Delayed multidose treatment with nicotinamide extends the degree and duration of neuroprotection by reducing infarction and improving behavioral scores up to two weeks following transient focal cerebral ischemia in Wistar rats

A single, delayed dose of nicotinamide (NAm) was shown to be protective against focal cerebral ischemia in rats, but the protection was limited to three to seven days following stroke. The investigation reported here was conducted to examine if the use of multiple doses of NAm, administered after the onset of focal cerebral ischemia, would extend the duration of neuroprotection compared with a single dose treatment regimen. Male Wistar rats were subjected to transient focal cerebral ischemia by occluding the right middle cerebral artery (MCAo) for two hours. Following MCAo, motor and sensory behavioral tests were performed daily and the cerebral infarct volumes were measured at two weeks after sacrifice. Each animal was placed into one of four groups that received either normal saline alone (Group S), one (Group A), two (Group B), or three (Group C) doses of NAm (500 mg/kg). Each animal, therefore, received three treatments over two weeks, with the first dose administered intravenously two hours after the onset of MCAo. Single and multiple doses of NAm reduced the infarction (p < 0.01) and improved (p < 0.05) the neurologic sensory and motor behavior when compared with the saline-treated animals up to two weeks after stroke. Moreover, animals that received multiple doses of NAm recuperated full motor function not different from normal, preoperative motor behavior. Delayed treatment with NAm given as multiple doses, therefore, further enhances the extent and duration of neuroprotection by significantly reducing cerebral infarct volumes, improving neurologic behavioral scores, and confers a complete motor recovery up to two weeks from the onset of focal cerebral ischemia in Wistar rats.

Endoscope-assisted microsurgery for treatment of a suprasellar craniopharyngioma presenting precocious puberty

Being the most common childhood tumor to involve the hypothalamus and pituitary gland, craniopharyngioma, a histologically benign tumor, is usually related to growth retardation and hypogonadism. The presentation of precocious puberty is very rare for a hypothalamic craniopharyngioma. Here, we report such a case. The female patient had presented with symptoms of menarche and breast development since she was 6 years old. Hormonal therapy with a gonadotropin-releasing hormone analogue was instituted to cease precocious puberty but was unsuccessful. Magnetic resonance imaging of the sella showed a 1-cm tumor in the hypothalamic area. Through a pterional approach, the tumor was removed en bloc with endoscope-assisted microsurgery. After the operation, our patient's symptoms improved, so the hormone therapy was discontinued. This extremely unique association of craniopharyngioma and precocious puberty, the causes and mechanisms involved along with the advantages of endoscope-assisted microsurgery are discussed.

Harmonic leakage and image quality degradation in tissue harmonic imaging

Image quality degradation caused by harmonic leakage was studied for finite amplitude distortion-based harmonic imaging. Various sources of harmonic leakage, including transmit waveform, signal bandwidth, and system nonlinearity, were investigated using both simulations and hydrophone measurements. Effects of harmonic leakage in the presence of sound velocity inhomogeneities were also considered. Results indicated that sidelobe levels of the harmonic beam pattern were directly affected by harmonic leakage when the harmonic signal was obtained by filtering out the fundamental signal. Because sidelobe levels also increase with the bandwidth of the transmitted signal, a trade-off exists between axial resolution and contrast resolution. It is concluded that accurate control of the frequency content of the waveform prior to propagation is necessary to optimize imaging performance of tissue harmonic imaging. The filtering technique was also compared with the pulse inversion technique. It was shown that the pulse inversion technique effectively suppresses harmonic leakage at the cost of imaging frame rate and potential motion artifacts.

Cerebral intraventricular hemorrhage caused by a large cerebral arteriovenous malformation at 31 years after diagnosis

Cerebral arteriovenous malformation (AVM) has an overall 2% to 4% annual risk of hemorrhage. The annual risk of hemorrhage does not decrease with age. However, the natural history of non-operative AVM is difficult to follow up consistently for more than 30 years. In this report, we present a case with a large cerebral AVM which developed a major bleeding causing intraventricular hemorrhage (IVH) 31 years after the diagnosis. A male patient was proved to have a cerebral AVM in the right corpus callosum by cerebral angiography at ages 20 and 28. He was found losing consciousness due to rupture of AVM with IVH at age 51. A small cerebral aneurysm and a dilated vein (aneurysm) of Galen were noted also. A craniotomy with removal of the hematoma and microsurgical resection of the AVM was performed immediately, and the patient regained normal respiration and consciousness about 2 months and 7 months after craniotomy, respectively. We recommend that neurosurgeons should play active roles in encouraging young patients with large AVMs to receive microsurgical resection.

