Re-visiting the ATA 2015 sonographic guidelines - who are we missing?: A retrospective review

BACKGROUND

The American Thyroid Association published revised guidelines in 2015 on the management of differentiated thyroid cancer in adults. One of the key changes introduced in the revision proposes that diagnostic biopsy be based on ultrasound findings (i.e. size and nodule characteristics). The overall effect of these changes results in fewer nodules requiring biopsy. This study was conducted to determine if the changes to the guidelines will result in overlooked thyroid cancers, specifically malignancies with aggressive characteristics measuring between 1 and 1.49 cm.

METHODS

Patients (n = 2083) with thyroid nodules who underwent total or subtotal/hemi thyroidectomy with or without neck dissection by a single surgeon between 2006 and 2016 were retrospectively enrolled. Demographic information and nodule characteristics were collected for all patients. Ultrasonography and final pathology reports were reviewed for patients with thyroid nodules between the sizes of 1-1.49 cm (n = 155).

RESULTS

45% (n = 70) of patients with nodules between 1 and 1.49 cm were "low suspicion" nodules according to ultrasound. 47 of these nodules contained malignancies on final histopathological examination, 100% of which were of the papillary subtype. 21% (n = 10) of these malignant nodules demonstrated extrathyroidal extension and 34% (n = 16) were associated with regional metastases.

CONCLUSIONS

Reliance on sonographic patterns alone could result in missed cancer diagnoses in patients with thyroid nodules measuring between 1 and 1.49 cm. Moreover, a portion of these malignancies may be associated with aggressive features. The effect of this finding on long-term outcomes is unclear.

Structural requirements of flavonoids to induce heme oxygenase-1 expression

Population studies suggest cardiovascular health benefits of consuming fruits and vegetables rich in polyphenolic compounds such as flavonoids. We reported previously that the flavonoid quercetin protects arteries from oxidant-induced endothelial dysfunction and attenuates atherosclerosis in apolipoprotein E gene knockout mice, with induction of heme oxygenase-1 (Hmox1) playing a critical role. The present study investigated the structural requirements of flavonoids to induce Hmox1 in human aortic endothelial cells (HAEC). We identified ortho-dihydroxyl groups and an α,β-unsaturated system attached to a catechol as the key structural requirements for Hmox1 induction. Active but not inactive flavonoids had a low oxidation potential and prevented ascorbate autoxidation, suggesting that Hmox1 inducers readily undergo oxidation and that oxidized, rather than reduced, flavonoids may be the biological inducer of Hmox1. To test this hypothesis, we synthesized stable derivatives of caffeic acid (3-(3,4-dihyroxyphenyl)-2-propenoic acid) containing either ortho-dihydroxy or ortho-dioxo groups. Compared with the dihydroxy compound, the quinone analog induced Hmox1 more potently in HAEC and also provided enhanced protection to arteries of wild type animals against oxidant-induced endothelial dysfunction. In contrast, the quinone analog failed to provide protection against oxidant-induced endothelial dysfunction in arteries of Hmox1^-/- mice, establishing a key role for Hmox1 in vascular protection. These results suggest that oxidized forms of dietary polyphenols are the likely inducers of Hmox1 and may explain in part the protective cardiovascular effects of diets rich in these compounds.

Fracture of the medial intercondylar eminence of the tibia in horses treated by arthroscopic fragment removal (21 horses)

BACKGROUND

Fractures of the medial intercondylar eminence of the tibia (MICET) are scarcely reported in horses.

OBJECTIVES

To report the clinical and diagnostic findings, surgical treatment and outcome in a series of horses presented with MICET fracture and treated with arthroscopic fragment removal.

STUDY DESIGN

Multicentre retrospective case series.

METHODS

Case records of horses diagnosed with MICET fractures that had undergone surgical treatment were reviewed. Follow-up information was obtained from re-examination visits and/or owners.

