Presynaptic Expression of LRIT3 Transsynaptically Organizes the Postsynaptic Glutamate Signaling Complex Containing TRPM1

Throughout the CNS, interactions between pre- and postsynaptic adhesion molecules establish normal synaptic structure and function. Leucine-rich repeat (LRR) domain-containing proteins are a large family that has a diversity of ligands, and their absence can cause disease. At the first retinal synapse, the absence of LRIT3 expression leads to the disassembly of the postsynaptic glutamate signaling complex (signalplex) expressed on depolarizing bipolar cell (DBC) dendrites. The prevalent view is that assembly of the signalplex results from direct postsynaptic protein:protein interactions. In contrast, we demonstrate that LRIT3 is expressed presynaptically, in rod photoreceptors (rods), and when we restore LRIT3 expression in Lrit3-/- rods, we restore expression of the postsynaptic glutamate signalplex and rod-driven vision. Our results demonstrate that, in the retina, the LRR-containing protein LRIT3 acts as a transsynaptic organizer of the postsynaptic complex required for normal synaptic function.

Oxidative and nitrative stress in neurodegeneration

Aerobes require oxygen for metabolism and normal free radical formation. As a result, maintaining the redox homeostasis is essential for brain cell survival due to their high metabolic energy requirement to sustain electrochemical gradients, neurotransmitter release, and membrane lipid stability. Further, brain antioxidant levels are limited compared to other organs and less able to compensate for reactive oxygen and nitrogen species (ROS/RNS) generation which contribute oxidative/nitrative stress (OS/NS). Antioxidant treatments such as vitamin E, minocycline, and resveratrol mediate neuroprotection by prolonging the incidence of or reversing OS and NS conditions. Redox imbalance occurs when the antioxidant capacity is overwhelmed, consequently leading to activation of alternate pathways that remain quiescent under normal conditions. If OS/NS fails to lead to adaptation, tissue damage and injury ensue, resulting in cell death and/or disease. The progression of OS/NS-mediated neurodegeneration along with contributions from microglial activation, dopamine metabolism, and diabetes comprise a detailed interconnected pathway. This review proposes a significant role for OS/NS and more specifically, lipid peroxidation (LPO) and other lipid modifications, by triggering microglial activation to elicit a neuroinflammatory state potentiated by diabetes or abnormal dopamine metabolism. Subsequently, sustained stress in the neuroinflammatory state overwhelms cellular defenses and prompts neurotoxicity resulting in the onset or amplification of brain damage.

Increased prevalence of Listeria monocytogenes in the faeces of patients receiving long-term H2-antagonists

BACKGROUND

Human listeriosis is an uncommon infection caused by the Gram-positive organism Listeria monocytogenes.

OBJECTIVE

To investigate the effects of therapeutic gastric acid suppression on faecal isolation of L. monocytogenes and the incidence of human listeriosis.

METHODS

Five stool specimens from each of 20 patients on continuous H2-antagonist therapy and two faecal samples from each of 47 healthy controls were investigated for the presence of Listeria spp.

RESULTS

A higher faecal isolation rate of L. monocytogenes was detected amongst the patients (20%) compared with the controls (2.1%) (P < 0.025). All subjects with stools positive for Listeria spp. were female, this sex difference being significant in the patient group (P < 0.0036) compared with controls. No patient, however, developed listeriosis.

CONCLUSION

Patients on long-term gastric acid suppressive therapy may be at increased risk of faecal carriage of L. monocytogenes.

Cap polyposis--an unusual cause of diarrhoea

'Cap polyposis' is a poorly recognised condition with distinct clinical, sigmoidoscopic, and pathological features that may be confused with other inflammatory conditions of the large intestine including pseudomembranous colitis and idiopathic chronic inflammatory bowel disease. The pathogenesis is unknown but on the basis of the characteristic histological appearances, which are similar to those seen in situations where mucosal prolapse is the underlying mechanism, it has been suggested that the latter may be an important aetiological factor. Two cases are described. Histological features in the first (presence of intramucosal elastin) and clinical features in the second (rectal prolapse) support the above hypothesis.

