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Biomedical subjects

J H Cross

Publications and source records attributed to J H Cross.

At least 19 recordsLinked to original sources
PubMed2003

Clinical outcomes of hemispherectomy for epilepsy in childhood and adolescence.

Hemispherectomy has been performed in the treatment of epilepsy in association with hemiplegia for over 50 years. However, the optimal timing of surgery with respect to age at presentation and the influence of underlying pathology on outcome is only slowly emerging. This study reports on the clinical course and outcomes of 33 children who underwent hemispherectomy at Great Ormond Street Hospital, London, between 1991 and 1997. Age at surgery was 0.33-17 years (median 4.25) with 1-8 years follow-up (median 3.4). The underlying pathology was developmental in 16 (10 hemimegalencephaly, two polymicrogyria, two focal cortical dysplasia, one diffuse cortical dysplasia and one microdysgenesis), acquired in 11 (six middle cerebral artery infarct, three post encephalitis/trauma, and one each of hemiconvulsion-hemiplegia epilepsy and perinatal ischaemic insult) and progressive in six children (four Rasmussen encephalitis, two Sturge-Weber syndrome). At follow-up, 52% were seizure free, 9% experienced rare seizures, 30% showed >75% reduction in seizures and 9% showed <75% seizure reduction or no improvement. Seizure freedom was highest in those with acquired pathology (82%), followed by those with progressive pathology (50%) and those with developmental pathology (31%). However, seizure freedom, rare seizures or >75% reduction in seizures occurred in 100% of those with progressive pathology, 91% of those with acquired and 88% of those with developmental pathology, indicating a worthwhile seizure outcome in all groups. Hemiplegia remained unchanged following surgery in 22 out of 33 children, improved in five and was worse in six. No significant cognitive deterioration or loss of language occurred, and four children showed significant cognitive improvement. Behavioural improvement was reported in 92% of those who had behaviour problems pre-operatively.

Adolescent↗
PubMed2002

Correlation of SPECT with pathology and seizure outcome in children undergoing epilepsy surgery.

SPECT can be used to image regional cerebral blood flow (rCBF) and has been shown to help localize the seizure focus in partial epilepsies as part of the presurgical evaluation. Few studies have explored the possible relation between preoperative SPECT and underlying pathology, or any relation to postsurgical outcome. In this study preoperative ictal and interictal rCBF in relation to the histopathological diagnosis and outcome in a series of 35 children (24 females, 11 males; mean age 9.6 years, age range 11 months to 18 years) who had undergone resective surgery for epilepsy were retrospectively evaluated. A correlation between ictal hyperperfusion and the underlying responsible pathology was shown, with a consistent ictal increase in perfusion in developmental pathologies and Rasmussen's encephalitis, and consistent interictal hypoperfusion in hippocampal sclerosis (HS). No rCBF study parameter appeared to relate to outcome but in the group with HS the best outcome was seen in those with localizing ictal rCBF. The varied group of pathologies from hemispherectomy had excellent outcome but the SPECT findings had little to contribute over the abnormalities detected on MRI. In conclusion, rCBF studies remain a useful presurgical investigation in children with partial epilepsy, especially where HS, cortical dysplasia, or inflammatory disease are the underlying pathology. However, rCBF studies add little to the investigation of children with seizures secondary to benign tumours or cerebral infarcts, or where hemispherectomy is the likely preferred surgical option.

Adolescent↗
PubMed2001

Quantitative magnetic resonance characterization of mesial temporal sclerosis in childhood.

OBJECTIVE: To investigate whether quantitative MR techniques can be used to distinguish between mesial temporal sclerosis in patients with a history of prolonged febrile convulsion and in patients without such a history. METHODS: Quantitative hippocampal T2 relaxometry, hippocampal volumetry, and single voxel (1)H-MRS data were acquired from 16 children who subsequently underwent temporal lobe resections for intractable temporal lobe epilepsy and histologically were shown to have sclerosis of the horn of Ammon. Eight children had a history of prolonged febrile convulsion in early childhood and eight children had other or no associations. RESULTS: Patients with a history of prolonged febrile convulsion had smaller hippocampi (p = 0.02) and prolonged T2 relaxation time (p = 0.03) ipsilateral to the seizure focus when compared with patients without such a history. There was also more side-to-side asymmetry of T2 relaxation time (p = 0.004) and hippocampal volume (p = 0.02) in the patients with a history of prolonged febrile convulsion than in those with other or no associations. No differences between the groups were identified using (1)H-MRS. CONCLUSIONS: These data support the view that there are at least two types of mesial temporal sclerosis. There may be several pathogenetic pathways from initial insult to later mesial temporal sclerosis, and these pathways are, at least in part, dependent on the initial insult.

Adult↗
PubMed2001

Multilocus sequence typing of Streptococcus pyogenes and the relationships between emm type and clone.