RESULTS

Twenty-one cases were identified at 9 equine hospitals between 2004 and 2016. A history of trauma and acute onset of lameness was reported in 12 horses. All cases underwent fracture removal via arthroscopy of the medial femorotibial joint. The cranial cruciate ligament was intact in 6 horses and damaged in 15 horses (damage was ≤25% [n = 9], 25-50% [n = 4] or ≥50% [n = 2] of the cross-sectional area). The cranial ligament of the medial meniscus was damaged in 11 horses (≤25% [n = 8], 25-50% [n = 3]). The medial meniscus was damaged in 5 horses and articular cartilage damage was identified in 14 horses (mild [n = 8], moderate [n = 6]). Follow-up information (median 14 months; 4 months-6 years) was available for 20 cases; 2 horses were sound but convalescing; 13 horses were sound and returned to their previous or expected use. Of the 4 horses with the most severe changes to the articular soft tissue structures, 2 remained lame and 2 were subjected to euthanasia because of persistent lameness.

MAIN LIMITATIONS

The retrospective, multicentre nature of this study and the limited number of horses are the main limitations.

CONCLUSIONS

Fractures of the MICET are commonly associated with a traumatic event. Prompt diagnosis and early arthroscopic removal of the fracture are recommended.

Clinicopathological relevance of antithyroglobulin antibodies in low-risk papillary thyroid cancer

OBJECTIVE

The extent of initial surgical management in papillary thyroid cancer (PTC) is controversial. We examined whether the presence of perioperative antithyroglobulin antibodies (TGA) could predict long-term recurrence and occurrence of adverse features among a homogenous group of patients with PTC.

METHODS

The clinical features of patients with PTC treated at a single institution (Jewish General Hospital, McGill University, Montreal, Canada) were obtained from the medical records, and all clinicopathologic information was reviewed. Only low-risk PTC without clinical evidence of nodal disease before surgery and treated with 30 mCi of radioactive iodine was included in the study.

RESULTS

The chart review retrieved 361 patients with a median follow-up of 85.0 months (Q25-Q75 73-98). Forty-two (11.6%) patients had presence of perioperative TGA. Perioperative TGAs were associated with present extrathyroidal extension (P=.005), unsuspected nodal disease (P=.001) and autoimmune thyroiditis (P<.0001). Overall, 17 (4.7%) patients experienced locoregional recurrence. Perioperative TGAs were a significant predictor of recurrence in univariable (P=.021) but not in multivariable analysis (P=.13).

CONCLUSION

Presence of perioperative TGAs is associated with aggressive histological features and the presence of thyroiditis. Detection of TGA perioperatively may encourage surgeons to consider more extensive initial surgery.

Can preoperative thyroglobulin antibody levels be used as a marker for well differentiated thyroid cancer?

Background

It has been reported that thyroglobulin antibody are more frequently elevated in patients with thyroid cancercompared to general population. This study aims at evaluating whether preoperative thyroglobulin antibody (TgAb) levels increase the likelihood that a thyroid nodule is malignant.

Methods

A retrospective review of 586 patients who underwent thyroidectomy was conducted. Demographic data, TgAb levels, and final histopathology were recorded. Patients were divided into two groups: TgAb positive (defined as TgAb ≥ 30 IU/ml) and TgAb low/negative (defined as TgAb < 30).

Results

Preoperative TgAb levels were available in 405 patients. There were 353 (87 %) patients in the TgAblow/negative group (malignancy rate: 50.42 %) and 52 (13 %) patients in the TgAb positive group (malignancy rate: 65.38 %). The sensitivity, specificity, positive predictive value and negative predictive value of TgAb ≥ 30 IU/ml for thyroid malignancy were 16.04 %, 90.67 %, 65.38 % and 49.58 %, respectively. The relative risk of having a malignant thyroid nodule when the TgAb titers were≥30 IU/ml was 1.30 (CI1.04-1.62) and the odds ratio was 1.86 (CI 1.01-3.41). Both the Pearson chi-square test (p = 0.024) and Fisher’s exact test (p = 0.017) yielded statistical significance between the two groups.

Conclusions

In this study, patients with preoperative TgAb ≥ 30 IU/ml had a higher rate of malignancy when compared topatients with TgAb < 30 IU/ml. This suggests that an elevated TgAb level may indicate that a thyroid nodule is at an increased risk for malignancy.

