TMEM106B coding variant is protective and deletion detrimental in a mouse model of tauopathy

TMEM106B is a risk modifier of multiple neurological conditions, where a single coding variant and multiple non-coding SNPs influence the balance between susceptibility and resilience. Two key questions that emerge from past work are whether the lone T185S coding variant contributes to protection, and if the presence of TMEM106B is helpful or harmful in the context of disease. Here, we address both questions while expanding the scope of TMEM106B study from TDP-43 to models of tauopathy. We generated knockout mice with constitutive deletion of TMEM106B, alongside knock-in mice encoding the T186S knock-in mutation (equivalent to the human T185S variant), and crossed both with a P301S transgenic tau model to study how these manipulations impacted disease phenotypes. We found that TMEM106B deletion accelerated cognitive decline, hind limb paralysis, tau pathology, and neurodegeneration. TMEM106B deletion also increased transcriptional correlation with human AD and the functional pathways enriched in KO:tau mice aligned with those of AD. In contrast, the coding variant protected against tau-associated cognitive decline, synaptic impairment, neurodegeneration, and paralysis without affecting tau pathology. Our findings reveal that TMEM106B is a critical safeguard against tau aggregation, and that loss of this protein has a profound effect on sequelae of tauopathy. Our study further demonstrates that the coding variant is functionally relevant and contributes to neuroprotection downstream of tau pathology to preserve cognitive function.

TMEM106B coding variant is protective and deletion detrimental in a mouse model of tauopathy

TMEM106B is a risk modifier for a growing list of age-associated dementias including Alzheimer’s and frontotemporal dementia, yet its function remains elusive. Two key questions that emerge from past work are whether the conservative T185S coding variant found in the minor haplotype contributes to protection, and whether the presence of TMEM106B is helpful or harmful in the context of disease. Here we address both issues while extending the testbed for study of TMEM106B from models of TDP to tauopathy. We show that TMEM106B deletion accelerates cognitive decline, hindlimb paralysis, neuropathology, and neurodegeneration. TMEM106B deletion also increases transcriptional overlap with human AD, making it a better model of disease than tau alone. In contrast, the coding variant protects against tau-associated cognitive decline, neurodegeneration, and paralysis without affecting tau pathology. Our findings show that the coding variant contributes to neuroprotection and suggest that TMEM106B is a critical safeguard against tau aggregation.

What Do Confessions Reveal About Abusive Head Trauma? A Systematic Review

Although confessions related to abusive head trauma (AHT) are reported, no detailed analysis exists. Therefore, we systematically reviewed studies of AHT confessions and examined the details, including country of origin, mechanisms and perpetrators' characteristics [PUBLISHER - THE PRECEDING UNDERLINED TEXT IS FOR THE MARGIN]. Employing 36 search terms across three search engines, we searched Medline and CINAHL from 1963 to 2018. All relevant studies underwent two independent reviews and data extraction. Descriptive statistics were used to characterise the sample; chi square and Fisher's exact tests were used to assess differences in demographic and clinical characteristics. Of 6759 identified studies, 157 full texts were reviewed and 55 articles from 15 countries spanning four continents were included. Included articles contained 434 confessions. The mechanisms of abuse included shaking alone (64.1%), impact alone (17.1%), shaking plus impact (18.0%) and other (0.9%). There was no statistically significant difference in the percentage of confessions reporting shaking alone when comparing continents: North America (64.0%), Europe (64.2%) and Oceania (60.0%; P=.92), or when comparing circumstances in which the confession was obtained: medical evaluation (74.6%) vs police or judicial investigations (63.4%; P=.11). Of 119 cases with identified perpetrators, 67.2 per cent were cases with males alone. Confessions reveal striking similarities in the mechanism of AHT (predominantly shaking) and occur across the globe.

Major complications associated with fork-based and screw-based tibial tuberosity advancement implants: 438 cases

This study reports major complications in a large cohort of dogs following tibial tuberosity advancement using either a fork-based or a screw-based implant system. Four hundred thirty-eight stifles were included in the study and major complications occurred in 51 stifles. Explanatory variables evaluated included implant type and body weight. No variables evaluated were associated with major complications.

Mimics of child abuse: Can choking explain abusive head trauma?

Choking is one of the alternative explanations of abusive head trauma in children that have been offered in courtroom testimony and in the media. Most of these explanations - including choking - are not scientifically supported. This article highlights four points. (1) The origins of choking as an explanation for intracranial and retinal hemorrhages are speculative. (2) Choking has been used in high profile court testimony as an explanation for the death of a child thought to have been abused. (3) A case report that proposes choking as an alternative explanation for the death of a child diagnosed with abusive head trauma includes omissions and misrepresentations of facts. (4) There was a decision by the editor of the journal that published the case report that it was not necessary to include all the facts of the case; moreover, the editor indicated that facts are not required when presenting an alternative explanation. The use of scientifically unsupported alternative explanations for abusive head trauma based on inaccurate and biased information constitutes further victimization of the abused child and represents a travesty of justice.

