limb. Using time-lapse imaging and a combination of rhodamine-phalloidin injections and DiI labeling, we demonstrate that the filopodial retraction rate after treatment with cytochalasin D or elastase reflects the degree of filopodial-substrate adhesivity. Measurements of filopodial retraction rates along regions of known differing substrate adhesivities confirmed the use of this assay to examine filopodial-substrate adhesion during in vivo pathfinding events. We analyzed 359 filopodia from 22 Ti growth cones and found that there is no difference between the retraction rates of filopodia extending toward the correct target (on-axis) and filopodia extending away from the correct target (off-axis). These results indicate on-axis and off-axis filopodia have similar substrate adherence. Interestingly, we observed a 300% increase in the extension rates of on-axis filopodia during Ti growth cone turning events. Therefore, in addition to providing filopodia with important guidance information, regional cues are capable of modulating the filopodial extension rate. The homogeneity in filopodial retraction rates, even among these turning growth cones in which differential adhesivity might be expected to be greatest, strongly establishes that differential adhesion does not govern Ti pioneer neuron migration rate or pathfinding. We propose that the presence of local differences in receptor-mediated second messenger cascades and the resulting assembly of force-generating machinery may underlie the ability of filopodial contacts to regulate growth cone steering in vivo.

Relevance of the National “Mussel Watch” Program To Seafood Fisheries Management Issues During Oil Spill Response

Concentrations of polycyclic aromatic hydrocarbons in U.S. coastal mussels and oysters sampled in 1995 and 1996 range 500-fold, from about 8 parts per billion (ppb) wet weight (ww) in mussels from a site in the Southern California to over 3,000 ppb ww in oysters from several Gulf Coast embayments; the U.S. national mean concentration for 258 sites was about 140 ppb ww or about 700 ppb dry weight (dw). Regions with the lowest background concentrations (less than 30 ppb ww) include Alaska, the open coast of California and western Louisiana. Sites with the highest background concentrations (greater than 1000 ppb ww) include many urban and rural harbors and regions such as Puget Sound. On a nationwide basis there are no longterm decreases or increases in shellfish polycyclic aromatic hydrocarbon (PAH) concentrations despite clearly decreasing concentrations for other chemical contaminants. These results are relevant for developing criteria for closing and opening fisheries during responses to oil spills.

Ontogeny of intestinal safety factors: lactase capacities and lactose loads

We measured intestinal safety factors (ratio of a physiological capacity to the load on it) for lactose digestion in developing rat pups. Specifically, we assessed the quantitative relationships between lactose load and the series capacities of lactase and the Na+-glucose cotransporter (SGLT-1). Both capacities increased significantly with age in suckling pups as a result of increasing intestinal mass and maintenance of mass-specific activities. The youngest pups examined (5 days) had surprisingly high safety factors of 8-13 for both lactase and SGLT-1, possibly because milk contains lactase substrates other than lactose; it also, however, suggests that their intestinal capacities were being prepared to meet future demands rather than just current ones. By day 10 (and also at day 15), increased lactose loads resulted in lower safety factors of 4-6, values more typical of adult intestines. The safety factor of SGLT-1 in day 30 (weanling) and day 100 (adult) rats was only approximately 1.0. This was initially unexpected, because most adult intestines maintain a modest reserve capacity beyond nutrient load values, but postweaning rats appear to use hindgut fermentation, assessed by gut morphology and hydrogen production assays, as a built-in reserve capacity. The series capacities of lactase and SGLT-1 varied in concert with each other over ontogeny and as lactose load was manipulated by experimental variation in litter size.

Glucose uptake in dilated small intestine

BACKGROUND/PURPOSE

The development of dilated small intestine in patients with short bowel syndrome results in increased mucosal surface area. This study examines whether the incremental increase in surface area leads to a proportional increase in absorptive function of the small intestine.

METHODS

Partial obstruction of the small intestine was created in rats by placing an intussusception valve in the proximal jejunum. Rats that underwent sham operations served as controls. One week postoperatively, the small intestine proximal and distal to the valve was removed. The intestinal diameter proximal and distal to the obstruction was measured. The rate of glucose uptake was measured by the everted sleeve technique. The results were analyzed by analysis of variance (ANOVA).