Late recurrence of surgically removed prolactinomas

The authors observed the clinical course of 24 women with surgically removed prolactinomas for a mean postoperative interval of 62 months. The frequency of late tumor recurrence and probable factors responsible for the recurrence were investigated. Hyperprolactinemia recurred in 4 of 13 patients with microadenomas (31%) 3 to 9 months after removal. In the macroadenoma group, relapse of hyperprolactinemia occurred in 10 of 11 patients (91%), an average of 26 months after the initial postoperative return to normal prolactin levels. Return of hyperprolactinemia was accompanied by radiologic evidence of tumor recurrence in all patients with macroadenoma, and in one patient with microadenoma. Of 12 tumors in which adjacent dura was available for histopathologic examination, 7 showed dural invasion. Although these seven patients had significantly higher preoperative levels of serum prolactin than the five without dural invasion, there was no significant relation between dural involvement and tumor recurrence. The probabilities of tumor recurring from multifocal adenoma or paraadenomatous lactotrope hyperplasia could not be assessed using our surgical material. The most plausible reason for the high recurrence rate of prolactinomas after apparent surgical cure, in the absence of defined anatomic abnormalities within the pituitary, is a functional abnormality of hypothalamic-pituitary control resulting from a primary hypothalamic disorder.

Intrathecal morphine for pelvic and sacral pain caused by cancer

Ten patients underwent placement of a lumbar subarachnoid catheter attached to a subcutaneous reservoir allowing daily injection of intrathecal morphine sulfate by family members. Sacral and pelvic pain were fairly well controlled. Neck and leg pain and pain mediated by the celiac plexus were not as well controlled by the intrathecal injection of morphine. The only significant complication was collection of cerebrospinal fluid around three reservoirs. Using this technique, narcotic concentration and frequency of administration can be easily altered to provide a safe but effective dose. Lumbar administration appears to block pain from lumbar and sacral dermatomes without the sedating and mood-altering effects of systemic narcotics.

CAT Scans: What Do They Tell Us?

The CAT Scan is capable of providing a diagnosis in many cases. It has an overall accuracy rate of 95 to 98 percent for diagnosis of a lesion versus no lesion. The CAT scanner has proven to be the single most important advance in neuroradiology in recent years. It is the least traumatic, the safest, and most definitive of the neurological procedures.

Percutaneous transluminal carotid angioplasty in fibromuscular dysplasia. Case report

A patient with fibromuscular dysplasia (FMD) of the internal carotid artery was treated by balloon percutaneous transluminal angioplasty (PTA). This is the sixth reported case of FMD stenotic disease which was dilated by PTA. All previous cases including the current example were treated successfully with resolution of symptoms. This procedure is associated with a relatively low morbidity and is an alternative method of treatment to operative endarterectomy for this disorder.

Quantitative analysis of lesion parameters in radiofrequency trigeminal rhizotomy

A series of 144 lesions made during 32 radiofrequency rhizotomies was reviewed. The parameters of each lesion were compared with the sensory change resulting from the lesion. One-half of the lesions resulted in no sensory change, but 16.7% produced numbness in a division not predicted by stimulation. This was a barely detectable sensory change in 6% of lesions and more dense in 10%. The first lesion in a series was particularly likely to result in sensory deficit, and accounted for half of the more dense lesions not predicted by stimulation. When the threshold at which stimulation was perceived was 0.2 volts or less, a lesion was likely to produce numbness, and when it was 0.5 volts or greater, marked sensory loss did not occur. There was no apparent relationship between the likelihood of sensory change and lesion temperature or duration. Analysis of lesion temperature was made more difficult by the use of low temperatures when numbness should be easy to obtain. With careful technique, radiofrequency rhizotomy can be performed with acceptable risk of unpredicted sensory loss. Particular care should be taken during the first lesion in each procedure and when stimulation thresholds are 0.2 volts or less.

Corneal sensitivity after percutaneous radiofrequency trigeminal rhizotomy: a quantitative study

Using the Cochet-Bonnet esthesiometer, we evaluated the corneal sensation in 13 patients with trigeminal neuralgia. We compared the preoperative and postoperative results after the trigeminal rhizotomy in a quantitative study. Of 13 patients who underwent operation, a decrease in corneal sensation developed compared with the eye that was not operated on in five patients. This decrease in sensitivity was not suggested by clinical symptoms or signs, and up to 23 months of follow-up failed to reveal any clinical symptoms. The failure to manifested clinical corneal symptoms in the follow-up period may result from the selective fiber destruction technique employed in radiofrequency rhizotomy with preservation of other myelinated nerves maintaining corneal nutrition.