Use of a TTA Plate for Correction of Severe Patella Baja in a Chihuahua

A 7 yr old spayed female Chihuahua presented for right hind limb lameness and reduced stifle range of motion. Radiographs showed a marked patella baja of the right stifle and evidence of a previous surgery to correct a medial patellar luxation. A tibial tuberosity osteotomy was performed to allow proximal translation of the tibial tuberosity, which was stabilized with a tibial tuberosity advancement plate. Four weeks postoperatively, lameness and articular range of motion were improved, and the use of anti-inflammatory and analgesic medications was discontinued. The dog was still ambulating well and had no lameness 12 mo postsurgically.

Evaluation of photo-crosslinked fibrinogen as a rapid and strong tissue adhesive

Tissue adhesives and sealants are commonly used in surgery either as an adjunct to, or replacement for, sutures. Previously, we have shown that fibrinogen can be crosslinked rapidly to give a high-strength bond in the presence of a ruthenium(II) complex, a persulfate and irradiation with visible light, and that the crosslinked fibrinogen is nontoxic to cells in vitro. This approach addresses limitations to current fibrin sealants that typically have relatively slow curing times and low bond strengths. In the present study, we have evaluated the efficacy and safety of this new biological scaffold sealant in various animal models. When placed as solid implants into rats, the crosslinked fibrinogen persisted for at least 8 weeks but was fully resorbed by 18 weeks with minimal inflammatory responses. When used as a tissue adhesive for repair of skin incisions in rats or as an arterial haemostat in pig, the photo-crosslinked fibrinogen sealed tissue or arrested bleeding within 20 s of application. For the skin incisions, the fibrinogen sealant promoted rapid tissue vascularization and cellular infiltration with no adverse foreign body cell generation. New collagen deposition occurred and with time the matrix had remodelled to acquire large mature collagen fiber bundles which were accompanied by maximum regenerated tensile strength. This biomaterial system may find useful applications in surgical procedures where rapid curing and/or high strength tissue sealing is required.

Recurrent rectal prolapse caused by colonic duplication in a dog

A 9-month-old female Shar Pei cross-bred dog was presented with a history of recurrent rectal prolapse over 7 months. Repeated reduction and anal purse string sutures and subsequent incisional colopexy failed to prevent recurrent rectal prolapse. Digital rectal examination following reduction of the prolapse identified a faeces-filled sac within the ventral wall of the rectum and an orifice in the ventral colonic wall, cranial to the pubic brim. A ventral, communicating tubular colonic duplication was diagnosed by means of a barium enema. Surgical excision of the duplicated colonic tube was performed via a caudal ventral midline laparotomy. At 20 weeks post-operation, there has been no recurrence of rectal prolapse.

A retrospective study of unilateral arytenoid lateralisation in the treatment of laryngeal paralysis in 100 dogs (1992-2000)

OBJECTIVE

To determine the effectiveness of unilateral arytenoid lateralisation as a surgical treatment for laryngeal paralysis in dogs.

DESIGN

The case records of 100 dogs that received a unilateral arytenoid lateralisation for laryngeal paralysis between 1992 and 2000 were reviewed. The results of questionnaires on surgical outcome, formulated for the animal owner and the referring veterinarian, were analysed. Information obtained for dogs under 10 kg and dogs over 10 kg was analysed separately.

RESULTS

The Labrador Retriever was the most commonly affected breed. The male:female ratio was 1.56:1 and the average age of presentation was 9.9 years. The most common month in which surgery was performed was October. The majority of owners (87.7%) felt that their dog's quality of life was improved in the 6 months after surgery. Thirty-three percent of dogs revisited the referring clinic with a respiratory problem following unilateral arytenoid lateralisation, and 10.7% of dogs were reported as having a post-surgical complication associated with the procedure. Following surgery, dogs under 10 kg revisited the referring veterinarian with a respiratory complication more often than dogs over 10 kg. Significantly fewer owners of dogs under 10 kg than owners of dogs over 10 kg felt that their dogs quality of life was improved by surgery (55% versus 93%).

CONCLUSION

The majority of owners surveyed reported that unilateral arytenoid lateralisation had improved the quality of their dog's life during the first 6 postoperative months. Owner dissatisfaction with the results of surgery and the reported rate of re-presentation (for respiratory disease) may be higher for small (< 10 kg) dogs. A prospective study comparing the results of unilateral arytenoid lateralisation surgery in large and small dogs may be worthwhile in the future.

Efficacy of combined cyclosporine A and ketoconazole treatment of anal furunculosis

Cyclosporine A and ketoconazole were used as a combined therapy to treat 19 dogs with anal furunculosis. Complete resolution of all lesions was achieved in three to 10 weeks, but recurrences occurred in seven of the 19 dogs (36.8 per cent), with remission periods extending from one to six months for these dogs. Adverse effects of treatment included excessive hair loss, intermittent lethargy, vomiting and decreased appetite in some dogs, but none of the signs were considered serious. The results of treatment are comparable with, if not better than, the surgical alternatives. There is an approximate 70 per cent cost saving over the use of cyclosporine alone.