RESULTS

The intestine proximal to the valve was significantly dilated and thickened when compared with the intestine distal to the valve. The wet mass per centimeter of the dilated segment was 2.5 times that of the control group (P<.001). The glucose uptake capacity of the dilated segment was slightly higher than that of the control group (540 v 420 nmol/min/cm, P<.05). However, the specific glucose uptake rate was reduced significantly in the intestine proximal to the valve (247 v 335 nmol/min/cm2, P<.01).

CONCLUSIONS

Although the partial obstruction of small intestine resulted in a substantial increase in the intestinal surface area, the absorptive capacity of the dilated intestine per unit surface area was decreased significantly. This translated ultimately into a slight increase in the overall functional absorptive capacity of glucose in the small intestine. These results suggest that dilated small intestine may not enhance mucosal absorption.

Atlantoaxial subluxation after otoplasty

A case of iatrogenic atlantoaxial subluxation after bilateral otoplasty is presented. Cineradiography was required for definitive diagnosis. Bed rest and Halter traction successfully resolved the condition. Great care is required while turning the head during skin preparation, draping, planning, and surgery, especially in young children. A high index of suspicion is necessary when a child develops torticollis after otoplasty.

Is there still a role for traditional methods in the management of fractures of the zygomatic complex?

With the introduction of low-profile mini-plating systems, a trend has developed towards open reduction and rigid internal fixation (ORIF) of fractures of the cranio-facial skeleton. The current policy for management of zygomatic fractures in our unit is to attempt primary reduction by traditional methods, and proceed to ORIF in the event of unsatisfactory fracture stability or alignment. Over a one-year period, 109 patients underwent surgical correction of fractures of the zygomatic complex. Standard Gilles' elevation was performed in 71 cases, percutaneous elevation in three cases, and ORIF was performed in 35 cases. Mean follow-up was 190 days. One case of persistent infraorbital step and three cases of residual malar flattening were documented in patients who underwent Gilles or percutaneous elevation. Morbidity associated with ORIF was minimal. We conclude that while ORIF of zygomatic fractures may offer better results than traditional methods in the management of complex fractures, traditional methods still have a role to play in less complex fractures.

A study of suicide and attempted suicide by self-immolation in an Irish psychiatric population: an increasing problem

In the Western World self-immolation is an uncommon but dramatic method of attempting suicide. In-patients who attempt suicide by fire-setting tend to be female with severe psychopathology. In a previous study from the South of Ireland, seven cases from a psychiatric and prison population were identified in a five year period from 1984 to 1989. This would represent an annual rate of 1.07 per cent of burns treated in the burns unit at Cork University Hospital. In this study 12 cases were identified for the years 1994 and 1995. This represents an increase of 3.5 per cent from 1.07 to 4.6 per cent of all burns treated at the same institution. Ten of these patients had a previous psychiatric history and eight of them were resident on a psychiatric ward when they committed the act. Seven of the patients were found to have a high degree of suicide intent of whom four died of their injuries, which gives a mortality rate for this group of 33 per cent. Effective prevention policies are necessary if this increasing problem is to be curtailed.

Modulation of the discriminative stimulus and rate-altering effects of cocaine by competitive and noncompetitive N-methyl-D-aspartate antagonists

The purpose of this study was to determine the extent to which N-methyl-D-aspartic acid (NMDA) antagonists modified the discriminative stimulus effects of cocaine in rats trained to discriminate 5 mg/kg cocaine from vehicle on a fixed-ratio schedule of food presentation as well as the rate-altering effects of cocaine in rats maintained on a fixed-interval schedule of food presentation. NMDA-associated ion channel blockers (dizocilpine, phencyclidine, and magnesium chloride) and competitive NMDA antagonists (NPC 17742 and CGP 37849) displayed similar behavioral effects when administered alone: each drug engendered intermediate levels of cocaine-appropriate responses and rate-dependent effects on food-reinforced operant responding. Selected doses of dizocilpine, magnesium chloride, and phencyclidine given in combination with 1 mg/kg cocaine produced more cocaine-appropriate responses than this dose of cocaine alone. In addition, dizocilpine and magnesium chloride each attenuated the discriminative stimulus effects of higher doses of cocaine. The competitive NMDA antagonists did not appreciably modify the discriminative stimulus effects of any dose of cocaine. Under the fixed-interval schedule, each NMDA antagonist attenuated the effects of 3 mg/kg cocaine, which normally produced maximal increases in response rate. Attenuation of the rate-decreasing effects of the highest dose of cocaine (30 mg/kg) also were observed after pretreatment with dizocilpine and magnesium chloride. These findings demonstrated differences in the way that NMDA-associated ion channel blockers and competitive NMDA antagonists interact with cocaine, and suggest that some NMDA-associated ion channel blockers may either enhance or antagonize the effects of cocaine, depending on the dose and type of behavioral procedure.