Differential alteration of catecholamine release during chemical hypoxia is correlated with cell toxicity and is blocked by protein kinase C inhibitors in PC12 cells

Release of neurotransmitters, including dopamine and glutamate, has been implicated in hypoxia/ischemia-induced alterations in neuronal function and in subsequent tissue damage. Although extensive studies have been done on the mechanism underlying the changes in glutamate release, few have examined the mechanism that is responsible for the changes in catecholamines. Rat pheochromocytoma-12 (PC12) cells synthesize, store, and release catecholamines including DA and NE. Therefore, we used HPLC and ED to evaluate extracellular DA and NE concentrations in a medium during chemical hypoxia in PC12 cells. Chemical hypoxia produced by KCN induced differential release of DA and NE. Under normal glucose conditions, KCN induced release of NE, but not DA. Under glucose-free conditions, KCN-induced release of DA was elevated transiently, whereas the release of NE increased progressively. Under parallel conditions, KCN biphasically elevated the level of cytosolic free calcium ([CA(2+)](i)) in glucose-free DMEM, peaking at 95 +/- 18 nM at 1,107 +/- 151 s, followed by a new plateau level at 249 +/- 24 nM sustained from 4,243 +/- 466 to 5,263 +/- 440 s. Cell toxicity, as measured by LDH release, was increased significantly by KCN in glucose-free DMEM but was diminished in the presence of glucose, and was correlated with DA release by chemical hypoxia. The protein kinase C (PKC) inhibitor GO6976 or staurosporine inhibited KCN-induced LDH release as well as the release of NE and DA. Taken together, selective activation of DA but not NE was correlated with the LDH release by chemical hypoxia, and was diminished with GO6976 or staurosporine. These results suggest that selective activation of PKC isoforms is involved in the chemical hypoxia-induced DA release, which may lead to neuronal cell toxicity.

A novel agarofuran sesquiterpene, celahin D from Celastrus hindsii Benth

A novel agarofuran sesquiterpene polyol ester, 1beta,2beta,6alpha,15beta-tetracetoxy-8 beta,9alpha-dibenzoyloxy-beta- dihydroagarofuran (celahin D) (1), two known analogues of 1,1beta-acetoxy-8beta,9alpha-dibenzoyloxy-4al pha6alpha-dihydroxy-2beta(alphamethylbutanoyloxy)-beta-++ +dihydroagarofuran (2) and beta-acetoxy-8beta,9alpha-dibenzoyloxy-6alpha-hy droxy-2beta(alpha -methylbutanoyloxy)-beta-dihydroagarofuran (3), and a known cytotoxic sesquiterpene pyridine alkaloid, emarginatine E (4) were isolated from the stems of Celastrus hindsii Benth. Three known triterpenes, loranthol (5), lupenone (6) and friedelinol (7) were also obtained from the titled plant. Structural elucidation of compound 1 was established by 2D NMR spectra.

Endoscopic endonasal transsphenoidal surgery for pituitary tumors

BACKGROUND

The traditional transsphenoidal approach for pituitary surgery can be performed via transnasal, transseptal, or sublabial routes through unilateral or bilateral nostrils. It requires wide mucosal and septal dissection and postoperative nasal packing. Endoscopic surgery has been widely used because it allows excellent visualization with minimal invasion. Recently, it has also been applied to pituitary surgery.

METHODS

From January, 1997 to February, 1999, 40 patients with pituitary adenomas underwent the transsphenoidal approach using a rigid endoscope via one nostril. Among the 40 cases, 18 were prolactinomas, seven were growth hormone-secreting adenomas and 15 were nonfunctional adenomas.

RESULTS

After surgery, complete resolution or improvement of symptoms and restoration of normal hormone levels were achieved in 16 patients with prolactinomas, five with growth hormone-secreting adenomas and 12 with nonfunctional macroadenomas. One patient with a recurrent microprolactinoma needed a second operation to remove the cavernous portion of the tumor. Another male patient with a macroprolactinoma who experienced galactorrhea and gynecomastia showed improvement of clinical symptoms after the operation. Two patients with residual growth hormone-secreting macroadenomas in the cavernous sinus needed Sandostatin treatment. Three patients with nonfunctional macroadenomas underwent nearly total resection leaving residual tumor in the cavernous sinus, which then required adjuvant radiotherapy. No complications related to this approach were encountered in the patients during the follow-up period.