Evaluation of closed pericardial patch grafting for management of severe pulmonic stenosis

Closed pericardial patch-grafting has been advocated for the treatment of severe pulmonic stenosis. In this study pre- and postoperative echocardiography was used to determine if the transvalvular pressure gradient was successfully lowered by this surgery and whether it remained lowered long term. The valvulotomy-ventriculectomy wire was passed using a blunt needle in four dogs (Bresnock technique1) and via a soft catheter in five dogs (Shores and Weirich modification). Eight of nine patients survived the perioperative period. These dogs were assessed up to 40 months following surgery for clinical and echocardiographic changes. Five cases showed significant decrease in peak pulmonic pressure gradient immediately after surgery (decreasing by 50-81%, P < 0.05), and six cases showed significant decrease 2 to 40 months postoperatively (decreasing by 31-80%, P < 0.005) when compared to preoperative values. There was no significant change in pulmonic pressure gradient from immediately postoperatively to 2 to 40 months postoperatively (P < 0.48). Six dogs showed clinical improvement postoperatively, however persistent right ventricular hypertrophy was observed in all cases. One dog died with symptoms of congestive heart failure 16 months postoperatively. Closed pericardial patch grafting can improve clinical signs in symptomatic patients, however the surgery has significant risks, long term prognosis for these patients is guarded and recurrence of clinical signs and development of congestive heart failure is possible. Cardiac changes can be monitored with Doppler flow echocardiography. Patients with extremely elevated preoperative pressure gradients may be expected to have poorer outcomes.

Perioperative outcomes after three different single extrahepatic portosystemic shunt attenuation techniques in dogs: partial ligation, complete ligation and ameroid constrictor placement

OBJECTIVE

To compare the perioperative outcomes of single extrahepatic portosystemic shunt occlusion by complete and partial silk ligation and ameroid constrictor placement in dogs.

DESIGN

A retrospective analysis of 30 dogs with single congenital extrahepatic shunts.

PROCEDURE

Records between 1990 and 2000 were reviewed. Patient age, breed, weight, presenting clinical signs, clinical pathology results, diagnostic imaging results, the surgery procedure performed, implant used, time taken, intra operative complications and perioperative complications were recorded. Mortality rates were calculated.

RESULTS

Twenty dogs had a silk ligation procedure, 10 partially occluded and 10 completely. Ten dogs had an ameroid constrictor placement procedure. Ameroid constrictor surgery was significantly shorter in duration than silk ligation. Time for silk ligation was 91.8 +/- 35.2 minutes (median 90.0); time for ameroid constrictor placement was 71.5 +/- 12.0 (median 72.5, P = 0.049). A reduction in intraoperative complications was also noted in the ameroid constrictor surgery group.

CONCLUSION

The ameroid constrictor offered a surgical occlusion procedure of single extrahepatic portosystemic shunts in dogs that was clinically as effective as silk ligation in the perioperative period, with a significantly shorter surgery time.

Plastic particle migration during intravenous infusion assisted by a peristaltic finger pump in an animal model

The contamination of intravenously administered fluid with foreign material has always been of major concern, but the in-vivo impact of silicone embolisation from administration of fluid via a peristaltic finger pump (PFP) has not previously been assessed. To determine whether silicone particles enter the lungs and to review the histological response, 10 rabbits received an IV infusion of 0.9% saline at 10 ml/kg per hour over a 72-h period, via an IVAC 591 PFP. The lungs were analysed for silicone particles with scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDXA). These results were compared with a control group of non-infused animals. Silicone particles were found in 8 of 10 animals in the experimental group and in 2 of 9 control animals, indicating that silicone particles are dislodged during pump-assisted IV infusions. The difference between the control and infused animals was statistically significant using Fisher's exact test (P = 0.023). However, silicone plastic particles in control animals suggest that there is also environmental exposure to silicone in addition to those particles that come from a therapeutic source. The additional finding of elemental silicon (which is one of the constituents of silicone plastic) in both infused and control animals in which silicone plastic was not found indicates that not all elemental silicon in animals reflects the presence of silicone plastic. The clinical significance of each of these two findings is yet to be determined.

Lymphatic absorption is a significant contributor to the subcutaneous bioavailability of insulin in a sheep model

PURPOSE

This study was conducted to explore the role of the peripheral lymphatics in insulin absorption following subcutaneous (SC) administration using a sheep model that allows continuous collection of peripheral lymph and simultaneous assessment of systemic bioavailability.

METHODS

In a parallel group design, soluble human insulin (0.5 IU/kg) was administered by bolus SC injection into the interdigital space of the hind leg of non-cannulated control sheep, and sheep in which the efferent popliteal lymph duct was cannulated. A separate group received a bolus IV injection (0.15 IU/kg). Blood was sampled from all animals, and lymph was collected continuously over 12 h postdosing. Samples were assayed for insulin by ELISA.