Is it possible to predict limb viability in complex Gustilo IIIB and IIIC tibial fractures? A comparison of two predictive indices

The patient with severe lower limb trauma presents a management dilemma; whether to amputate primarily or to attempt limb salvage. In recent years, many predictive indices have been published which purport to identify limbs which are non-viable. We retrospectively applied two recently described indices, the Mangled Extremity Severity Score (MESS) and the Limb Salvage Index (LSI), to 54 limbs in 50 patients with either Gustilo IIIB or IIIC complex tibial fractures. There were 22 amputations (40.7 per cent) in the series. The mean MESS score in the limb salvage group was 3.8 (range 2-10), and the mean MESS score in the amputation group was 7.7 (range 4-13) (P < 0.0001). The mean LSI score in the limb salvage group was 3.6 (range 3-8), and the mean LSI score in the amputation group was 6.9 (P < 0.01). However, in the group with MESS scores > 7 (which recommends amputation), there were three limbs which were salvaged with acceptable functional outcome. Similarly, in those with LSI scores > 6 (which recommends amputation), there were seven limbs successfully salvaged. A MESS > 7 offered a greater relative risk of amputation (9.2) than a LSI score > 6 (5.3). We found both indices of use in predicting limb salvage and functional outcome. However, neither is sufficiently accurate to be considered absolutely reliable in clinical practice.

The range of excursion of flexor tendons in Zone V: a comparison of active vs passive flexion mobilisation regimes

A number of early postoperative mobilisation regimes have been developed in an attempt to increase tendon excursion and gliding and thereby reduce formation of adhesions following repair of flexor tendons. Early active flexion mobilisation regimes are becoming more popular, and have replaced early passive flexion regimes in many centres. The aim of the present study was: (a) to determine the range of excursion of flexor tendons in Zone V, and (b) to compare the excursion ranges between active (Belfast) and passive (modified Duran) flexion mobilisation regimes postoperatively. This was done (a) in two cadavers, and (b) in two patients intraoperatively, and postoperatively at 10 days, 3 weeks and 6 weeks. With passive flexion, the mean tendon excursion in Zone V in cadavers was 1 mm for flexor digitorum superficialis (FDS), flexor digitorum profundus (FDP) and flexor pollicis longus (FPL) tendons respectively. With simulated active flexion, the mean tendon excursion was 14 mm, 10 mm and 11 mm respectively. The mean tendon excursion in clinical cases intraoperatively following passive flexion was 2 mm for FDS, FDP and FPL respectively; following simulated active flexion it was 10 mm, 11 mm and 11 mm for FDS, FDP and FPL respectively. On the tenth day following repair, the mean excursions of FDS, FDP and FPL were 1 mm, 4 mm and 4 mm on passive flexion as compared to 3 mm, 10 mm and 12 mm on active flexion respectively. Three weeks postoperatively, the mean excursions of FDS, FDP and FPL tendons were 1 mm, 2 mm and 1 mm on passive flexion as compared to 5 mm, 15 mm on active flexion respectively. Six weeks postoperatively, the mean excursions of FDS, FDP and FPL tendons were 9 mm, 7 mm and 4 mm on passive flexion as compared to 12 mm, 33 mm and 20 mm on active flexion respectively. These results demonstrate an increased excursion of repaired flexor tendons in Zone V following an active flexion mobilisation regime as compared to a passive flexion mobilisation regime.

Calcium alginate dressings promote healing of split skin graft donor sites

A prospective controlled trial was carried out to assess the healing efficacy of calcium alginate and paraffin gauze on split skin graft donor sites. Thirty patients were randomised to the calcium alginate group and 21 to the paraffin gauze group. The donor sites were assessed at 10 days post harvesting to determine if they were completely healed (100%) or not. Twenty one of the 30 patients dressed with calcium alginate were completely healed at day 10, while only 7/21 in the paraffin gauze group were healed (p < 0.05). There were two infections in the study, both occurring in the alginate group while there was no difference in dressing slippage between the two groups. Calcium alginate dressings provide a significant improvement in healing split skin graft donor sites.