Short- and long-term results following standing fracture repair in 34 horses

REASONS FOR PERFORMING STUDY

Standing fracture repair in the horse is a recently described surgical procedure and currently there are few follow-up data. This case series contains 2 novel aspects in the standing horse: repair of incomplete sagittal fractures of the proximal phalanx and medial condylar repair from a lateral aspect.

OBJECTIVES

To describe outcome in a case series of horses that had lower limb fractures repaired under standing sedation at Rossdales Equine Hospital.

METHOD

Case records for all horses that had a fracture surgically repaired, by one surgeon at Rossdales Equine Hospital, under standing sedation and local anaesthesia up until June 2011, were retrieved. Hospital records, owner/trainer telephone questionnaire and the Racing Post website were used to evaluate follow-up.

RESULTS

Thirty-four horses satisfied the inclusion criteria. Fracture sites included the proximal phalanx (incomplete sagittal fracture, n = 14); the third metacarpal bone (lateral condyle, n = 12, and medial condyle, n = 7); and the third metatarsal bone (lateral condyle, n = 1). One horse required euthanasia due to caecal rupture 10 days post operatively. Twenty horses (66.7% of those with available follow-up) have returned to racing. Where available, mean time from operation to return to racing was 226 days (range 143-433 days).

CONCLUSIONS

Standing fracture repair produced similar results to fracture repair under general anaesthesia in terms of both the number of horses that returned to racing and the time between surgery and race.

POTENTIAL RELEVANCE

Repair of lower limb fracture in the horse under standing sedation is a procedure that has the potential for tangible benefits, including avoidance of the inherent risks of general anaesthesia. The preliminary findings in this series of horses are encouraging and informative when discussing options available prior to fracture repair.

Outcome and long-term follow-up of 20 horses undergoing surgery for caecal impaction: a retrospective study (2000-2008)

REASONS FOR PERFORMING STUDY

If untreated, caecal impaction may progress to rupture of the caecum and reports of long-term outcome for horses undergoing surgery for caecal impaction are required.

OBJECTIVES

To describe short- and long-term complication rates for horses undergoing surgery for caecal impaction in an otherwise life-threatening gastrointestinal condition.

METHODS

Case records were reviewed for horses undergoing surgery for caecal impaction. Horses were included in the study if an abnormally large, fluid-distended or feed-impacted caecum was the primary diagnosis at surgery and excluded if the caecum had already ruptured upon opening the abdomen, necessitating euthanasia. Short-term follow-up data were obtained from clinical records; and included complications, repeat celiotomy and survival to discharge. Long-term survival was defined as survival for >1 year post operatively. Long-term follow-up data were obtained through telephone interviews with owners and referring veterinary surgeons. Survival, occurrence of post operative colic and subsequent use of the horse were recorded.

RESULTS

Twenty horses underwent surgery for caecal impaction: 16 horses underwent caecal bypass (typhlotomy and removal of caecal contents, ileal transection followed by ileocolostomy); 3 underwent typhlotomy alone; and one horse underwent typhlotomy followed by a second procedure where caecal bypass was performed. Five horses (25%) were admitted for colic evaluation with primary caecal impactions, in 10/20 (50%) of cases the impaction was secondary to previous orthopaedic surgery and in 5/20 (25%) caecal impaction was identified at repeat celiotomy following a previous colic surgery. Sixty-five percent (13/20) of horses survived to discharge; 11/13 (85%) of horses discharged survived long term; 100% (3/3) horses that received typhlotomy alone were discharged and survived long term.

CONCLUSIONS

The prognosis following caecal impaction surgery is fair, if the horse survives to discharge then prognosis for long-term survival is good.

POTENTIAL RELEVANCE

Surgery for caecal impaction carries a fair prognosis for a potentially life threatening disease, in particular where caecal dysfunction is suspected.

Osteoarthritis of the talocalcaneal joint in 18 horses

REASONS FOR PERFORMING STUDY

Talocalcaneal osteoarthritis (TO) is an uncommon cause of moderate to severe hindlimb lameness, on which only isolated case reports have been published to date.