Shock due to protamine hypersensitivity

A 56-year-old man developed shock and skin flush minutes after the slow administration of 25 mg of protamine sulfate. Prior protamine exposure from treatment of his diabetes with isophane insulin (NPH insulin) was believed to have sensitized this patient to protamine. A review of three other cases of reaction to low doses of protamine revealed that in each, the patient had previously been exposed to protamine. If heparin is used in a patient with a history of treatment of diabetes with isophane insulin, the heparin should be allowed to spontaneously reverse, without pharmacological assistance if possible. If protamine must be used, the patient should be pretreated with glucocorticoid and vasopressors should be immediately available.

Corneal anesthesia after percutaneous radiofrequency trigeminal rhizotomy. A retrospective study

Fifteen patients with intentional or unintentional V1 lesions one to five years after percutaneous radiofrequency trigeminal rhizotomy were examined. No corneal changes developed in the majority of patients. These findings raise the question as to the precipitating factor(s) for neuroparalytic keratitis. The suggested mechanism for preservation of corneal function appears to be intact axonal mechanism(s).

Cranial computed tomography in the diagnosis of symptomatic indirect trauma to the carotid artery

Five patients who were involved in motor vehicle accidents sustained indirect, nonpenetrating carotid artery injuries leading to cerebral infarction. Four patients were conscious when a severe lateralized neurological deficit developed three to 12 hours after injury indicating the presence of a vascular injury and not a mass lesion. In 3 patients with occlusion of the main stem middle cerebral artery, computed tomographic (CT) scans performed between 1 and 7 hours after the onset of the ischemic signs were normal, but all scans performed after 11 or more hours revealed progressive edema in a vascular distribution leading to a midline shift. The fifth patient had a severe diffuse brain injury and no apparent clinical pattern of a posttraumatic vascular complication. Sequential changes on the CT scans similar to those of the other patients led to the proper diagnosis of vascular injury; this was later confirmed by arteriography. Indirect, nonpenetrating injury to the carotid artery should be suspected in the presence of the typical clinical pattern or when serial CT scans show the evolution of progressive edema in a distribution atypical for traumatic contusion.

Cervical spine trauma: a cause of vertebral artery injury

Blunt injury to the neck can cause hemorrhage and pseudoaneurysm formation. A 76-year-old patient with severe blunt injury to the anterior neck was found to have entrapment of the left vertebral artery at C2-C3. Arch aortography 3 weeks postinjury revealed a large aneurysm at the injury site. The mass was surgically reduced, followed by ligation of the artery 9 days later, which resulted in prompt elimination of the mass and its accompanying bruit. Rapid recognition of this injury depends on early carotid and vertebral artery angiography.

Gigantism associated with a pituitary tumour secreting growth hormone and prolactin and cured by transsphenoidal hypophysectomy

An 18-year old male is reported who presented with a history of a growtn spurt over the year preceding his admission. His height was above the 97th percentile, and he had incompletely developed secondary sexual characters. Pituitary evaluation demonstrated a moderately elevated level of growth hormone (hGH) not suppressible by a glucose load and not stimulable by TRH or by L-DOPA. Serum prolactin (PRL) concentration was also increased while gonadotrophin, thyroid and adrenal function were all subnormal. There was clear radiological evidence of a large pituitary tumour with suprasellar extension and transsphenoidal total hypophysectomy was performed. A mixed chromophobe and acidophilic adenoma was found and both growth hormone and prolactin were demonstrable in different cells of the tumour by the immunoperoxidase technique. Post-operatively the patient has hypopituitarism and levels of growth hormone and prolactin have remained low or undetectable after 6 months. Thus early diagnosis and surgical treatment of gigantism of this mixed hGH-PRL secreting pituitary tumour was associated with a cure, which contrasts with the unfavourable outcome of many of the patients previously reported.