Transmembrane grasshopper Semaphorin I promotes axon outgrowth in vivo

Members of the Semaphorin family of glycoproteins play an important role in axonal pathfinding by functioning as inhibitory guidance cues. Here we provide evidence that a transmembrane form of Semaphorin (Semaphorin I), which is expressed by bands of epithelial cells in the developing grasshopper limb bud, functions as an attractive/permissive cue for the growth cones of the subgenual organ. In addition, we demonstrate that Semaphorin I is needed for initial axonal outgrowth from the subgenual organ. These results are consistent with an alternative function for a transmembrane form of Semaphorin and may explain the previously reported arrest of the proximal extension of the subgenual organ growth cones in the absence of the Ti1 pioneer pathway.

Activation of ribosomal protein S6 kinase in psoriatic lesions and cultured human keratinocytes by epidermal growth factor receptor ligands

p70 Ribosomal protein S6 kinase is a critical down-stream effector of a mitogen-stimulated signaling pathway that is selectively inhibited by the immunosuppressant rapamycin. The purpose of this study was to quantify S6 kinase expression in psoriatic involved, uninvolved, and normal epidermis and to characterize regulation of S6 kinase activity in cultured normal human keratinocytes. S6 kinase activity was increased 4-fold in psoriatic lesions (1.63 +/- 0.25 pmol per min per mg, n = 6), compared to nonlesional (0.44 +/- 0.12 pmol per min per mg, n = 6, p < 0.01), and normal (0.35 +/- 0.14 pmol per min per mg, n = 7, p < 0.01) epidermis. In contrast, S6 kinase mRNA and protein levels were not significantly different among psoriatic lesional, nonlesional, and normal epidermis. In keratinocytes, S6 kinase activity was stimulated 3-fold by mitogenic epidermal growth factor (EGF) receptor ligands, EGF and transforming growth factor-alpha (TGF-alpha), but not by cytokines interleukin-1alpha, tumor necrosis factor-alpha, interferon-gamma, or transforming growth factor-beta1. TGF-alpha stimulation of S6 kinase activity was inhibited in a concentration-dependent manner by rapamycin (IC50 < 0.2 nM) and the specific EGF receptor antagonist PD153035 (IC50 = 20 nM). Rapamycin also inhibited EGF-stimulated proliferation of keratinocytes (IC50 = 0.2 ng per ml) with a potency similar to that reported for inhibition of T-cell proliferation. We conclude: (i) the mitogenic signaling pathway(s) regulating S6 kinase is activated in psoriatic lesions, thus accounting for increased S6 kinase activity in the absence of increased S6 kinase gene or protein expression; (ii) S6 kinase activation in lesional keratinocytes likely occurs in response to EGF receptor stimulation by TGF-alpha and/or amphiregulin, which are known to be elevated in psoriatic lesions; and (iii) keratinocyte as well as T-cell mitogenic signaling pathways are susceptible to inhibition by rapamycin, suggesting that rapamycin may be of therapeutic benefit in the treatment of psoriasis.

Trends in the aetiology of facial fractures in the south of Ireland (1975-1993)

An aetiological review of 332 patients with facial fractures seen in a 1 year period (1993) was carried out and compared to a similar study of 266 patients, performed in this unit in 1975. Males predominated in both years. Two thirds of fractures occurred in the second and third decades. Road traffic accident (RTA) related facial fractures decreased from 27% of the total in 1975 to 17% in 1993. Assault related facial fractures increased from 18% of the total in 1975 to 27% in 1993. In both study periods nasal fractures were the most common facial fracture seen and sport was the most common cause of facial fracture. The number of patients undergoing surgery increased from 67% of the total to 79% over the same period.

Soft tissue sarcoma of the extremity

A retrospective review of 33 cases of soft tissue sarcoma of the extremity presenting over a 10 year period was undertaken. The history, patterns of referral, diagnostic investigations, procedures undertaken and outcomes were studied. We found there was a frequent delay in diagnosis and sometimes misinterpretation of biopsy specimens. Patients were seen by a variety of specialists from disciplines such as general surgery, plastic surgery, orthopaedic surgery and rheumatology. Considerable progress has been made in the treatment of soft tissue sarcomas, often allowing local control of the tumour without amputation. We believe there should be early referral of patients having these tumours to a centre where a combined multidisciplinary approach can be undertaken.