OBJECTIVES

To review the clinical features of TO and determine optimal methods for diagnosis, management and prognosis.

METHODS

The case records from 4 referral centres of 18 horses showing hindlimb lameness considered, as a result of clinical investigation, to be caused by TO, were reviewed.

RESULTS

TO affected mature sports and pleasure horses (age 7-16 years) and caused moderate to severe lameness, usually of sudden onset with no obvious inciting cause. There were few localising signs, other than worsening of lameness by hock flexion. Tarsocrural joint analgesia produced improvement in lameness in 6/11 horses (55%) and perineural analgesia of the tibial and fibular nerves complete soundness in 6/14 horses (43%) in which it was performed; 7/14 horses (50%) showed a further substantial improvement. Radiological findings included subchondral bone lysis and sclerosis and irregular joint space width, seen most obviously in a lateromedial view. Nuclear scintigraphy revealed marked uptake of radiopharmaceutical predominantly plantaromedially in the region of the talus in the 7 horses in which it was performed. Fourteen horses were treated conservatively with box- or pasture-rest, with or without intra-articular corticosteroids, hyaluronic acid or polysulphated glycosaminoglycan, and all remained lame. Intra-articular corticosteroids appeared to have no effect in any horse. Of 10 horses receiving conservative management only, 6 were subjected to euthanasia, 3 were retired and 1 remained in light work, but was still lame. Two horses treated by either partial tibial and fibular neurectomy or subchondral forage failed to regain soundness and were retired. Six horses were treated by surgical arthrodesis of the talocalcaneal joint with 2 or three 5.5 mm AO screws introduced obliquely across the joint from the plantarolateral aspect of the calcaneus, which resulted in improvement in lameness in all cases.

CONCLUSIONS

Osteoarthritis of the talocalcaneal joint causes acute onset severe lameness, but clinical findings and diagnostic analgesia often fail to identify precisely the site of pain. Consistent radiographic changes suggested TO was contributing to the lameness and this diagnosis was supported by nuclear scintigraphy. The poor success of conservative treatment (including intra-articular medication) suggests that surgical arthrodesis is the treatment of choice, although the prognosis is still poor for a return to full soundness.

POTENTIAL RELEVANCE

The clinical features described should facilitate more accurate diagnosis and prognosis. A novel surgical treatment is described which appears to offer significant improvement in the lameness. Further work is necessary to determine the causes of this condition and more effective management.

Electrosurgery as the sole means of haemostasis during the laparoscopic removal of pathologically enlarged ovaries in mares: a report of 55 cases

REASONS FOR PERFORMING STUDY

There is little published clinical evidence on the use of a laparoscopic approach for the removal of pathologically enlarged ovaries in standing mares.

OBJECTIVES

To show the orders of success and complication rates that can be expected if pathologically enlarged ovaries are removed from standing, sedated mares under laparoscopic guidance using only electrosurgical means of haemostasis.

METHODS

A retrospective analysis was made of 55 mares in which the removal of an enlarged ovary was attempted by applying a standard laparoscopic procedure for routine ovariectomy in standing mares including a reliance solely on one of 2 types of electrosurgical bipolar forceps with an integrated guillotine for haemostasis and transection of the ovarian pedicle. The outcomes and complications encountered were recorded. Logistic regression analysis was performed to identify the risk of any complications associated with the size of the ovary removed and the instrument used.

RESULTS

In 54 of the 55 mares, the surgery was successfully accomplished by the planned approach. In one mare there was significant intraoperative haemorrhage and this necessitated the additional use of a prosthetic haemostatic device. The only other complications encountered were post operative abdominal discomfort (n = 9), delayed incisional wound healing (n = 6) and iatrogenic uterine puncture (n = 2). One mare developed a rectal tear, but not as a direct complication of the surgical procedure. None of these prevented a long-term successful outcome.

CONCLUSIONS

The removal of pathologically enlarged ovaries (up to 30 cm diameter) from mares under standing sedation can be accomplished predictably and safely by applying the standard laparoscopic approach that is established for routine laparoscopic ovariectomy, including a reliance solely on endoscopic electrosurgery instruments for haemostasis of the ovarian pedicle.