CONCLUSIONS

Endonasal transsphenoidal endoscopic surgery can be employed for treating pituitary tumors without septal or sublabial complications. Postoperative suffering was reduced and hospitalization was shortened by this mini-invasive procedure. This surgical procedure can be used for both microadenomas and macroadenomas.

Doppler angle estimation using correlation

Conventional Doppler techniques can only detect the axial component of blood flow. To obtain the transverse flow component, an approach based on the dependence of Doppler bandwidth on Doppler angle has been widely investigated. To compute the bandwidth, a full Doppler spectrum is often required. Therefore, this approach has not been applied to real-time, two-dimensional Doppler imaging because of the long data acquisition time. To overcome this problem, a correlation-based method is proposed. Specifically, variance of the Doppler spectrum is used to approximate the square of the Doppler bandwidth. Because variance is computed efficiently and routinely in correlation-based color Doppler imaging systems, implementation of this method is straightforward. In addition, the two-dimensional velocity vector can be calculated and mapped to different colors using the color mapping function of current systems. Simulations were performed, and experimental data were also collected using a string phantom with the Doppler angle varying from 23 degrees to 82 degrees . Results indicate that the correlation-based method may produce significant errors if only a limited number of flow samples are available. With averaging, however, the Doppler angles estimated by the correlation-based method can achieve good agreement with the true angles by using only four flow samples with proper variance averaging.

Effects of transmit focusing on finite amplitude distortion based second harmonic generation

Generation of the second harmonic signal was studied for finite amplitude distortion based harmonic imaging. Acoustic field amplitudes along the range axis of a fixed focus transducer were measured using a PVDF needle hydrophone. Results indicated that on-axis amplitudes strongly depended on the f-number at both the fundamental and the second harmonic frequencies. Differences of the on-axis amplitudes between the two frequencies were also investigated. To explore the possibility of increasing harmonic generation by extending the depth of focus, a two-focus transducer was employed. Hydrophone measurements, pulse-echo imaging and simulations were performed. Although the increase in harmonic generation depended on specific imaging parameters, the effectiveness of improving the harmonic signal-to-noise ratio (SNR) by increasing the depth of field was clearly demonstrated. Degradation in contrast resolution associated with the two-focus transducer was also evaluated. It was found that the contrast resolution was still significantly better than that of the fundamental image at the same frequency. Results of the study using the two-focus transducers can be generalized to imaging systems with full dynamic transmit focusing capabilities. In other words, it is expected that dynamic transmit focusing can improve the SNR of finite amplitude distortion based second harmonic imaging while improving the contrast resolution over fundamental imaging.

Antioxidant principles from Ephemerantha lonchophylla

One dihydrostilbene and three phenanthrene antioxidants were isolated from an ethanolic extract of the Chinese herbal Ephemerantha lonchophylla. One of these compounds, ephemeranthone (4) is a new natural product. Denbinobin (1) and 3-methylgigantol (3) have been previously isolated from this plant, and 3-ethoxy-5-hydroxy-7-methoxy-1,4-phenanthraquinone (2) is an artifact. The structures of these compounds were determined by spectroscopic analysis. The antioxidative activities for inhibiting human low density lipoprotein oxidation in vitro of compounds 1-4 were determined, and only 4 was active (5.3 times that of probucol).

Cytotoxicity of curcuminoids and some novel compounds from Curcuma zedoaria

Bioassay-directed fractionation of an EtOH extract of Curcuma zedoaria led to isolation of an active curcuminoid, which was identified as demethoxycurcumin (2) by comparison of its 1H and 13C NMR spectra with literature data and by direct comparison with synthetic material. Curcumin (1) and bisdemethoxycurcumin (3) were also obtained. Curcuminoids (1-3) were synthesized and demonstrated to be cytotoxic against human ovarian cancer OVCAR-3 cells. The observed CD50 values of 1, 2, and 3 were 4.4, 3.8, and 3.1 microg/mL, respectively. Three additional novel compounds, 3, 7-dimethylindan-5-carboxylic acid (4), curcolonol (5), and guaidiol (6), were also isolated from the EtOH extract. The structures and relative stereochemistry of 4-6 were determined by spectroscopic methods and X-ray crystallographic analysis.

