Multidisciplinary management of ornithine transcarbamylase (OTC) deficiency in pregnancy: essential to prevent hyperammonemic complications

Ornithine transcarbamylase (OTC) deficiency is the most common inborn error in the metabolism of the urea cycle with an incidence of 1 in 14,000 live births. Pregnancy can trigger potentially fatal hyperammonemic crises. We report a successful pregnancy in a 29-year-old primiparous patient with a known diagnosis of OTC deficiency since infancy. Hyperammonemic complications were avoided due to careful multidisciplinary management which included a detailed antenatal, intrapartum and postnatal plan. Management principles include avoidance of triggers, a low-protein diet and medications which promote the removal of nitrogen by alternative pathways. Triggers include metabolic stress such as febrile illness, particularly gastroenteritis, fasting and any protein loading. In our case the patient, in addition to a restricted protein intake, was prescribed sodium benzoate 4 g four times a day, sodium phenylbutyrate 2 g four times a day and arginine 500 mg four times a day to aid excretion of ammonia and reduce flux through the urea cycle.

The risks of red cell transfusion for hip fracture surgery in the elderly

BACKGROUND AND OBJECTIVES

The benefits and indications for blood transfusion among surgical patients are controversial. There is evidence which suggests that blood transfusion is associated with poor clinical outcomes and risks of infection, but there are few data in the elderly population.

MATERIALS AND METHODS

Data were collected on haemoglobin concentrations and transfusions in 919 patients undergoing hip fracture repair at a university hospital over a 2-year period. 28-day and 180-day mortality were specified as primary outcomes. A composite infection outcome (chest infections, urinary tract infections and wound infections) was the main secondary outcome. Preoperative, operative and/or postoperative transfusions were the main exposure variable. Regression analyses were used to explore the associations between transfusion and outcomes, adjusting for pre-defined preoperative variables.

RESULTS

300 patients (32·6%) were transfused at least once during their admission. There was no evidence of a significant difference in either 28-day survival or 180-day survival between transfused and non-transfused hip fracture patients. The transfused group had higher adjusted composite infection rate (HR, 1·91; 95% CI, 1·41-2·59, P < 0·001) and prolonged length of stay in hospital than the non-transfused group (HR, 1·15; 95% CI, 1·07, 1·23, P < 0·001). Anaemia at the time of admission, extra capsular fracture and using walking aids in an indoor setting were preoperative variables, which predicted the need for transfusion.

CONCLUSION

Among an elderly population with hip fracture, blood transfusion was not associated with changes in mortality, but was associated with an increased rate of postoperative infection. These data add to the wider literature about adverse clinical outcomes in patients receiving blood transfusions and emphasises the need for prospective trials to evaluate the role of transfusion in the elderly.

Role for protein kinase C in controlling Aplysia bag cell neuron excitability

Targeting signalling molecules to ion channels can expedite regulation and assure the proper transition of changes to excitability. In the bag cell neurons of Aplysia, single-channel studies of excised patches have revealed that protein kinase C (PKC) gates a non-selective cation channel through a close, physical association. This channel drives a prolonged afterdischarge and concomitant neuropeptide secretion to provoke reproductive behaviour. However, it is not clear if PKC alters cation channel function and/or the membrane potential at the whole-cell level. Afterdischarge-like depolarizations can be evoked in cultured bag cell neurons by bath-application of Conus textile venom (CtVm), which triggers the cation channel through an apparent intracellular pathway. The present study shows that the CtVm-induced depolarization was reduced by nearly 50% compared to control following dialysis with the G-protein blocker, guanosine-5'-O-2-thiodiphosphate (GDP-β-S), or treatment with either the phospholipase C inhibitor, 1-[6-[[(17β)-3-Methoxyestra-1,3,5(10)-trien-17-yl]amino]hexyl]-1H-pyrrole-2,5-dione (U-73122), or the PKC inhibitor, sphinganine. Neurons exposed to the PKC activator, phorbol 12-myristate 13-acetate (PMA), displayed depolarization with accompanying spiking, and were found to be far more responsive to depolarizing current injection versus control. Immunocytochemical staining for the two typical Aplysia PKC isoforms, Apl I and Apl II, revealed that both kinases were present in unstimulated cultured bag cell neurons. However, in CtVm-treated neurons, the staining intensity for PKC Apl I increased, peaking at 10 min post-application. Conversely, the intensity of PKC Apl II staining decreased over the duration of CtVm exposure. Our results suggest that the CtVm-induced depolarization involves PKC activation, and is consistent with prior work showing PKC closely-associating with the cation channel to produce the depolarization necessary for the afterdischarge and species propagation.