RESULTS

The SC bioavailability of insulin in control sheep was 31.5+/-3.2%, which was significantly higher than when the peripheral lymph was continuously collected (18.4+/-1.7%). In the lymph-cannulated animals, 17.3+/-1.0% of the dose was collected in peripheral lymph.

CONCLUSIONS

Based on the direct measurement of insulin in regional lymph and on the decrease in the systemic bioavailability when regional lymph was continuously collected, the results demonstrate that lymphatic absorption contributed significantly to the overall insulin bioavailability following SC administration to sheep.

A conscious dog model for assessing the absorption, enterocyte-based metabolism, and intestinal lymphatic transport of halofantrine

Postprandial administration of halofantrine (Hf), an important antimalarial, leads to 3- and 12-fold increases in oral bioavailability in humans and beagles, respectively, and corresponding 2.4-fold and 6.8-fold decreases in metabolic conversion to desbutylhalofantrine (Hfm). Factors contributing to the decreased postprandial metabolism of Hf could include inhibition of presystemic CYP3A metabolism by food components and/or recruitment of the intestinal lymphatics as an absorption pathway. Although previous rat studies confirmed Hf base is a substrate for lymphatic transport, it is difficult to extrapolate such data to higher species, as the largely constant bile flow in a rat precludes attainment of representative pre- and postprandial states, and formulations administered to rats are often not relevant to higher species. These limitations have now been addressed by development of a conscious dog model that allows simultaneous study of intestinal lymphatic and nonlymphatic drug absorption and aspects of enterocyte-based drug metabolism. After oral administration of 100 mg Hf base, the mean fasted and postprandial lymphatic transport was 1.3% and 54% of the administered dose, respectively. Comparison of portal and systemic plasma Hfm concentration profiles suggested enterocyte-based conversion of Hf to Hfm; however, the proportion of Hf metabolized to Hfm was similar after fasted or postprandial administration. Hence, it appears that the previously observed decrease in the postprandial metabolism of Hf is largely a consequence of significant postprandial intestinal lymphatic transport (which bypasses first pass hepatic metabolism). This new dog model will facilitate identification of the key factors that impact bioavailability, lymphatic transport, and metabolic profiles of highly lipophilic drugs.

Animal models for the study of intestinal lymphatic drug transport

Drug transport via the intestinal lymphatic system has been shown to contribute to the absorption of a number of orally administered highly lipophilic drugs. In order to investigate this phenomenon and assist in the development of improved oral formulations, the use of appropriate animal models is required. This paper reviews the use of various animal models for this purpose, and describes in detail the conscious rat and dog models used in our laboratory. The advantages and disadvantages of both small and large animal models are explored, as well as the factors which have been found to influence the outcome of intestinal lymphatic drug transport studies with these models.

Lymphatic transport of proteins after s.c. injection: implications of animal model selection

Subcutaneous (s.c.) administration continues to be the main route for the delivery of protein drugs due to their poor bioavailability by most non-parenteral routes. While small drug molecules are rapidly and extensively absorbed after s.c. injection, the systemic bioavailability of protein drugs is often incomplete and variable. Given the widespread use of the s.c. route for protein drugs, surprisingly little is known about the factors that govern the rate and extent of protein absorption from the interstitial space and the role of the lymphatic system in the transport of these molecules to the systemic circulation. The few studies that have directly addressed the role of lymphatic transport in protein bioavailability are complicated by the use of methods and models that vary widely. In this review we will evaluate the available literature describing the lymphatic transport of proteins after s.c. injection and more specifically, address the impact of experimental variation (e.g. site of cannulation, animal model, anesthesia) on the interpretation of the data obtained. We will also describe in some detail the sheep model currently in use in our laboratory, which allows both estimation of the extent of uptake of protein drugs into the lymphatics draining the injection site, and quantification of the contribution of lymphatic transport to the absolute bioavailability.

Comparison of the effects of morphine administered by constant-rate intravenous infusion or intermittent intramuscular injection in dogs

OBJECTIVE

To compare physiologic and analgesic effects of morphine when given by IV constant-rate infusion or by IM injection to dogs undergoing laparotomy and to determine pharmacokinetics of morphine in dogs following IV constant-rate infusion.

DESIGN

Prospective randomized controlled trial.

ANIMALS

20 dogs.

PROCEDURE

Dogs undergoing laparotomy were treated with morphine beginning at the time of anesthetic induction. Morphine was administered by IV infusion (0.12 mg/kg/h [0.05 mg/lb/h] of body weight) or by IM injection (1 mg/kg [0.45 mg/lb]) at induction and extubation and every 4 hours thereafter. Treatments continued for 24 hours after extubation.