Pioneer growth cone migration in register with orthogonal epithelial domains in the grasshopper limb bud

At the onset of neural development, pioneer growth cones can migrate over epithelia or neuroepithelia along stereotyped routes that establish the pattern of initial neural tracts. These migration routes may reflect the arrangement of distinct epithelial or neuroepithelial domains. In grasshopper limb buds, a pair of afferent pioneer neurons arise in the tibia and their growth cones migrate on a stereotyped path through the limb to the CNS. In the limb buds, circumferentially-oriented epithelial domains expressing semaphorin-I, annulin, or alkaline-phosphatase, and a longitudinal domain, expressing engrailed, have been described. Using multiple-labeling techniques, we describe the relationships of these domains to each other and to the pioneer neuron pathway. Taken together, these domains establish an orthogonal pattern of regionally specific epithelial molecular markers. During much of their migration across the limb epithelium, the pioneer growth cones are in register with the axes of circumferential or longitudinal epithelial domains.

Facial fractures in Gaelic football and hurling

A one year, retrospective, epidemiological study of all facial fractures, sustained whilst playing the GAA sports of football and hurling, treated in the Cork Regional Hospital was undertaken. The results have been analysed and compared to a similar study performed in this unit in 1975. Of 332 patients treated for facial fractures, 110 (33%) were injured whilst playing sport and 47% of these occurred when playing Gaelic football or hurling (52 injuries in all). Eighty per cent of Gaelic football and hurling patients required operative treatment. All surgery was performed under general anaesthetic. The numbers of hurling fractures have more than halved since 1975-76. This coincides with an increase in the numbers hurling, an increase in the use of protective headgear and vastly improved coaching. This study demonstrates that improved safety can be achieved without diluting sporting enjoyment.

One hundred and ten sports related facial fractures

In a 1 year period (1993) 332 facial fractures were treated in Cork Regional Hospital. Of these 110 (33%) were sports related. Males accounted for 94.5% of patients and 77% of patients were aged below 30 years. Nasal fractures were the most common fractures seen (56%). Almost half (49%) of sports related facial fractures occurred while playing Gaelic games. The incidence of hurling fractures has been more than halved over the last 20 years. Seventy eight percent of patients required operative treatment.

Axonal transport of tubulin in Ti1 pioneer neurons in situ

In neurons, tubulin is synthesized only in the cell body or dendrites, yet the growing axon requires a steady supply of this protein at the growth cone. Hence, some mechanism must exist to move tubulin from the cell body to the growth cone. Transport could conceivably occur by simple diffusion, translocation of polymer, or some form of monomer or oligomer transport. Evidence for all these has been presented in a variety of experimental systems. We have directly studied the movement of microtubules in 12 growing axons in live grasshopper Ti1 neurons in their natural environment by labeling the polymer with a caged fluorophore, biscaged fluorescein. No evidence of polymer transport was found. Hence, tubulin movement in these neurons must occur by movement of monomeric tubulin, either by transport or diffusion. To resolve these conflicting views, we discuss the conditions under which diffusion is feasible as a transport mechanism.

Biliary tract complications after liver transplantation

OBJECTIVE

To assess the incidence, type, and treatment of biliary complications after orthotopic liver transplantation.

DESIGN

Case series.

SETTING

Tertiary referral center.

PATIENTS

One hundred ninety consecutive adults who underwent 220 orthotopic liver transplantations with biliary reconstruction between January 1, 1989, and December 31, 1993, with follow-up of all survivors to May 1994.

MAIN OUTCOME MEASURES

Incidence, type, and treatment of biliary complications.