Multilocus sequence typing (MLST) is a tool that can be used to study the molecular epidemiology and population genetic structure of microorganisms. A MLST scheme was developed for Streptococcus pyogenes and the nucleotide sequences of internal fragments of seven selected housekeeping loci were obtained for 212 isolates. A total of 100 unique combinations of housekeeping alleles (allelic profiles) were identified. The MLST scheme was highly concordant with several other typing methods. The emm type, corresponding to a locus that is subject to host immune selection, was determined for each isolate; of the >150 distinct emm types identified to date, 78 are represented in this report. For a given emm type, the majority of isolates shared five or more of the seven housekeeping alleles. Stable associations between emm type and MLST were documented by comparing isolates obtained decades apart and/or from different continents. For the 33 emm types for which more than one isolate was examined, only five emm types were present on widely divergent backgrounds, differing at four or more of the housekeeping loci. The findings indicate that the majority of emm types examined define clones or clonal complexes. In addition, an MLST database is made accessible to investigators who seek to characterize other isolates of this species via the internet (http://www.mlst.net).

Alleles↗
PubMed2001

Affinity purified oval antigen for diagnosis of Opisthorchiasis viverrini.

Monoclonal antibodies (MAb) were raised against an oval antigen of the liver fluke Opisthorchis viverrini which is the causative agent of a parasitosis, i.e. opisthorchiasis in Thailand. The antibodies were used in an affinity column to purify the O. viverrini oval antigen from a crude extract of adult parasites by chromatography. The oval antigen was then used in a membrane (dot) ELISA for detecting antibodies in serum samples of parasitologically confirmed Opisthorchis viverrini infected individuals (adult parasites were found in stools after praziquantel treatment and salt purgation), as well as of individuals infected with other parasites and parasite-free controls. The MAb-based dot-ELISA using the affinity purified O. viverrini oval antigen revealed 100% sensitivity, specificity and accuracy for detecting O. viverrini infection. The test is simple, rapid and highly reproducible. Several samples can be tested at the same time without the requirement for special equipment or much increase in testing time; thus it is suitable for mass screening for O. viverrini exposure, especially in new endemic areas. Furthermore using serum specimens could increase patient and community compliance compared to the conventional parasitological survey which uses stool samples for the detection of O. viverrini ova, without treatment and subsequent salt purgation, this conventional method shows a low sensitivity and is also unpleasant to both the sample donors and the laboratory technicians which has historically shown a further negative impact on the final outcome.

Animals↗
PubMed2001

Emerging pathogen Cyclospora cayetanensis infection in Nepal.

Cylospora cayetanensis, an emerging parasitic pathogen of human is being increasingly recognized throughout the world, however the means of transmission and the possibility of a reservoir host remain an enigma. A longitudinal study on cyclosporiasis in different parts of Nepal was carried out from April, 1995 until November, 2000. Fecal specimens were collected from symptomatic and asymptomatic patients. The data shows a distinct seasonality with the highest infection rates occurring during the summer and rainy season of the year. Attempts have been made to determine the sources of infection and possible reservoir hosts. Stools were examined from nearly 700 animals such as chickens, pigs, buffalos, cows, dogs, cats, monkeys, rats, mice and pigeons. In addition, vegetable farms around the Kathmandu Valley were examined during the seasonal high and low periods of transmission. C. cayetanensis-like oocysts were found in sewage water and from vegetable washings on five occasions during June, July, August, October, and November. Similarly, C. cayetanensis-like oocysts were recovered from mice, rats, chickens, and dogs. These results suggest that these sources may be important in the transmission of this parasitosis. However, further studies will be required to obtain definitive answers on transmission.

Adolescent↗
PubMed1999

Autistic spectrum disorders in childhood epilepsy surgery candidates.

One third of children with autistic spectrum disorders (or pervasive developmental disorders) enter that state by regression from a more normal prior development at the onset of epilepsy or epileptiform abnormality in the electroencephalogram. In a very small proportion structural lesions of the temporal lobes are discovered. These form part of the sample of children coming to a surgical treatment programme. Ninety-eight child candidates for epilepsy surgery were seen by one neuropsychiatrist. Their psychiatric diagnoses were coded on DSM IV schedules. Other variables of interest were the age at onset of epilepsy; the nature, the side, and time of acquisition of the lesion; intelligence, and sex. There were 19 children with autistic spectrum disorders including eight with Asperger's syndrome. Ten of the children in the autistic group had right brain lesions; six were dysembryoplastic neuroepithelial tumours (DNETs); two were cortical dysplasias; one tuberous sclerosis; one hemi-cortical defect; and 1 mesial temporal sclerosis. Nine started epilepsy in their first year; nine had IQs in the retarded range; nine of the 11 were male. Six of eight Asperger's children had right brain lesions; two DNETs; four mesial temporal sclerosis; one Rasmussen encephalitis. Four started epilepsy in their first year; one was retarded; five were female. Children who had no, or other, psychiatric disorder also showed "mass" lesions, or temporal sclerosis but with different biases as to side, sex, and very early onset of epilepsy from the autistic spectrum group. Very early onset of epilepsy, with lesions of embryonal origin, in the right temporal lobe, strongly predisposed males towards autistic regression. Such patients should be referred very early for consideration of urgent surgical treatment.