RESULTS

Blood gas values did not indicate clinically significant respiratory depression in either group, and degree of analgesia (determined as the University of Melbourne Pain Scale score) and incidence of adverse effects (panting, vomiting, defecation, and dysphoria) were not significantly different between groups. Dogs in both groups had significant decreases in mean heart rate, rectal temperature, and serum sodium and potassium concentrations, compared with preoperative values. Mean +/- SEM total body clearance of morphine was 68 +/- 6 ml/min/kg (31 +/- 3 ml/min/lb). Mean steady-state serum morphine concentration in dogs receiving morphine by constant-rate infusion was 30 +/- 2 ng/ml.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that administration of morphine as a constant-rate IV infusion at a dose of 0.12 mg/kg/h induced effects similar to those obtained with administration at a dose of 1 mg/kg, IM, every 4 hours in dogs undergoing laparotomy. Panting was attributed to an opioid-induced resetting of the hypothalamic temperature set point, rather than respiratory depression.

Diagnosis and management of cor triatriatum dexter in a Pyrenean mountain dog and an Akita Inu

Cor Triatriatum Dexter is a rare, congenital cardiac defect in which the right atrium is partitioned into two compartments, effectively creating a triatrial heart. The clinical signs exhibited by the patient usually relate to impeded venous return via the caudal vena cava. The two dogs in this report both displayed ascites from a young age and grew poorly. In both cases the diagnosis was made during echocardiographic examination and was confirmed by angiography. Both dogs were successfully treated by resection of the partitioning membrane within the right atrium, using hypothermia and inflow occlusion to achieve a clear surgical field. Both dogs recovered well, their clinical signs resolved and they have grown to normal adult size.

Phased-Array intracardiac echocardiography to guide radiofrequency ablation in the left atrium and at the pulmonary vein ostium

INTRODUCTION

We sought to evaluate the utility of a phased-array intracardiac echocardiography (ICE) device to identify left atrial (LA) and pulmonary vein (PV) anatomy; accurately guide radiofrequency ablation (RFA) to the right or left PV ostium and LA appendage (LAA); and evaluate PV blood flow before and after RFA using Doppler parameters.

METHODS AND RESULTS

Twelve adult sheep were anesthetized and an Acuson 10-French, 7-MHz ICE transducer introduced via the internal jugular vein into the right atrium. The LA was imaged and PV anatomy and blood flow documented using two-dimensional and pulsed-wave Doppler. Mean LA dimensions were 4.6 +/- 0.4 x 3.5 +/- 0.5 cm; mean single right and left main PV ostium diameters were 1.5 +/- 0.2 and 1.3 +/- 0.3 cm; and mean right and left PV first-order branch diameters were 0.8 +/-0.2 and 0.6 +/- 0.1 cm. Mean PV maximum inflow velocity for the right PV were 0.30 +/- 0.05 m/sec and for the left PV were 0.35 +/- 0.04 m/sec. The PV ostia and LAA could be targeted accurately for RFA using ICE guidance. At pathologic evaluation, the mean distance of the lesion center to the right or left PV-LA junction was 3.0 +/- 2.0 mm. The mean distance of the lesion center to the posterior margin of the LAA was <4 mm in all cases. There was no significant increase in PV maximum inflow velocity or decrease in PV diameter following RFA at the PV ostium. Absence of PV obstruction was confirmed at pathology.

CONCLUSION

Phased-array ICE allows detailed assessment of LA and PV anatomy when imaged from the right atrium; accurate guidance of RFA to the PV ostium and LAA; and immediate evaluation of PV patency after RFA.

The development of a pig model to study fetal vesico-ureteric reflux

OBJECTIVE

To develop a surgical protocol to induce vesico-ureteric reflux (VUR) in utero by ablating the ureteric tunnel in a fetal pig model.

MATERIALS AND METHODS

Fetal surgery was conducted on nine sows, which were divided into three groups according to changes in the surgical protocol. Sows in groups 2 and 3 received different anaesthetics and antibiotics, and the operating theatre temperature was increased. In all cases, the intramural part of the ureter was unroofed in the fetuses, which were then returned to the uterus. Upon delivery, cystograms were taken in the male piglets, and the urinary tracts removed for anatomical and histological examination.

RESULTS

All three sows in group 1 delivered healthy piglets, but the fetuses that had undergone surgery were mummified. In group 2 the animals survived the fetal intervention, as shown by ultrasonography after surgery, but the four sows aborted spontaneously within a week. In group 3, both sows delivered normally developed piglets, three of which had undergone ablation of the ureteric tunnel. VUR was present only in those renal units in which the ureteric tunnel was ablated, and this was associated with hydronephrosis, dilatation of the ureters and thinning of the renal parenchyma on gross pathological examination.

CONCLUSIONS

The fetal pig model of VUR not only appears to be feasible, but with similarities in renal anatomy and physiology also seems to be ideal for investigating fetal VUR.

Voiding cystourethrograms and urinary tract infections: how long to wait?

OBJECTIVES

Many authorities recommend an interval of at least 3 to 6 weeks after a urinary tract infection (UTI) before performing a voiding cystourethrogram (VCUG). However, such an interval may reduce the likelihood of completing the procedure. This study was performed to investigate whether the length of the interval between a UTI and the performance of the VCUG influences the presence or severity of reflux, and whether it influences the likelihood of actually having the study performed.