Os odontoideum: a case report and review

There are five types of odontoid anomalies: os odontoideum, ossiculum terminale, hypoplasia of the odontoid, aplasia of the odontoid base and aplasia of the odontoid. All five anomalies may lead to atlantoaxial instability. Their clinical signs, symptoms and treatments are identical. Only radiographic findings are distinctive. The incidence of odontoid anomalies is uncertain. A 15-year-old boy was hospitalized with progressive numbness of his limbs on the right side for one month. Os odontoideum was confirmed by cervical radiography and magnetic resonance imaging. The lesion was stabilized with autogenous iliac bone fusion and Halifax interlaminar clamp fixation. Treatment with posterior fusion of the C1-C2 vertebrae proved successful. The clinical variations, etiology, diagnosis and surgical management of odontoid anomalies are discussed.

Glial cell-specific differences in response to alkylation damage

Oligodendrocytes are preferentially sensitive to the toxic, carcinogenic, and teratogenic effects of methylnitrosourea (MNU). The mechanisms responsible for this enhanced sensitivity have not been fully elucidated. One of the most vulnerable cellular targets for this chemical is mitochondrial DNA (mtDNA). To determine if differences in mtDNA damage and repair capacity exist among the different CNS glial cell types, the effects of MNU exposure on oligodendroglia, astroglia, and microglia cultured separately from neonatal rat brain were compared. Quantitative determinations of mtDNA initial break frequencies and repair efficiencies showed that whereas no cell type-specific differences in initial mtDNA damage were detected, mtDNA repair in oligodendrocytes, oligodendrocyte progenitors, and microglia was significantly reduced compared to that of astrocytes. In astrocytes, and all other cell types previously evaluated in our laboratory, >60% of N-methylpurines were removed from the mtDNA by 24 hr. In contrast, only 35% of lesions were removed from mtDNA of oligodendrocytes, oligodendrocyte progenitors, and microglia during the same time period. Mitochondrial perturbations by a variety of xenobiotics have been linked to apoptosis. In the present study, apoptosis, as determined by DNA laddering and ultrastructural analysis, was clearly induced by MNU treatment of cultured oligodendrocyte progenitors and microglia, but not in astroglia. These data demonstrate a correlation between diminished mtDNA repair capacity and the induction of apoptosis. However, further experimentation is necessary to determine if a causal relationship exists and contributes to the vulnerability of oligodendroglia following exposure to N-nitroso compounds in the environment or in chemotherapeutic regimen.

Microsurgical management of intracranial epidermoid cysts

BACKGROUND

Intracranial epidermoid cysts are slow-growing congenital neoplasms that usually spread and adhere to critical neurovascular structures along the basal cistern, particularly the cerebellopontine angle (CPA) and parasellar region. Clinical symptoms include trigeminal neuralgia, headache and dizziness, progressive hemiparesis, unstable gait and hemifacial spasm. With the aid of modern imaging techniques, such as computed tomography (CT) and magnetic resonance imaging (MRI), an effective microsurgical approach can be planned preoperatively to completely remove tumors and avoid complications.

METHODS

Twenty-six patients with intracranial epidermoid cysts were microsurgically treated between July 1984 and June 1997. Diagnostic procedures included enhanced CT and/or CT cisternography and MRI. All patients underwent microsurgical treatment for tumor removal.

RESULTS

Total tumor removal was achieved in 12 patients (46.2%), near-total removal in seven (26.9%), partial removal in six (23.1%) and stereotactic biopsy in one patient (3.8%). Postoperative deterioration of the neurologic condition was found in three patients who required further surgery, aseptic meningitis in four patients and communicating hydrocephalus requiring shunting in three patients. The functional prognoses were excellent in 23 patients (88.5%), good in two patients (7.7%) and fair in one patient (3.8%). Among the 26 patients, three died of pneumonia three, six and nine months after surgery, respectively.

CONCLUSIONS

MRI is particularly useful for defining the anatomic limits of tumor tissue and surgical planning. The surgical results were excellent in patients with near-total tumor removal, as well as in patients with total removal. Aggressive surgical tumor removal may result in transient, but significant, cranial nerve palsy and should be avoided. Perioperative administration of steroids and wound protection may be beneficial for preventing the development of postoperative aseptic meningitis and hydrocephalus.