POTENTIAL RELEVANCE

This study shows that the simple standing laparoscopic technique now favoured for routine ovariectomy can be used safely and reliably for the removal of pathologically enlarged ovaries. This promises to be of significant clinical advantage to mares so affected.

What is the likelihood that Thoroughbred foals treated for septic arthritis will race?

REASONS FOR PERFORMING STUDY

Septic arthritis is a serious problem in the neonate, with a poor prognosis being reported for recovery. The impact of neonatal septic arthritis on the likelihood that Thoroughbred (TB) foals will start on a racecourse is not known.

HYPOTHESIS

The development of septic arthritis in a TB foal significantly reduces the likelihood that it will race when compared to foals from the same dam.

METHODS

Medical records of 69 foals treated for septic arthritis were reviewed. The dam's foaling records were reviewed and lifetime racing records were then retrieved for both the affected foals and at least one of their siblings (controls). Outcomes that were statistically evaluated included discharge from the hospital and whether the foal eventually raced. Univariate analyses of categorical variables were conducted for each outcome. The number of affected and unaffected foals that raced at least once were compared using regression analysis. Survival analysis was used to compare age at first race between the study and comparison groups.

RESULTS

Foals with septic arthritis were less likely to start on a racecourse compared to controls (odds ratio [OR] 0.28; 95% confidence interval [CI] 0.12-0.62, P = 0.001), while those foals that were discharged from the hospital were also less likely to start on a racecourse compared to controls (OR 036; CI 0.15-0.83, P = 0.008). The presence of multisystem disease was associated with a decreased likelihood of surviving to be discharged (OR 0.13; 95% CI 0.02-0.90; P = 0.005), but did not affect the likelihood that they would start in at least one race if discharged successfully (OR 0.45; 95% CI 0.04-2.81; P = 0.34) compared to the other foals with septic arthritis. Log-rank comparison of survival curves confirmed that foals discharged following treatment for septic arthritis took significantly longer to start in their first race compared to the sibling population (mean age of study group 1757 days, CI 1604-1909; mean age of sibling group 1273 days, CI 1197-1349; P = 0.0006).

CONCLUSIONS

The development of septic arthritis in a TB foal significantly reduces the likelihood that it will start on a racecourse when compared to controls.

POTENTIAL RELEVANCE

Accurate figures allowing a realistic assessment of the athletic future of a foal following treatment for septic arthritis are of significance for both owner and treating veterinarian.

Third eyelid resection as a treatment for suspected squamous cell carcinoma in 24 horses

Between October 2000 and January 2007, 24 horses were presented with suspected squamous cell carcinoma (SCC) of the third eyelid. The hospital's medical records were analysed retrospectively to gain data about the cases, and telephone follow-up was obtained from the owners and referring veterinary surgeons. The resected third eyelid was submitted for histological examination in 21 cases; in the other three cases the tissue was not submitted at the owners' request, for economic reasons. SCC was confirmed in 16 of these 21 cases, three cases were diagnosed histologically as lymphoid hyperplasia, one as a mast cell tumour and one as a sebaceous gland adenocarcinoma. Long-term follow up over a median period of 41 months revealed no recurrence of SCC or associated problems; six of the 16 confirmed SCC cases were euthanased for unrelated reasons during the follow-up period.

Costs and complications of equine castration: a UK practice-based study comparing 'standing nonsutured' and 'recumbent sutured' techniques

REASONS FOR PERFORMING STUDY

Clinicians are often asked to guide owners and trainers over the relative advantages and disadvantages of equine castration performed in either the standing horse with an open unsutured scrotal wound with healing by second intention, or a recumbent horse under general anaesthesia in aseptic conditions, with sutured scrotal skin allowing primary wound closure.

OBJECTIVES

To identify types and frequency of complications following the 2 differing approaches, and to compare the financial cost associated with each procedure, based on practice charges.

METHODS

Veterinary expenses of 217 horses castrated by a Newmarket equine veterinary practice over an 18-month period were analysed. Of these, Group 1 (n = 121) were castrated standing and nonsutured by one of 2 ambulatory clinicians and Group 2 (n = 96) castrated in recumbency, in aseptic equine hospital conditions.