DESIGN

We reviewed 352 admissions of children under 10 years old whose discharge diagnoses indicated UTIs. These admissions occurred over a 27-month period between October 1994 and December 1996 at the Children's Hospital of Austin, Texas. We identified 213 patients with confirmed UTIs and no other previously defined urinary tract pathology. These patients were divided into 2 groups according to whether they had a VCUG scheduled to be performed either within 1 week after the diagnosis of a UTI (the early group), or later than 1 week after the diagnosis (the late group). We compared the presence and severity of reflux in the 2 groups as well as the proportion of scheduled VCUGs that were actually performed.

RESULTS

Reflux was present in 19% of the patients studied within 1 week after UTI (95% confidence interval [CI]: 12.9-26.4) and in 18% of those studied after 1 week (95% CI: 6. 7-34.5). This difference was not statistically significant (chi(2) =. 034; DF = 1). However there was a substantial difference between the 2 groups with regard to the number of scheduled VCUGs actually performed. Whereas 100% of the scheduled VCUGs in the early group were performed, only 48% (95% CI: 35.9-60.1) of those scheduled in the late group were performed. This difference is statistically significant (chi(2) = 89.6; DF = 1).

CONCLUSIONS

In the hospitalized children who underwent VCUGs within a week after diagnosis of UTI, the presence of reflux is not significantly different from those studied later. Furthermore, late scheduling of VCUGs resulted in failure to perform the procedure in more than half of the patients. Some of the patients who were not evaluated would be expected to have vesicoureteral reflux and thus be at risk for chronic renal disease. Therefore, the traditional recommendation to perform the VCUG at 3 to 6 weeks after the diagnosis of UTI should be reconsidered, especially for hospitalized children.

Systemic availability and lymphatic transport of human growth hormone administered by subcutaneous injection

Degradation of human growth hormone (hGH) at the injection site has previously been implicated as the basis for its reduced systemic availability following subcutaneous (SC) administration. The goal of these studies was to develop an animal model which would allow mass balance calculations to (i) quantify the loss at the injection site and (ii) determine the role of the lymphatics in the transport of subcutaneously-administered hGH. The animal model utilized a sheep and enabled simultaneous sampling of blood and collection of either peripheral lymph (via the efferent duct of the popliteal lymph node draining the injection site) or central lymph (via the thoracic lymph duct). In non-lymph cannulated sheep, the systemic availability of hGH following SC dosing was 58.4 +/- 9.1% (mean +/- SEM) relative to an intravenous (IV) control. The availability of hGH decreased to approximately 30-40% when either peripheral or central lymph was collected indicating that a proportion of the dose was transported via the lymph. The fraction of the administered dose collected in peripheral lymph was 61.7 +/- 8.5% (mean +/- SEM), whereas only 8.6 +/- 1.3% was collected in central lymph. These results suggested that loss of hGH within the lymphatics contributed significantly to its reduced systemic availability following SC administration. The total recovery (sum of the systemic availability and the cumulative amount recovered in lymph) of hGH was approximately 93% of the dose in the peripherally-cannulated group indicating that loss at the injection site was minimal.

Effects of mesh modification on the structure of a mandrel-grown biosynthetic vascular prosthesis

Mandrel-grown, mesh-reinforced vascular prostheses require adequate tissue coverage of the mesh for effective clinical function, particularly in low blood flow situations. Development of the ovine collagen-based Omniflowtrade mark vascular prosthesis has shown that the extent of this tissue cover is dependent on the interactions of the mandrel and the mesh with the sheep host. In the present study, the effects of chemical changes to the mesh have been examined. These data indicate that certain treatments of the mesh, particularly collagen or heparin, lead to increased tissue coverage while the number of sheep cells present and the ultrastructure of the resulting vessel remain unchanged.

In vivo evaluation of modified mandrel-grown vascular prostheses

The Omniflowtrade mark Vascular Prosthesis (OVP) has been manufactured and extensively tested in animal and human trials. It has mechanical and biological qualities superior to synthetic and biological conduits, particularly in low flow conditions. For further development into the smaller diameter coronary prostheses, the inner luminal surface is of paramount importance. In a previous study this inner surface was modified to produce a more uniformly thicker nonundulating surface. In this study the mandrels of these modified OVPs were treated with either collagen or heparin; the OVPs were evaluated for patency, tissue integration and wound healing, and endothelialization using a dog model comparable to that used to evaluate the unmodified OVP. In all instances, each of the modified prostheses were fully patent and had no signs of any deleterious effects caused by these modifications; no thrombus or aneurysms were visible. The tissue response was rapid with excellent new host collagen deposition within the vessel wall and minimal inflammatory and foreign body giant cells. Endothelialization was noted at the earliest explant time point in central regions of the prostheses, albeit that the histological picture at this time point appeared to reflect a complex atypical intimal layer.