Delayed evolution of posttraumatic subdural hygroma

Five hundred and forty-six patients in a consecutive series of 1,601 patients with craniocerebral trauma had computed tomography. One hundred and ninety-six patients had a follow-up CT scan. Thirteen patients (6.6%) developed apparently "silent" subdural hygromas of delayed evolution noted from six to 46 days after injury (average 22 days). Three of 10 patients (30%) improved after operation. No patient with a severe cerebral deficit (decortication or decerebration) improved. The three unoperated hygromas and the six that persisted after operation tended to resolve spontaneously. The infrequent and modest improvement following surgical treatment and the tendency to spontaneous resolution suggest that operation may be unnecessary in many patients with posttraumatic subdural hygroma of delayed evolution.

Galactorrhoea and hypogonadism associated with a radiologically-inapparent prolactin-secreting pituitary tumour

A 38 year old man was investigated because of impotence, gynaecomastia and galactorrhoea. Hyperprolactinaemia and hypogonadism were documented. Pituitary function was otherwise normal as was tomographic examination of the sella turcica. In the absence of direct evidence of pituitary involvement (hyperprolactinaemia can suppress gonadal function) and to exclude ectopic prolactin production, venous blood was drawn at multiple sites. The highest prolactin levels were found in the superior vena cava and above, indicating an intracranial source. At transsphenoidal hypophysectomy a microadenoma was removed; tumour cells contained typical prolactin secretory granules on electron microscopy. In the light of this report the appropriateness of dividing hyperprolactinaemia into "tumourous" and "idiopathic" subgroups on the basis of sella size must be reconsidered. Functional tests do not distinguish between the subgroups although prolactin levels tend to be higher when the sella is enlarged. Only a quantitative rather than a qualitative difference may exist between the subgroups.

Indications for nonoperative treatment of spinal cord compression due to breast cancer

A retrospective series of 12,478 patients with breast cancer included 2467 patients with spinal metastases. Local treatment was not necessary in 688 patients. Neurological dificit did not develop in 1735 patients who underwent radiotherapy. Forty-four patients developed myelopathy due to spinal cord compression as demonstrated by neurological examination and myelography. Twenty-six of these patients were initially treated by laminectomy and 18 were initially treated with radiotherapy. The two groups did not significantly differ in their outcome with respect to motor power, pain relief, or ability to walk. Six patients who underwent radiotherapy deteriorated during 2 months of treatment. Four of these patients were not operative candidates because of poor general condition (three patients) or long duration of paraplegia (one patient). Of two patients who underwent emergency laminectomy, one became paraplegic; however, the other patient was significantly improved. For this reason it is essential that patients undergoing radiotherapy for spinal cord compression be followed closely by a neurosurgeon. The authors believe that in appropriate cases radiotherapy alone can yield results as good as laminectomy combined with radiotherapy.

External carotid-vertebral artery anastomosis for vertebrobasilar insufficiency

Two patients with previous brain stem infarction and current symptoms of vascular insufficiency in the basilar circulation had evidence of vertebral artery occlusive disease. Angiography demonstrated ostial stenosis of the dominant right vertebral artery and retrograde flow down the left vertebral artery to the level of the transverse process of C2 in the first case and to the level of a severely stenosed origin in the second case. Carotid circulation was patent in both cases. The blood flow in the posterior circulation was patent in both cases. The blood flow in the posterior circulation was augumented by extracranial anastomosis of the external carotid artery to the vertebral artery in the foramen transversarium at the level of C1-2 by a lateral approach in Case 1 and at the level of C4-5 by an anterior approach in Case 2. Postoperative improvement in neurologic status occurred in both cases.

A semiautomated micromethod for dextran in the presence of glucose

A semiautomated method for microanalysis of dextran with anthrone reagent has been developed. The method utilizes the Technicon inulin manifold and other standard AutoAnalyzer equipment. Since the anthrone method is sensitive to plasma glucose, a glocuse oxidase method which eliminates glucose in samples to be analyzed for dextran has also been developed. When solutions containing 50 mg. per 100 ml. of dextran were compared to solutions containing 50 mg. per 100 ml. of dextran plus up to 200 mg. per 100 ml. glucose, no significant difference was observed. The coefficient of the anthrone-glucose oxidase method is 0.039, which is within the error of the AutoAnalyzer itself.

Ganglion of the peroneal nerve. Report of two cases

✓ Peroneal nerve ganglion masquerades as other lesions and may not be diagnosed except at operation; it can be treated by surgery. Two cases are reported and the literature summarized.