125. ELEVATED FSH INCREASES PRIMORDIAL FOLLICLE RESERVE WITHOUT INCREASING PRIMORDIAL FOLLICLE FORMATION OR DECREASING OOCYTE QUALITY

Declining ovarian follicle reserve and oocyte quality with age can dictate the mammalian female reproductive lifespan. Elevated circulating levels of follicle-stimulating hormone (FSH) coincides with reproductive ageing in women, and is predicted to accelerate the depletion of ovarian follicle reserve by increasing the recruitment of remaining follicles. Unexpectedly, we found that transgenic expression of human FSH (TgFSH) increased primordial follicle reserve in mature GnRH-deficient hypogonadal (hpg) female mice functionally lacking endogenous gonadotrophin secretion1. Advancing our finding of increased primordial reserve in TgFSH-hpg mice, we find that total primordial follicle numbers is significantly increased (60%) in mature 26 week old non-hpg TgFSH females compared to WT controls. Thus, the FSH-induced increase in primordial reserve is maintained despite increased ovulation rate2 in mature TgFSH females. Embryo transfer experiments showed that embryos derived from 26 week old TgFSH females developed normally in recipient WT females, indicating no significant reduction in the viability of oocytes or early embryos produced by TgFSH mice. In addition, equal primordial numbers in 5 day old TgFSH versus WT ovaries suggested that FSH-induced changes to ovarian reserve was not due to an increased initial primordial follicle pool. Initial analysis of postnatal gene expression (qPCR) found elevated expression of granulosa cell markers (Kit-L, inhibin β) in TgFSH-hpg vs non-Tg hpg ovaries, indicating FSH actions during early follicle development. Therefore, contrary to a classical view that preantral follicles are gonadotrophin-independent, we provide in vivo evidence demonstrating FSH-induced changes to early follicle populations, as well as elevated FSH activity increasing or maintaining primordial reserve without compromising oocyte quality. (1) Allan CM et al. J Endocrinol. 2006; 188(3): 549–57.(2) McTavish KJ et al. Endocrinology. 2007; 148(9): 4432–9.

An open label study of the effects of rituximab in neuromyelitis optica

Eight patients with worsening neuromyelitis optica were treated with rituximab to achieve B cell depletion. Treatment was well tolerated. Six of eight patients were relapse free and median attack rate declined from 2.6 attacks/patient/year to 0 attacks/patient/year (p = 0.0078). Seven of eight patients experienced substantial recovery of neurologic function over 1 year of average follow-up. The pretreatment median Expanded Disability Status Scale score was 7.5, and at follow-up examination was 5.5 (p = 0.013).

Does the type of flooring affect the risk of hip fracture?

BACKGROUND

The number of hip fractures occurring worldwide in 1990 was estimated at 1.7 million and is predicted to rise to 6.3 million by 2050. The vast majority occur as a result of simple falls and the impact of the femoral trochanter with the floor. Previous studies have addressed the problem from the patient's side of the impact. Little research has been carried out on the other surface involved in the impact, the floor. STUDY LOCATION: 34 residential care homes.

METHODS

(1) The mechanical properties of the floor were measured with force transducers. (2) The number and location of falls and fractures on the various floors were recorded prospectively for 2 years. The threshold for reporting falls in different care homes was assessed using a standardised set of scenarios.

RESULTS

A total of 6,641 falls and 222 fractures were recorded. Wooden carpeted floors were associated with the lowest number of fractures per 100 falls. The risk of fracture resulting from a fall was significantly lower compared to all other floor types (odds ratio 1.78, 95% CI 1.33-2.35). The mean impact force was significantly lower on wooden carpeted floors: 11.9 kN compared to the other floor types.

DISCUSSION

The possible implications of our findings are considerable. Residents of homes are typically frail and many have a propensity to falls. In designing safer environments for older people, the type of floor should be chosen to minimise the risk of fracture. This may result in a major reduction in fractures in the elderly.