RESULTS

Biliary complications were identified in 65 of the 190 patients who underwent biliary reconstruction (49 of 147 with choledochocholedochostomy and 16 of 43 with Roux-en-Y choledochojejunostomy). The group with complications who had choledochocholedochostomy had 32 biliary leaks (22 T-tube related), 11 strictures or obstructions, and six cases of choledocholithiasis. Twelve percent of choledochocholedochostomies were converted to choledochojejunostomies, while 26 of 49 biliary complications in patients who had choledochocholedochostomies were treated nonoperatively. Elective removal of T tubes resulted in biliary leak in 15 of 89 patients, treated nonoperatively in 12. Leaks (unrelated to scheduled removal of the tube) occurred earlier than strictures (choledochocholedochostomy, mean +/- SEM 25.6 +/- 5.8 vs 184.7 +/- 61.0 days; choledochojejunostomy, 13.4 +/- 4.4 vs 521.0 +/- 142.0 days) and were more often treated operatively (choledochocholedochostomy, 14 of 17 vs three of seven; choledochojejunostomy, four of five vs three of eight). Three deaths were associated with early biliary leaks, all in patients with preexisting multiorgan dysfunction. There was no significant difference in the incidence of biliary complications by type of reconstruction, year of transplantation, age, UNOS (United Network for Organ Sharing) status, preservation time, or indication for transplantation.

CONCLUSIONS

Biliary complications are common after orthotopic liver transplantation but are rarely an isolated cause of death. Stenting of the choledochocholedochostomy or choledochojejunostomy anastomosis does not prevent strictures, and T tubes are associated with a high incidence of biliary leakage on removal. Nonoperative interventions have an increasing role in the treatment of biliary complications.

Cytoskeletal events in growth cone steering

Oriented neural outgrowth is dependent upon the capability of growth cones to reorient the direction of their migration in response to contact with guidance information. Recent observations have directed attention toward the role of actin distribution and concentration in transmitting localized peripheral signals to central elements of the growth cone, particularly microtubules.

Accumulation of actin in subsets of pioneer growth cone filopodia in response to neural and epithelial guidance cues in situ

Directed outgrowth of neural processes must involve transmission of signals from the tips of filopodia to the central region of the growth cone. Here, we report on the distribution and dynamics of one possible element in this process, actin, in live growth cones which are reorienting in response to in situ guidance cues. In grasshopper embryonic limbs, pioneer growth cones respond to at least three types of guidance cues: a limb axis cue, intermediate target cells, and a circumferential band of epithelial cells. With time-lapse imaging of intracellularly injected rhodamine-phalloidin and rhodamine-actin, we monitored the distribution of actin during growth cone responses to these cues. In distal limb regions, accumulation of actin in filopodia and growth cone branches accompanies continued growth, while reduction of actin accompanies withdrawal. Where growth cones are reorienting to intermediate target cells, or along the circumferential epithelial band, actin selectively accumulates in the proximal regions of those filopodia that have contacted target cells or are extending along the band. Actin accumulations can be retrogradely transported along filopodia, and can extend into the central region of the growth cone. These results suggest that regulation and translocation of actin may be a significant element in growth cone steering.

Fasciclin I and II have distinct roles in the development of grasshopper pioneer neurons

We have used a new technique, micro-CALI (chromophore-assisted laser inactivation), to investigate the function of the neural cell adhesion molecules fasciclin I and II in the development of the grasshopper Ti1 neurons. Micro-CALI of fasciclin I results in defasciculation of the Ti1 axons similar to that achieved using large scale CALI (Jay and Keshishian, 1990). The initial point of axon separation corresponds to the site of laser irradiation, and defasciculation always continues distal to this point. Micro-CALI of fasciclin II prevents the initiation of Ti1 axon outgrowth but has no effect on fasciculation. This effect is restricted to a 3 hr interval between cytokinesis and growth cone emergence.

Battered children with duodenal avulsion and transection

Two cases of severe duodenal injury following child abuse are presented. One avulsion injury required pyloric exclusion. Both 2-year-old children survived without anastomotic complications. Survival after these injuries rests on the ability to apply multiple techniques for duodenal reconstruction, as well as the recognition of individual cases of abuse-associated malnutrition. A high index of suspicion following abuse-associated blunt abdominal trauma will prevent diagnostic delay in children with retroperitoneal duodenal injuries.

A novel sustained-release formulation of ibuprofen provides effective once-daily therapy in the treatment of rheumatoid arthritis and osteoarthritis

The efficacy and safety of a novel sustained-release formulation of ibuprofen given once-daily was compared with conventional-release ibuprofen tablets 400 mg given four times daily, in a single-blind, parallel-group study. This study was conducted at 84 general practice centres throughout the UK among patients with osteoarthritis or rheumatoid arthritis. An unequal randomisation in the ratio of 4:1 was carried out, with 463 patients who received sustained-release and 115 who received conventional-release ibuprofen providing evaluable data. In this study sustained-release ibuprofen was shown to be a more effective alternative to conventional ibuprofen therapy for the treatment of arthritic diseases in general practice, offering the convenience of once-daily dosing and the associated potential benefit of improved patient compliance.