Can some physical therapy and manual techniques generate potentially osteogenic levels of strain within mammalian bone?

BACKGROUND AND PURPOSE

Although physical therapy techniques are used to alleviate pain and stiffness in joint injuries, whether these methods are capable of affecting bone is unknown. For example, can these techniques potentially influence bone formation or resorption? To begin exploring this possibility, this study investigated the ability of 4 manual techniques to generate levels of compressive strains that presumably can stimulate bone metabolism.

SUBJECTS

Six 3,4 metacarpals from three 3-year-old Merino ewes were used.

METHODS

A rosette strain gauge was implanted onto the dorsomedial cortex of each ovine 3,4 metacarpal. Four different manual procedures were applied on 2 occasions on each metacarpal in vivo and ex vivo. Mean peak principal compressive strains were calculated for each technique.

RESULTS

Levered bending produced greater mean peak compressive strains than almost all other manual procedures tested in vivo or ex vivo.

CONCLUSION AND DISCUSSION

Manual levered bending created levels of compressive strain similar in magnitude to those created by mechanical devices used in previous animal experiments to induce new bone formation (osteogenesis). This animal model appears to be suitable for investigating the effects of manually applied procedures on bone and may establish whether manual techniques can stimulate bone formation.

Ureteric tunnel incision in the fetal pig: a model for non-obstructive prenatal vesicoureteric reflux

The understanding of vesicoureteric reflux (VUR) continues to improve, particularly as the renal tract can now be assessed prenatally. To further study the evolution of fetal renal changes, we studied two neonatal piglets that had undergone midgestation ureteric tunnel ablation. Dilatation of the pelvicalyceal system was seen radiologically and macroscopically in all three kidneys into which VUR had been created. Despite the study being marred by poor fetal survival, the results indicate that the model should be developed further to explore what appears to be an interrelationship between VUR and renal parenchymal changes in utero.

Metabolism of halofantrine to its equipotent metabolite, desbutylhalofantrine, is decreased when orally administered with ketoconazole

Halofantrine (Hf) is a highly lipophilic antimalarial with poor and erratic absorption. Published data indicates that the oral bioavailability of Hf was increased 3-fold in humans and 12-fold in dogs when administered postprandially; however, the proportional formation of the active desbutyl metabolite (desbutylhalofantrine, Hfm) decreased 2.4-fold in humans and 6.8-fold in dogs (Milton et al., Br. J. Clin. Pharmacol. 1989, 28, 71-77; Humberstone et al., J. Pharm. Sci. 1996, 85, 525-529). The current study was undertaken to confirm the putative involvement of CYP3A4 in the N-dealkylation of Hf to Hfm by administering Hf with and without ketoconazole (KC), a specific CYP3A4 inhibitor, and measuring the resulting plasma concentration profiles of Hf and Hfm. The plasma Hfm/Hf AUC(0-72 h) ratio after fasted oral administration of Hf without KC was 0.56, whereas the ratio after fasted oral administration with KC was less than 0.05. It is likely that both hepatic and prehepatic (enterocyte-based) CYP3A4 contributed to metabolism of Hf to Hfm after oral administration. Interestingly, the low plasma Hfm/Hf AUC ratios observed after fasted administration of Hf with KC were similar to the low values previously observed when Hf was administered postprandially (despite increased Hf absorption). The mechanism(s) by which postprandial administration of Hf led to a decrease in its metabolism are unknown, but based on the current data, could include inhibition of CYP3A4-mediated metabolism by components of the ingested meal. Other possibilities include a lipid-induced postprandial recruitment of intestinal lymphatic transport or avoidance of metabolism during transport through the enterocyte into the portal blood. Further studies are required to determine the relative contributions by which these different processes may decrease the presystemic metabolism of Hf.

Association of halofantrine with postprandially derived plasma lipoproteins decreases its clearance relative to administration in the fasted state

The oral bioavailability of halofantrine (Hf), a highly lipophilic phenanthrenemethanol antimalarial, is significantly enhanced when ingested with food. Although food enhances the absorption of Hf, it also alters the intrinsic pharmacokinetics of Hf as the observed postprandial absolute bioavailability was greater than 100% (Humberstone et al., J. Pharm. Sci. 1996, 85, 525-529). In this study, the association of Hf with plasma lipoproteins and the effect of postprandial lipoproteins on the pharmacokinetics of Hf after intravenous administration was examined in beagles. In fasted dogs, approximately 50% of plasma Hf was associated with lipoproteins, with HDL accounting for 42-43%, LDL for 4-5%, and triglyceride rich lipoproteins (TRL) for 2-3%. At 0.5 and 2 h postdosing in the postprandial state, the proportion of Hf present in both TRL and LDL increased to 7-10%. Changes in Hf distribution between lipoprotein fractions reflected the respective postprandial changes in plasma triglyceride (TG) concentrations. In terms of pharmacokinetics, when an equivalent dose of Hf was administered intravenously in a crossover study to fed and fasted beagles, plasma Hf AUC values were significantly higher, and CL and Vss were significantly lower, in the fed state compared to the fasted state (p < 0.05). The mean postprandial increase in plasma AUC values was 19% (range 14-34%), with corresponding decreases in CL (15%) and Vss (21%). A broadly linear relationship between increased postprandial Hf concentrations at specific time points (fed vs fasted) and corresponding postprandial increases in TG concentrations suggested that the decreased postprandial clearance of Hf was a function of increased association with TG-rich plasma lipoproteins. This study confirms that the clearance of Hf is influenced by plasma lipoprotein profiles, and the findings have implications for the design and interpretation of fed/fasted bioavailability studies of lipophilic drugs and determination of their intrinsic pharmacokinetic parameters in subjects or patients with dyslipidemic profiles.

