Characterization of the binding of [3H]-SB-204269, a radiolabelled form of the new anticonvulsant SB-204269, to a novel binding site in rat brain membranes

1. SB-204269 (trans-(+)-6-acetyl-4S-(4-fluorobenzoylamino)-3,4-dihydro-2,2-dimethyl-2H-benzol[b]pyran-3R-ol, hemihydrate) shows potent anticonvulsant activity in a range of animal seizure models, with a lack of neurological or cardiovascular side-effects. The profile of the compound suggests that it may have a novel mechanism of action. This study describes the characteristics of a binding site for [³H]-SB-204269 in rat forebrain membranes.
2. Specific [³H]-SB-204269 binding was saturable and analysis indicated binding to a homogenoeous population of non-interacting binding sites with a dissociation constant (K_D) of 32±1 nM and a maximum binding capacity (B_max) of 253±18 fmol mg⁻¹ protein. Kinetic studies indicated monophasic association and dissociation. Binding was similar in HEPES or Tris-HCl buffers and was unaffected by Na⁺, K⁺, Ca²⁺ or Mg²⁺ ions. Specific binding was widely distributed in brain, but was minimal in a range of peripheral tissues.
3. Specific [³H]-SB-204269 binding was highly stereoselective, with a 1000 fold difference between the affinities of SB-204269 and its enantiomer SB-204268 for the binding site. The affinities of analogues of SB-204269 for binding can be related to their activities in the mouse maximal electroshock seizure threshold (MEST) test of anticonvulsant action.
4. None of the standard anticonvulsant drugs, phenobarbitone, phenytoin, sodium valproate, carbamazepine, diazepam and ethosuximide, or the newer anticonvulsants, lamotrigine, vigabatrin, gabapentin and levetiracetam, showed any affinity for the [³H]-SB-204269 binding site. A wide range of drugs active at amino acid receptors, Na⁺ or K⁺ channels or various other receptors did not demonstrate any affinity for the binding site.
5. These studies indicate that SB-204269 possesses a specific CNS binding site which may mediate its anticonvulsant activity. This binding site does not appear to be directly related to the sites of action of other known anticonvulsant agents, but may have an important role in regulating neuronal excitability.

     

Protecting privacy during video recording resuscitations

The practice of video recording resuscitations is reviewed with respect to the following issues:

• ? the protection of patients' rights to privacy during and after recordings
• ? the non status of recordings as a medical record
• ? the need for staff acceptance and institutional approval prior to beginning recordings
• ? the use of recordings for quality improvement audit, critical incident monitoring, instructional feedback and resuscitation review conferences
• ? the recommendation that recordings are then erased, and
• ? the utility of legislative protection to facilitate the process of quality improvement.

     

Testicular Trauma: Potential Impact on Reproductive Function

Purpose

The long-term effects of testicular trauma on reproductive function are unknown. In an effort to define the relationship between testicular injury and fertility in humans, we identified patients with a history of testicular trauma and assessed parameters commonly associated with fertility.

Materials and Methods

We reviewed 15 patients 23 to 59 years old who underwent immediate exploration after testicular trauma between 1972 and 1991. Of the patients 11 were contacted and 8 returned for prospective followup. Reproductive and sexual histories, physical examination, measurements of serum hormones and antisperm antibodies, semen analysis and scrotal ultrasound were done.

Results

Of the 8 patients 1 (13 percent) achieved and 7 (87 percent) did not attempt conception. Hormonal status was normal in all 8 patients. Six men had objective evidence of subfertility by semen analysis only, although none had severe oligospermia or asthenospermia and only 1 had severe teratospermia. Five of 9 traumatized testes were atrophic. Interestingly, only 1 patient had antisperm antibodies, the levels of which were probably low enough to be clinically insignificant.

Conclusions

There was definite evidence of subfertility as assessed by abnormal semen analyses and atrophic testes following testicular trauma. However, the subfertility did not appear to be immune mediated nor did the patients present with infertility. Since only 1 patient had severely compromised fertility according to semen analysis we conclude that early repair can help preserve hormonal function as well as fertility.     

Anaesthetic management of acute blunt thoracic trauma

Sunnybrook Health Science Centre is an adult regional trauma unit serving metropolitan Toronto and environs. We undertook a nvo-year retrospective review of patients admitted to our institution with blunt thoracic trauma. Three hundred and thirty-three patients with blunt trauma and an injury severity score (ISS) greater than 17 required emergency surgery. Of these, 208 had blunt thoracic injuries while 125 did not have chest injuries. Both groups were similar with respect to age but patients with thoracic trauma had a greater ISS. (P < 0.05) and greater intraoperative mortality (P < 0.01). The aetiology of the intraoperative deaths with one exception was exsanguination. Emergency thoracotomy or sternotomy indicated a poor prognosis with a mortality rate of 80%. The most common intraoperative problem was an elevated airway pressure. Awake intubation was undertaken in 77.5% of patients requiring anaesthesia and surgery because of the potentially compromised airways and difficult intubations due to the nature of the associated injuries. Finally, 74% of patients undergoing urgent surgery required mechanical postoperative ventilation. The presence of blunt chest trauma should be considered a marker of the severity of injury sustained by the patient.     