RESULTS

Group 1 had a complication prevalence of 22% with no mortalities, and Group 2 a significantly lower complication prevalence of 6% (P = 0.001) with a mortality rate of 1%. The financial cost of Group 1, without complications, was approximately one-third of the cost of uncomplicated Group 2. However, the cost of Group 1 with complications increased to approximately two-thirds of the cost of an uncomplicated Group 2 castration.

CONCLUSIONS

Even though the complication prevalence for Group 1 castrations leaving an open scrotal wound was significantly higher than for a recumbent horse with a sutured scrotal wound in a hospital, the average cost of Group 1 was still less, even taking into account the additional follow-up costs associated with treating such complications.

POTENTIAL RELEVANCE

This report provides a benchmark for the outcome of 2 methods of castration based on a database obtained from particular circumstances within the practice involved. Further studies are required to corroborate and take into account future development in surgical and anaesthetic techniques.

Mechanistic and inhibition studies of chorismate-utilizing enzymes

The shikimate biosynthetic pathway is utilized in algae, higher plants, bacteria, fungi and apicomplexan parasites; it involves seven enzymatic steps in which phosphoenolpyruvate and erythrose 4-phosphate are converted into chorismate. In Escherichia coli, five chorismate-utilizing enzymes catalyse the synthesis of aromatic compounds such as L-phenylalanine, L-tyrosine, L-tryptophan, folate, ubiquinone and siderophores such as yersiniabactin and enterobactin. As mammals do not possess such a biosynthetic system, the enzymes involved in the pathway have aroused considerable interest as potential targets for the development of antimicrobial drugs and herbicides. As an initiative to investigate the mechanism of some of these enzymes, we showed that the antimicrobial effect of (6S)-6-fluoroshikimate is the result of irreversible inhibition of 4-amino-4-deoxychorismate synthase by 2-fluorochorismate. Based on this study, a catalytic mechanism for this enzyme was proposed, in which the residue Lys-274 is involved in the formation of a covalent intermediate. In another study, Yersinia enterocolitica Irp9, which is involved in the biosynthesis of the siderophore yersiniabactin, was for the first time biochemically characterized and shown to catalyse the formation of salicylate from chorismate via isochorismate as a reaction intermediate. A three-dimensional model for this enzyme was constructed that will guide the search for potent inhibitors of salicylate formation, and hence of bacterial iron uptake.

Heavy metals have different effects on mycelial morphology of Achlya bisexualis as determined by fractal geometry

The morphological response, as measured by changes to mycelial area, radial extension and border fractal dimension, of the oomycete Achlya bisexualis to Cu, Co, Hg, Zn and Cd at concentrations of between 0.05 and 3 mM is described. All of the metals decreased mycelial area and radial extension. Border fractal dimension increased in the presence of Cu, Co and Hg with individual hyphae extending out beyond the mycelial margin. In the presence of 3 mM Hg these hyphae displayed spiral growth. Zn and Cd had no effect on border fractal dimension. We suggest that all of the metals slow growth and that Cu, Co and Hg may also disrupt the relationship between tip growth and branching at the edge of the mycelium.

Understanding bacteriophage therapy as a density-dependent kinetic process

Studies of bacteriophage as therapeutic agents have had mixed and unpredictable outcomes. We argue that interpretation of these apparently paradoxical results requires appreciation of various density-dependent threshold effects. We use a mathematical model to delineate different categories of outcome, including therapy by simple inundation, by active biocontrol, and by delayed active biocontrol. Counter-intuitively, there are situations in which earlier inoculation can be less efficacious, and simultaneous inoculation with antibiotics can be detrimental. Predictions of therapeutic responses are made using formulae dependent on biologically meaningful parameters; experimental measurement of the parameters will be a prerequisite of application of the model to particular study systems. Such modelling can point to which aspects of phage biology might most fruitfully be engineered so as to enhance the viability of bacteriophage therapy.