Surgical management of intracranial arteriovenous malformation associated with aneurysms

BACKGROUND

The association of intracranial arteriovenous malformation (AVM) with aneurysm(s) is hazardous, and various forms of treatment have been suggested. Most authors agree that surgery for these combined lesions should be directed toward the symptomatic lesion first. This may be difficult, however, especially when the source of the hemorrhage is unclear.

METHODS

Between 1985 and 1996, 12 patients with combined AVM and aneurysm(s) were treated at this institution. Clinical presentations included headache and hemorrhage in all patients, limb weakness in three patients, and seizure in one patient. Hemorrhage types included subarachnoid hemorrhage (SAH), intracerebral hemorrhage (ICH) and intraventricular hemorrhage (IVH). To avoid the intraoperative rupture of aneurysms during resection of the AVM, these were routinely clipped first, followed by total extirpation of the AVM.

RESULTS

SAH, ICH and/or IVH simultaneously presented in seven patients (58.3%). According to the surgical findings, bleeding resulted from the aneurysm in 10 patients and AVM in two patients. There was a high incidence of combined lesions in the posterior circulation (67%) in our series. Among the patients with combined lesions in the posterior circulation, half had multiple aneurysms. A total of 21 aneurysms were found in the 12 patients, with five patients harboring multiple aneurysms. Among the 12 patients, 10 had good results. Eight patients received one-stage operations and two received two-stage operations. Two patients died, one of massive rebleeding from multiple giant aneurysms with SAH, IVH and ICH after ventricular drainage, and the other died of massive bleeding during resection of a large AVM.

CONCLUSIONS

It is difficult to predict bleeding sources preoperatively by radiologic images. Our experience has led to the belief that the safest approach is to treat the aneurysm before microsurgical resection of the AVM. Most of our patients were surgically treated in one approach and showed good results.

Tuberculum sellae meningiomas: clinical manifestation, radiologic diagnosis, surgery and visual outcome

BACKGROUND

Most patients with tuberculum sellae meningioma (TSM) present with visual symptoms mimicking a pituitary macroadenoma. Accurate preoperative differentiation is important because TSM requires a craniotomy, whereas the transsphenoidal route is preferred for removal of most pituitary macroadenomas.

METHODS

From 1989 to 1994, five patients with TSM were treated at Taichung Veterans General Hospital. All were female, ranging in age from 20 to 60 years. This paper is a retrospective review of clinical features, diagnostic methods, treatment and postoperative visual recovery.

RESULTS

The most common symptom, with a duration of one month to two years, was asymmetrical visual loss. Abnormal endocrine levels were found in one patient (prolactin: 47.91 ng/ml). Another patient was misdiagnosed as having a pituitary adenoma by coronal view computed tomography (CT) and underwent a transsphenoidal operation. Later, an accurate diagnosis was made using magnetic resonance imaging (MRI). She then underwent another operation--unilateral subfrontal craniotomy with total removal of the tumor. The other patients were preoperatively diagnosed as having meningioma by MRI. They also underwent unilateral subfrontal craniotomy with total removal of tumor. All patients showed good visual improvement after their operation. The extent of visual improvement was closely related to the duration of preoperative visual loss. There was no tumor recurrence after a follow-up period of six months to five years (mean, two years and six months).

CONCLUSIONS

It should be emphasized that the diagnosis of TSM must first be based on clinical symptoms and signs, or "chiasma-syndrome". It can be accurately diagnosed preoperatively by sagittal view MRI. Early diagnosis will increase the chances of a good postoperative visual outcome.