Oral and written story composition skills of children with language impairment.

In this study 538 children composed 1 oral and 1 written fictional story in both 2nd and 4th grades. Each child represented 1 of 4 diagnostic groups: typical language (TL), specific language impairment (SLI), nonspecific language impairment (NLI), or low nonverbal IQ (LNIQ). The stories of the TL group had more different words, more grammatical complexity, fewer errors, and more overall quality than either language-impaired group at either grade. Stories of the SLI and LNIQ groups were consistently stronger than were those of the NLI group. Kindergarten children with language impairment (LI) whose standardized test performance suggested normalization by 2nd grade also appeared to have recovered in storytelling abilities at that point. By 4th grade, however, these children's stories were less like the children with TL and more like those of children with persistent LI than they had been in 2nd grade. Oral stories were better than written stories in both grades, although the greatest gains from 2nd to 4th grade were generally made on written stories. Girls told stronger stories than did boys at both grades, regardless of group placement. It is concluded that story composition tasks are educationally relevant and should play a significant role in the evaluation of children with developmental LI.     

Asymptomatic spondylodiscitis an unusual feature of ankylosing spondylitis

Six patients with ankylosing spondylitis were found to have asymptomatic spondylodiscitis. They have been followed for a mean of 17 years and have been free of symptoms or complications from this lesion. This benign asymptomatic course has not been stressed by previous authors.     

General anesthetics selectively modulate glutamatergic and dopaminergic signaling via site-specific phosphorylation in vivo

Isoflurane, propofol and ketamine are representative general anesthetics with distinct molecular mechanisms of action that have neuroprotective properties in models of excitotoxic ischemic damage. We characterized the effects of these agents on neuronal glutamate and dopamine signaling by profiling drug-induced changes in brain intracellular protein phosphorylation in vivo to test the hypothesis that they affect common downstream effectors. Anesthetic-treated and control mice were killed instantly by focused microwave irradiation, frontal cortex and striatum were removed, and the phosphorylation profile of specific neuronal signaling proteins was analyzed by immunoblotting with a panel of phospho-specific antibodies. At anesthetic doses that produced loss of righting reflex, isoflurane, propofol, and ketamine all reduced phosphorylation of the activating residue T183 of ERK2 (but not of ERK1); S897 of the NR1 NMDA receptor subunit; and S831 (but not S845) of the GluR1 AMPA receptor subunit in cerebral cortex. At sub-anesthetic doses, these drugs only reduced phosphorylation of ERK2. Isoflurane and ketamine also reduced phosphorylation of spinophilin at S94, but oppositely regulated phosphorylation of presynaptic (tyrosine hydroxylase) and postsynaptic (DARPP-32) markers of dopaminergic neurotransmission in striatum. These data reveal both shared and agent-specific actions of CNS depressant drugs on critical intracellular protein phosphorylation signaling pathways that integrate multiple second messenger systems. Reduced phosphorylation of ionotropic glutamate receptors by all three anesthetics indicates depression of normal glutamatergic synaptic transmission and reduced potential excitotoxicity. This novel approach indicates a role for phosphorylation-mediated down-regulation of glutamatergic synaptic transmission by general anesthetics and identifies specific in vivo targets for focused evaluation of anesthetic mechanisms.     

The value of two-step operative laparoscopy with interval pituitary suppression in the treatment of infertility caused by severe endometriosis

PURPOSE OF REVIEW: To appraise a new approach to laparoscopic surgery for infertility caused by advanced endometriosis. RECENT FINDINGS: Endometriosis is a common systemic and local disease with altered peritoneal function, which requires both systemic and local treatment. Medication alone cannot improve infertility, and laparoscopic treatment, particularly in severe endometriosis, has a high recurrence rate and is often limited by technical difficulties. Novel treatment strategies have therefore to be sought, especially in women who do not want in-vitro fertilization as a first option, either because they suffer from pain in addition to infertility or want to enhance their fertility over many cycles. SUMMARY: Two-step operative laparoscopy with interval pituitary suppression by means of gonadotrophin-releasing hormone analogues reduces the extent of endometriosis, as classified by the American Fertility Association, and appears to be a promising method of achieving optimal cytoreduction and facilitating complicated surgery in severe endometriosis, while protecting the ovary from unnecessary trauma. A large-scale well-designed study is needed to confirm that this treatment leads to improved pregnancy rates.