Phage therapy: the peculiar kinetics of self-replicating pharmaceuticals

The specter of antibiotic-resistant bacteria has provoked renewed interest in the possible use of bacteriophages to control bacterial infections. We argue that clinical application of phage therapy has been held back by a failure to appreciate the extent to which the pharmacokinetics of self-replicating agents differ from those of normal drugs. For self-replicating pharmaceutical agents, treatment outcome depends critically on various density-dependent thresholds, often with apparently paradoxical consequences. An ability to predict these thresholds and associated critical time points is a necessity if phage therapy is to become clinically practicable.

The spatial dynamics of prion disease

An important component of the latency period of the transmissible spongiform encephalopathies (prion diseases) can be attributed to delays during the propagation of the infectious prion isoform, PrPSc, through peripheral nervous tissues. A growing body of data report that the host prion protein, PrPC, is required in both peripheral and central nervous tissues for susceptibility to infection. We introduce a mathematical model, which treats the PrPSc as a mobile infectious pathogen, and show how peripheral delays can be understood in terms of the intercellular dispersal properties of the PrPSc strain, its decay rate, and its efficiency at transforming the PrPC. It has been observed that when two pathogenic strains co-infect a host, the presence of the first inoculated strain can slow down, or stop completely, the spread of the second strain. This is thought to result from a reduced concentration of host protein available for conversion by the second strain. Our model can explain the mechanisms of such interstrain competition and the time-course of the increased delay. The model provides a link between those data suggesting a role for a continuous chain of PrP-expressing tissue linking peripheral sites to the brain, and data on prion strain competition.

The paradoxical dynamics of prion disease latency

A salient characteristic of the prion diseases--including Creutzfeldt-Jakob disease and bovine spongiform encephalopathy in cattle--is an extended asymptomatic incubation period followed by a rapid and often fatal clinical phase. We present a kinetic model of progression of infection based upon the existence of a bottleneck in the natural protein pathways within the cell. The model can reconcile the different time-scales of the pre-clinical and clinical phases, and is able to account for the dependency of the duration of the incubation period on several important governing factors, including the inoculum size, the phenotype of the host, and the phenotype of the pathogenic form of the prion protein. Our results suggest that saturation events--first of the rate of pathogenic transformation (an auto-catalysis ceiling), and subsequently of the bottleneck in the protein pathways--could be fundamental in determining the dynamics of infection.

The evolution of virus-induced apoptosis

Viruses from several different families are able to exploit their host's cell death programmes so as to maximize viral fitness. Consideration of the evolution of such strategies has lead to the suggestion that the virus should inhibit apoptosis, in order to prolong the life of the cell and thereby maximize the number of progeny virions. The host, on the other hand, should stimulate apoptosis thereby inhibiting viral growth and blocking viral spread. For example, the function of the latent membrane protein I (LMPI) of the Epstein-Barr virus and the bcl-2 homologue gene A179L of African swine fever virus is to inhibit apoptosis. However, in other cases it is the virus that stimulates cell death or the host that benefits from inhibiting apoptosis, such as in fatal alphavirus encephalitis. This has been explained by assuming that virus-induced apoptosis in non-regenerating cells would be detrimental to the host. We present a mathematical framework for understanding virus-induced apoptosis which accounts for these two opposite solutions to virus infection with respect to the mode of virus replication and the life cycle of the target cell.

The dynamics of hepatitis B virus infection

We consider a cellular model of infection by the hepatitis B virus and describe how it may be used to account for two important features of the disease, namely (i) the wide variety of manifestations of infection and the age dependence thereof, and (ii) the typically long delay before the development of virus-induced liver cancer (primary hepatocellular carcinoma). The model is based on the assumption that the liver is comprised of both immature and mature hepatocytes, with these two subpopulations of cells responding contrastingly upon infection by the virus.

A cellular model to explain the pathogenesis of infection by the hepatitis B virus

The natural history of infection by the hepatitis B virus (HBV) depends on many factors, including the age and immunological status of the patient, and can range from acute transient infection to subclinical chronic hepatitis. Persistent infection often leads to the development of primary hepatocellular carcinoma. We consider a cellular model of HBV infection based on the hypothesis that the liver contains two populations of cells with contrasting responses to the virus. Our findings show that the model can be used to account for the wide variety of clinical manifestations of infection and can explain the observed age dependence of the main different outcomes of the disease.