Molecular origin of the mosaic sequence arrangements of higher primate alpha-globin duplication units

The human adult alpha-globin locus consists of three pairs of homology blocks (X, Y, and Z) interspersed with three nonhomology blocks (I, II, and III), and three Alu family repeats, Alu1, Alu2, and Alu3. It has been suggested that an ancient primate alpha-globin-containing unit was ancestral to the X, Y, and Z and the Alu1/Alu2 repeats. However, the evolutionary origin of the three nonhomologous blocks has remained obscure. We have now analyzed the sequence organization of the entire adult alpha-globin locus of gibbon (Hylobates lar). DNA segments homologous to human block I occur in both duplication units of the gibbon alpha-globin locus. Detailed interspecies sequence comparisons suggest that nonhomologous blocks I and II, as well as another sequence, IV, were all part of the ancestral alpha-globin-containing unit prior to its tandem duplication. However, sometime thereafter, block I was deleted from the human alpha1-globin-containing unit, and block II was also deleted from the alpha2-globin-containing unit in both human and gibbon. These were probably independent events both mediated by independent illegitimate recombination processes. Interestingly, the end points of these deletions coincide with potential insertion sites of Alu family repeats. These results suggest that the shaping of DNA segments in eukaryotic genomes involved the retroposition of repetitive DNA elements in conjunction with simple DNA recombination processes.

Vascular dementia of Binswanger's type: clinical, neuroradiological and 99mTc-HMPAO SPET study

In 24 patients with vascular dementia of Binswanger's type (VDBT) and 14 age-matched neurologically normal volunteers, we investigated the relationship between clinical features, white matter lesions (leuco-araiosis) and cerebral atrophy on computed tomographic (CT) scan, and regional cerebral blood flow. All subjects underwent the Mini-Mental State Examination of Taiwan, version 1 (MMSE-T1), for assessing the severity of cognitive impairment. The patients were subdivided into two groups, one with mild to moderate (group I, MMSE-T1 scores: 11-24, n=11), and the other with severe dementia (group II, MMSE-T1 scores: below 10, n=13). White matter degeneration was evaluated with densitometric methods. Loss of brain parenchyma was estimated with seven linear measurements (Evan's ratio, third ventricle ratio, width of temporal horn tip, anterior-posterior length of temporal horn, anterior-posterior length of Sylvian fissure and width of frontal interhemispheric fissure) by CT scans. Regional cerebral blood flow was determined with technetium-99m hexamethylpropylene amine oxime (HMPAO) single-photon emission tomography (SPET). In neuroimaging studies, subcortical leuco-araiosis was localized at the frontal region in group I patients and scattered diffusely in group II patients. 99mTc-HMPAO SPET analysis revealed reduction of regional cerebral blood flow in the frontal lobe in group I patients and widespread reduction of regional cerebral blood flow in group II patients. A correlation between frontal leuco-araiosis and perfusion defect of the frontal pole was demonstrated in group I patients, showing findings typical of subcortical dementia. There was no difference in frontal atrophic measurements between group I patients and controls. Ratios of volumes of lost brain parenchyma and leuco-araiosis were significantly higher in group II patients than in the age-matched controls, corresponding to a diffuse cerebral perfusion defect. These results suggest that patients with VDBT have early frontal lobe involvement with posterior progression. Patients with mild VDBT are more likely to show reduction of frontal cerebral blood flow and leuco-araiosis, while those with severe VDBT are more likely to have diffuse leuco-araiosis, cerebral hypoperfusion and brain atrophy.

New prenylflavones from the leaves of Epimedium saggitatum

Five new prenylflavones, yinyanghuo A (1), yinyanghuo B (2), yinyanghuo C (3), yinyanghuo D (4), and yinyanghuo E (5), along with six known flavonoids, chrysoeriol, quercetin, apigenin, apigenin 7,4'-dimethyl ether, kaempferol, and luteolin, were isolated from the leaves of Epimedium sagittatum. Their structures were determined from spectral analysis. Compounds 1 and 2 showed significant antiplatelet induced by arachidonic acid.

Repair of mitochondrial DNA damage induced by bleomycin in human cells

Damage to mitochondrial DNA (mtDNA) has recently been associated with a variety of human diseases including cancer, diabetes mellitus, and aging. The mechanisms by which the mitochondria respond to DNA damage are of prime importance in understanding how damage can persist and cause disease. Here we demonstrate the repair of mitochondrial DNA damage induced by the naturally occurring, radiomimetic drug bleomycin. WI-38 cells were first permeabilized using 20 micrograms/ml lysophosphatidylcholine in order to increase the intracellular concentration of bleomycin. Dose response studies with the permeabilized cells showed that a concentration of 5 micrograms/ml bleomycin given for 30 min caused sufficient DNA damage for repair studies. Following treatment with this concentration of bleomycin, repair of mtDNA damage was found to be about 80% by 2 h. However, after 4 h no additional repair was observed. The results indicate that there is an efficient DNA repair system in human mitochondria for some types of damage caused by bleomycin. However, there is a component of damage caused by this agent that either is not repaired or is removed at a much slower rate.