Plasma adrenocorticotropin (ACTH) concentrations and clinical response in horses treated for equine Cushing's disease with cyproheptadine or pergolide

Plasma ACTH levels have been variable in horses with a positive clinical response for therapy for equine Cushing's Disease (ECD). Therefore, our purpose was to determine the value of monitoring plasma adrenocorticotropin (ACTH) levels during treatment of equine Cushing's disease (ECD) with either cyproheptadine (n = 32) or pergolide (n = 10). First, we validated the chemiluminescent ACTH assay (specificity, precision, accuracy, intra-assay and interassay variations) and tested methods of handling the whole blood from the time of collection to when the ACTH was assayed. The sensitivity and specificity of high plasma ACTH levels for detecting ECD was determined in a retrospective study on hospitalised horses (n = 68). Surveys were sent to veterinarians who submitted equine ACTH levels that were high initially and had at least 2 ACTH samples to determine the value of monitoring ACTH levels during therapy of ECD. The ACTH chemiluminescent assay was valid. The ACTH was stable when whole blood was collected and held in plastic tubes for 8 h before separating the plasma. The sensitivity and specificity of plasma ACTH levels for detecting ECD were 84% (n = 19,95% CI 60,97) and 78% (n = 49,95% CI 63,88), respectively. Treated horses generally showed a decrease in plasma ACTH. Plasma ACTH levels may be helpful when monitoring therapy of ECD, although improvement in clinical signs should be considered most important. There were no differences between cyproheptadine and pergolide in terms of improvements in any of the clinical signs.

Screening for chlamydia in general practice

OBJECTIVE

To determine the prevalence of genital Chlamydia trachomatis infection in young patients presenting to general practitioners and to evaluate selective screening, based on risk factors, including gender.

METHODS

A cross sectional survey of 508 consecutive patients aged 18-24, presenting to six general practices and one youth clinic in Mackay, North Queensland. We screened urine for chlamydia using Ligase chain reaction.

RESULTS

Of 508 samples, 25 were positive (5%). The only factors with increased risks of infection were attendance at a youth clinic and recent change in sexual partner. It was as high in men as in women.

CONCLUSION

Prevalence of chlamydia infection may be high enough to support screening of all patients aged 18-24, depending on cost effectiveness studies.

Mild-to-moderate uncomplicated hypertension: further analysis of a cost-effectiveness study of five drugs

A cost-effectiveness model was designed to explore the effect of adding a new angiotensin-II inhibitor, telmisartan, to the therapeutic options for treating mild-to-moderate uncomplicated hypertension. Incorporating the cost of drugs, physician visits, and adverse-event treatments, the model concluded that availability of telmisartan on formulary may shorten the mean time and costs to control. The stability of the initial findings over a range of sensitivity analyses lends credence to the model conclusions that availability of telmisartan on formulary improves the therapeutic options of care for hypertension.

The small heat shock-related protein-20 is an actin-associated protein

PURPOSE

The activation of cyclic nucleotide-dependent signaling pathways in vascular smooth muscle is important for the prevention of vein graft spasm and neointimal hyperplasia. Cyclic nucleotide-dependent relaxation is associated with an increase in the phosphorylation of a small heat shock-related protein (HSP20). In this investigation, we examined the mechanisms by which HSP20 may modulate relaxation.

METHODS

The relaxation responses of the bovine carotid artery smooth muscles were determined in a muscle bath. HSP20 phosphorylation was quantitated with isoelectric-focusing immunoblots. The association with actin was determined with coimmunoprecipitation and cosedimentation. Molecular sieving columns were used to examine the macromolecular associations of HSP20.

RESULTS

The activation of cyclic nucleotide signaling pathways leads to the complete relaxation of carotid smooth muscle. This relaxation response is associated with an increase in the phosphorylation of HSP20. Actin coimmunoprecipitated with HSP20, and the association of actin with recombinant HSP20 in vitro was phosphorylation-state dependent. Finally, HSP20 exists in large (>100 kDa) aggregates, which dissociate with the activation of cyclic nucleotide signaling pathways.

CONCLUSION

These data support a role of HSP20 phosphorylation in mediating smooth muscle relaxation, possibly via a direct interaction of large aggregates of HSP20 with the contractile elements.

Heat shock protein expression in umbilical artery smooth muscle

Postpartum vasospasm in the umbilical arteries may be due to impaired vasorelaxation secondary to alterations in the expression of heat shock proteins. The contractile responses of pre- and full-term bovine umbilical artery smooth muscles were determined in a muscle bath. Heat shock protein expression was determined in bovine and human arterial tissues using western blotting with specific antisera. Full-term bovine and human umbilical artery smooth muscle was refractory to relaxation induced by the nitric oxide donor, sodium nitroprusside. This impaired vasorelaxation was associated with the expression of the inducible form of the heat shock protein, HSP70i, and increases in the expression of the small heat shock protein, HSP27. Small heat shock proteins have been implicated in modulating contraction and relaxation responses in vascular smooth muscles. Thus, alterations in heat shock protein expression may play a role in umbilical artery vasospasm.