Fasciclin IV: sequence, expression, and function during growth cone guidance in the grasshopper embryo

Monoclonal antibody 6F8 was used to characterize and clone fasciclin IV, a new axonal glycoprotein in the grasshopper, and to study its function during growth cone guidance. Fasciclin IV is dynamically expressed on a subset of axon pathways in the developing CNS and on circumferential bands of epithelial cells in developing limb buds. One of these bands corresponds to the location where the growth cones of the Ti1 pioneer neurons make a characteristic turn while extending toward the CNS. Embryos cultured in the 6F8 antibody or Fab exhibit aberrant formation of this axon pathway. cDNA sequence analysis suggests that fasciclin IV has a signal sequence; long extracellular, transmembrane, and short cytoplasmic domains; and shows no homology with any protein in the available data bases. Thus, fasciclin IV appears to be a novel integral membrane protein that functions in growth cone guidance.

Small cell undifferentiated carcinoma of the pancreas. Report of a patient with tumor marker studies

BACKGROUND

Small cell undifferentiated carcinoma of the pancreas is a rare type of pancreatic neoplasm.

METHODS

The authors report the clinical and pathologic aspects of a patient with this malignant lesion and an extensive serologic and immunohistochemical survey of potential ectopically produced hormones or tumor markers.

RESULTS

Neuron-specific enolase (NSE) emerged as a tumor marker.

CONCLUSIONS

NSE could be valuable in the diagnosis and management of other patients with this rare disease.

Small cell undifferentiated carcinoma of the pancreas. Report of a patient with tumor marker studies

BACKGROUND

Small cell undifferentiated carcinoma of the pancreas is a rare type of pancreatic neoplasm.

METHODS

The authors report the clinical and pathologic aspects of a patient with this malignant lesion and an extensive serologic and immunohistochemical survey of potential ectopically produced hormones or tumor markers.

RESULTS

Neuron-specific enolase (NSE) emerged as a tumor marker.

CONCLUSIONS

NSE could be valuable in the diagnosis and management of other patients with this rare disease.

Seroprevalence of Lyme disease in gray wolves from Minnesota and Wisconsin

To determine the seroprevalence of Lyme disease in gray wolves (Canis lupus) from various counties of Minnesota and Wisconsin (USA), 589 serum samples were collected from 528 wolves from 1972 to 1989. An indirect fluorescent antibody (IFA) test was used to detect the presence of antibodies against Borrelia burgdorferi. Titers of greater than or equal to 1:100 were considered positive. Results were confirmed by testing a few selected sera by Western blotting. Of the 589 sera tested, 15 (3%) had IFA titers of greater than or equal to 1:100. Three of the positive samples were collected from Douglas County in Wisconsin and twelve were from Minnesota counties. This study indicates that wolves are exposed to B. burgdorferi and are susceptible to Lyme disease.

Microtubule behavior during guidance of pioneer neuron growth cones in situ

The growth of an axon toward its target results from the reorganization of the cytoskeleton in response to environmental guidance cues. Recently developed imaging technology makes it possible to address the effect of such cues on the neural cytoskeleton directly. Although high resolution studies can be carried out on neurons in vitro, these circumstances do not recreate the complexity of the natural environment. We report here on the arrangement and dynamics of microtubules in live neurons pathfinding in response to natural guidance cues in situ using the embryonic grasshopper limb fillet preparation. A rich microtubule network was present within the body of the growth cone and normally extended into the distal growth cone margin. Complex microtubule loops often formed transiently within the growth cone. Branches both with and without microtubules were regularly observed. Microtubules did not extend into filopodia. During growth cone steering events in response to identified guidance cues, microtubule behaviour could be monitored. In turns towards guidepost cells, microtubules selectively invaded branches derived from filopodia that had contacted the guidepost cell. At limb segment boundaries, microtubules displayed a variety of behaviors, including selective branch invasion, and also invasion of multiple branches followed by selective retention in branches oriented in the correct direction. Microtubule invasion of multiple branches also was seen in growth cones migrating on intrasegmental epithelium. Both selective invasion and selective retention generate asymmetrical microtubule arrangements within the growth cone, and may play a key role in growth cone steering events.