Evaluation of a collagen-based biosynthetic material for the repair of abdominal wall defects

A collagen tissue polymer composite manufactured in sheep and prepared in two different forms (wet and dry) was compared to polypropylene mesh and to a control group for effectiveness in the repair of an abdominal wall defect in a rabbit model. The wet and dry patches were shown to differ significantly in their pore size. The wet material was shown to retain its natural porosity and promoted neovascularization, tissue integration, cellular infiltration, and neomatrix formation compared to the dry collagen-polymer patch. This material was superior to the polypropylene mesh implant, which was associated with significant adhesions. The appearance of type VI collagen was the earliest sign of new cell infiltration and neomatrix formation within the implant. New deposition of type VI collagen was apparent throughout the thickness of the implant within 4 weeks, followed by type III collagen accumulation. Decreased porosity of the collagen component in the dry patches resulted in a totally nonintegrated implant. This induced a foreign-body capsule with minimal cellular tissue infiltration and no deposition of collagen types VI and III within the implant.

In vivo evaluation of a collagenous membrane as an absorbable adhesion barrier

An absorbable membrane made from purified, pepsin-soluble collagen was compared to Interceed, an absorbable cellulose-based product, and to a control group for effectiveness in inhibiting the formation of adhesions between peritoneal surface injuries in adult rats. An adhesion scoring system was used to evaluate and compare the performance of the test materials with the control group in regard to the extent, tenacity, and type of any adhesions evident at 28 days following surgery. The collagen group performed significantly better (p < 0.05) than either the Interceed or control groups, showing fewer, less extensive adhesions. The collagen membranes resulted in either no or weak adhesions between the body wall and caecum. Adhesions in the Interceed group were quite variable and characterized by a marked peritoneal reaction in the caecal and body walls adjacent to adhesions. Control samples were characterized by close, dense fibrotic adhesions between the caecum and body wall. Both of the test materials showed some deficiencies in respect to their physical and handling properties that could be further improved for this indication.

Business modeling tools for managing decision support systems

We sought to investigate the role of business modeling tools in facilitating the implementation of interactive decision support systems (DSS) for laboratory test ordering. We have recently shown that Ripple Down Rules (RDR), a new strategy for building expert systems (ES), enables institutions to build DSS maintained by local experts without knowledge engineering support. While DSS hold great promise for improving health outcomes by providing doctors with timely access to care guidelines, implementation will require careful planning and change management. The Situated, Strategic, and AI-Enhanced method was used to define and assess a DSS-driven process change. DECmodelTM, a graphical business modeling application, was used to build representations of current (paper-based) and future (ES-supported) test ordering environments. Models described both the interactions between new processes and the impact on healthcare quality of ES-supported DSS. Models were able to represent the key processes involved in test ordering and the impact of DSS. Users could interact with the model to examine the time and cost implications of the transition from current to future states. The level of detail in which processes could be examined was readily controlled by the user. We have shown that graphical business modeling applications are useful tools for enabling institutions to view the impact of DSS. Accuracy of models should be maximized in workshops involving key management personnel. Whilst the impact of modeling on the cost and quality of DSS implementation remains to be established, we believe these tools are valuable for institutions planning to align DSS technologies to their service needs.

Early performance appraisal of the Omniflow II Vascular Prosthesis as an indicator of long-term function

The search for the ideal vascular prosthesis for below the knee replacement or coronary surgery continues. Long-term explant analysis of a biosynthetic composite vessel, the Omniflow Vascular Prosthesis I, has previously shown sound structural durability. An important determinant in defining durability has been the evaluation of the degree of persistence of the original biological components and the augmentation by new tissue. The development of a panel of specific monoclonal antibodies to collagens, that allow detection of new host collagen among the original collagens of the prosthesis has been a key factor. In the present study, these antibodies have been used to investigate the degree and rate of new collagen tissue infiltration in an improved version of the Omniflow prosthesis. The data show that new collagen types III and VI can be detected as early as 3 months in the adventitial tissue, and that complete tissue augmentation throughout the entire vessel wall is apparent by 6 months after implant. The novel explant analyses serve as a good predictive indication to the in vivo performance of the device and would be useful in rapid monitoring of further modifications to this vessel or to other collagen-based prostheses.