Small heat shock proteins and vasospasm in human umbilical artery smooth muscle

Human umbilical artery smooth muscle is uniquely refractory to cyclic nucleotide-dependent vasorelaxation. Small heat shock proteins (HSPs) have been implicated as contractile regulatory proteins. Thus, we hypothesized that alterations in the phosphorylation of small HSPs may contribute to human umbilical artery smooth muscle vasospasm. Physiologic contractile responses were determined in a muscle bath and compared with phosphorylation events determined with whole-cell phosphorylation and 2-dimensional gel electrophoresis. Precontraction of bovine carotid artery smooth muscle with serotonin followed by relaxation with forskolin was associated with increases in the phosphorylation of HSP27 and HSP20. Precontraction of umbilical artery with serotonin followed by forskolin treatment led to increases in the phosphorylation of HSP27. However, the umbilical artery smooth muscle did not relax, nor was there an increase in the phosphorylation of HSP20 with forskolin treatment. These data suggest that impaired cyclic nucleotide-dependent relaxation of umbilical artery smooth muscle is associated with a lack of phosphorylation of HSP20.

Cellular mechanisms of cyclic nucleotide-induced vasorelaxation

PURPOSE

Endothelial-derived vasorelaxants such as prostacyclin and nitric oxide (NO) induce vascular smooth muscle relaxation through activation of cyclic nucleotide-dependent cellular signalling pathways. However, the specific events that lead to dissociation of actin and myosin and relaxation are not known. The purpose of this investigation was to determine the late phase signaling events that modulate vascular smooth muscle relaxation.

METHODS

Fresh bovine carotid artery smooth muscle (BCASM) contractile responses were determined in a muscle bath under Ca(2+)-containing and Ca(2+)-free conditions. Physiologic responses were correlated with phosphorylation events using whole cell phosphorylation and two-dimensional gel electrophoresis.

RESULTS

Cyclic nucleotide-dependent vasorelaxation can occur without detectable changes in intracellular Ca2+ concentrations. However, vascular smooth muscles that had been precontracted with the phosphatase inhibitor calyculin were refractory to relaxation. Vascular smooth muscle relaxation was associated with an increase in the phosphorylation of two 20 kDa proteins under Ca(2+)-containing and Ca(2+)-free conditions.

CONCLUSIONS

These results suggest that Ca(2+)-independent mechanisms may also modulate vascular smooth muscle relaxation. Two possible late phase signaling mechanisms include phosphatase activation and an increase in the phosphorylation of two 20 kDa phosphoproteins.

Nitric oxide is an autocrine feedback inhibitor of vascular smooth muscle contraction

BACKGROUND

Substances that increase intracellular calcium ([Ca2+]i), such as potassium chloride and serotonin, are known to induce vascular smooth muscle (VSM) contraction. One form of nitric oxide synthase, which converts L-arginine to nitric oxide, exists as a Ca(2+)-calmodulin dependent enzyme. The objective of this study was to determine whether agonists that induce VSM contraction by increasing [Ca2+]i might also activate Ca(2+)-calmodulin dependent nitric oxide synthase in VSM.

METHODS

Strips of bovine carotid arterial smooth muscle denuded of endothelium were equilibrated in a physiologic muscle bath. A maximal contractile response to high extracellular potassium chloride and serotonin was established. The strips were then preincubated with NG-monomethyl-L-arginine (L-NMMA), a structural analog of L-arginine and specific inhibitor of nitric oxide synthase, and again treated with either KCl or 5-hydroxytryptamine.

RESULTS

The contractile responses of muscle strips to KCl or 5-hydroxytryptamine were significantly greater in muscle strips pretreated with L-NMMA than responses in the absence of L-NMMA (p < 0.02, Student's t test). To determine whether this response was Ca2+ dependent, phorbolester-induced contractions in Ca(2+)-free conditions were examined. No difference was noted in the magnitude of Ca(2+)-free, phorbol ester-induced contractions in the presence and absence of L-NMMA.

CONCLUSIONS

These data thus suggest that Ca(2+)-calmodulin dependent nitric oxide synthase is functionally present in VSM and may function as an autocrine regulatory mechanism of VSM contraction.