Isodicentric Y chromosome: cytogenetic, molecular and clinical studies and review of the literature

Dicentrics are among the most common structural abnormalities of the human Y chromosome. Predicting the phenotypic consequences of different duplications and deletions of dicentric Y chromosomes is usually complicated by varying degrees of mosaicism (45,X cell lines), which may, in some cases, remain undetected. Molecular studies in patients with dicentric Y chromosomes have been few, and only two studies have attempted to determine the presence of SRY (the putative testis-determining factor gene). We report an 18-year-old female with short stature, amenorrhea, hirsutism, hypoplastic labia minora, and clitoromegaly who has a 45,X/46,X,idic(Y)(p11.32)/47,X,idic(Y)(p11.32),idic(Y) (p11.32) karyotype. Southern analysis using Y-specific probes (Y97, 2D6, 1F5, pY3.4) and polymerase chain reaction (PCR) analysis using primers for ZFY and SRY were positive for all loci tested, indicating that almost all of the Y chromosome was present. Our findings and an extensive review of the literature emphasize the importance of molecular analyses of abnormal Y chromosomes before any general conclusions can be reached concerning the relative effects of the Y-chromosome abnormality and mosaicism on sexual differentiation.

Brown-Séquard syndrome associated with Horner's syndrome in cervical epidural hematoma

STUDY DESIGN

This report analyzed the likely locations of lesions that cause a combination of Horner's and Brown-Séquard syndromes. One must know the anatomic structure of spinal cord and the sympathetic nerve chain.

OBJECTIVES

A hypertensive patient had Brown-Séquard and Horner's syndromes after neck trauma. The magnetic resonance imaging and surgical findings showed the correlation between the clinical symptoms and the likely lesion.

METHODS

The patient underwent right hemilaminectomy from C2 to C6 with total removal of hematoma.

CONCLUSION

The spinal epidural hematoma rarely is a surgical emergency. The patient presented with Brown-Séquard and Horner's syndromes. Magnetic resonance imaging made a rapid and correct diagnosis. The patient received an emergent right hemilaminectomy from C2 to C6 with removal of hematoma and subsequently made a complete recovery.

Repeat operations in failed microvascular decompression for trigeminal neuralgia

For the study of pathogenesis and treatment of recurrent trigeminal neuralgia, we performed 31 repeat operations from among 400 patients with trigeminal neuralgia in the past 10 years. Initially, of these 400 patients, 376 underwent microvascular decompression only, and 24 underwent partial sensory rhizotomy with or without microvascular decompression. Fifty-three patients (14%) had recurrences after microvascular decompression, of which 31 patients underwent repeat operations. Among the repeat operations, there was negative exploration in 16 patients (52%), arterial loop compression in 7 (22%), venous compression in 4 (13%), and Teflon compression or adhesion in 4 (13%). Twenty-one patients had early recurrences within 1 year, and 10 patients had late recurrences. Negative exploration and arterial compression were more likely in early recurrence (P = 0.01). Continuing demyelination might occur in patients with negative exploration, even when adequate decompression had been initially performed. Seventy percent of the patients had no recurring pain by way of partial sensory rhizotomy for negative explorations, redecompression of arterial loops, division of offending veins, or lysis and reposition of Teflon. About half of the patients had positive findings that were amenable without rhizotomy in the repeat operations. A repeat operation for failed microvascular decompression is a good choice if the condition of the patient is tolerant.

SRVX, a sex reversing locus in Xp21.2-->p22.11

Duplication within Xp21 causes female or intersexual development in human embryos with an XY chromosome complement. We have mapped the responsible gene, SRVX (sex reversal X), in XY-sex-reversed maternal half siblings who had inherited the duplication from their mother. The limited size of the duplication in our cases, relative to its extent in other similar cases, allows assignment of the SRVX locus to Xp21.2-->p22.11. We infer that SRVX is part of a pathway of sex-determining genes that includes SRY and SRA1, the latter recently assigned to chromosome 17q. If mutation of SRA1 or SRVX can reverse the sex of the XY fetus, this would explain why mutation within SRY is found only sporadically in women with XY gonadal dysgenesis.