A comparison of laparoscopically assisted vaginal hysterectomy vs traditional total abdominal and vaginal hysterectomies

The objective of this work was to compare laparoscopically assisted vaginal hysterectomy to traditional total abdominal and vaginal hysterectomies in seven critical areas: anesthesia time, surgery time, hospital stay, operative blood loss, total analgesic use, time required to return to work, and total cost of each of these procedures. The first 25 unscreened, consecutive laparoscopically assisted vaginal hysterectomies performed by the senior author were compared with 25 randomly selected traditional total abdominal and 25 randomly selected vaginal hysterectomies performed by the senior author's professional corporation. Laparoscopically assisted vaginal hysterectomy compared favorably to abdominal and vaginal hysterectomy in three areas and was superior to both total abdominal hysterectomy and vaginal hysterectomy in the remaining four areas. Although the use of the endoscopic stapling device and laser made the laparoscopically assisted vaginal hysterectomy a more expensive procedure than traditional vaginal hysterectomy, the expense was not significant and was justified by the decreased surgery time. The results of this comparative study suggest that laparoscopically assisted vaginal hysterectomy is superior or comparable to total abdominal hysterectomy and vaginal hysterectomy, especially for patients who may not have been candidates for vaginal hysterectomy. This procedure has allowed the gynecologic endoscopic surgeon to convert abdominal to vaginal procedures. Laparoscopically assisted vaginal hysterectomy provides an overall cost savings to the patient, has a low complication rate, adapts well to the outpatient setting, causes less patient discomfort, and allows the patient to return rapidly to home and workplace.

Analysis of a cellular model to account for the natural history of infection by the hepatitis B virus and its role in the development of primary hepatocellular carcinoma

Infection with the hepatitis B virus (HBV) can have many different outcomes. Transient infection may result in acute hepatitis or may remain subclinical. Persistent infection may also be subclinical, or may involve chronic active hepatitis, and can finally lead to the development of primary hepatocellular carcinoma. A mathematical model is given to account for the many different outcomes of HBV pathogenesis. The model is based on the assumption that the liver contains two cell populations with differing abilities to support active HBV replication and/or viral integration into the genome. The model helps account for the relationship of the different clinical courses of HBV infection to the age when the disease is acquired, together with the state of the immune system of the patient.

The toxicity of intravenously used marihuana

While no unanimity of opinion exists regarding the risk to physical health from smoking marihuana, we have seen four cases that demonstrate clearly that intravenous usage is hazardous. The severity of the multisystemic involvement is dose-related. On initial examination, signs of most severe overdosage included fulminant gastroenteritis, hypoalbuminemia, toxic hepatitis confirmed by serial biopsy, acute renal failure, electrolyte disturbances, leukocytosis, anemia, and a relative thrombocytopenia. In three patients who shared a common needle, gingivostomatitis also developed.

A Dynamic Rubber-Cord Composite Adhesion and Fatigue Test

Dynamic adhesion and fatigue tests can be conducted on the Firestone Flexometer, where the hysteresis effect of the rubber compound can be brought to bear on the rubber-cord interface. Only minor modifications of equipment need to be made to run this test under a range of different conditions. Although the test is designed for single-station testing, several samples can be run at once, and test conditions can be adjusted to prevent cycle-life from becoming excessive. Rubber-steel cord composites have been studied under dynamic conditions, and indications are that other cord types and dips can also be evaluated with this method. Thus, the study of adhesion can be approached from a different point of view than that which is provided by current static and dynamic tests.

Alteration of Sidman avoidance baselines by CSS paired with avoidable or unavoidable shock

2 tones, paired either with avoidable or unavoidable shock, were assessed for relative aversiveness or fear-evoking properties by presentation during Sidman avoidance responding. Results obtained from 8 dogs indicated no significant difference in the increase in avoidance rates produced by either tone. The increase in rate change was related to the ratio of reinforced to unreinforced CS presentation during fear conditioning.