Age of Onset↗
PubMed1999

Ictal hemiparesis.

Two subjects with ictal hemiparesis are described. Both children presented with evolving paresis associated with seizure activity. Structural neuroimaging remained consistently normal, although EEG demonstrated slow-wave activity, and SPECT scanning in one child showed perfusion asymmetry. Both children had resolution of the hemiparesis when seizure activity was adequately controlled. The historically proposed pathophysiology of ictal hemiparesis is that of inhibition of the somatosensory and motor areas of the cortex. The presence of an evolving hemiparesis and seizure activity associated with normal neuroimaging should prompt consideration of ictal hemiparesis. Confirmation of this rare diagnosis can only be made when seizure control leads to resolution of the paresis.

Child↗
PubMed1999

Sturge-Weber syndrome: cerebral haemodynamics during seizure activity.

The aim of this study was to examine the haemodynamic response to seizures in three infants with Sturge-Weber syndrome by measuring regional cerebral blood flow using transcranial Doppler sonography and 99mTc HMPAO SPECT. Time-locked video/digital EEG recording was carried out for ictal studies. MRI was performed in all subjects. SPECT showed hemispheric hypoperfusion interictally in all three patients and also ictally in one of the three; a small region of hyperperfusion was seen on the same ictal scan in the latter, ie. the patient with interictal and ictal hypoperfusion. In the two older children middle cerebral artery velocity (MCAV) was reduced by between 29 and 62% in the middle cerebral artery of the predominantly affected hemisphere compared with the contralateral side. During seizures, increases of 6 to 30% in MCAV were recorded for the clinically seizing hemisphere compared with 24 to 170% for the contralateral side in four of the seizures recorded. In one infant, MCAV fell bilaterally during a seizure that generalized (-18 and -43% in the predominantly affected and contralateral side respectively). Sequential recordings in one infant suggested that, with time, the haemodynamic response to seizures of the unaffected hemisphere may decrease. These findings suggest that the venous malformation in SWS is associated with an impairment of the cerebral haemodynamic response to seizure activity.

Cerebral Cortex↗
PubMed1999

Study of Cyclospora cayetanensis in health care facilities, sewage water and green leafy vegetables in Nepal.

Cyclospora cayetanensis, a newly emerging parasite, is endemic in Nepal. A total of 2,123 stool specimens were collected from 3 health care facilities based on clinical symptoms during the period between 1995 to October, 1998. Out of these specimens, cayetanensis oocysts were found in 632 (29.8%). To identify possible sources for Cyclospora infection, drinking water, sewage water, green-leafy vegetables including fecal samples of various animals were collected and examined. The vegetable leaves were washed in distilled water then the washings, sewage water and drinking water were centrifuged and the sediment were examined microscopically. As a result, oocyst of Cyclospora were identified in sewage water and vegetable washings on four different occasions in June, August, October and November. The positive results were also confirmed as C. cayetanensis by development of 2 sporocysts after 2 week incubation period in potassium dichromate. A survey of 196 domestic animals from the same areas demonstrated that two chickens were positive for Cyclospora-like organism and others were negative. Although further studies are needed to clarify the direct link between Cyclospora infection and these sources, the results suggest that sewage water, green leafy vegetables are possible sources of infection and chickens could be possible reservoir host of Cyclospora in Nepal.

Adolescent↗
PubMed1998

Fibrin glue terminates massive bleeding after complex hepatic injury.

OBJECTIVE: We determined the ability of a packaged fibrin glue (FG) product to terminate severe bleeding in a new porcine model of complex hepatic injury. METHODS: Femoral arterial and venous catheters were placed in pentobarbital-anesthetized swine (n=7 per group, 16-18 kg). Pigs received an external blast to the right upper abdomen at 0 minutes, followed by uncontrolled hemorrhage at 0 to 30 minutes, with anticoagulation (heparin, 200 U/kg) at 10 minutes. Pigs were resuscitated with lactated Ringer's solution (20 mL/kg) beginning at 15 minutes and then underwent laparotomy to control bleeding at 30 minutes. Lactated Ringer's solution was infused to keep mean arterial pressure greater than 70 mm Hg until 120 minutes, when repeat laparotomy was performed. Control animals (group 1) underwent routine surgical procedures to terminate bleeding followed by packing if hepatic bleeding continued. The FG animals (group II) underwent routine surgical procedures plus application of FG. Avoidance of packing, estimated blood loss (EBL) during and after laparotomy, and fluid resuscitation volume were the primary end points studied. RESULTS: In both groups, mean arterial pressure varied significantly from baseline to 120 minutes (group I: 100+/-3 to 52+/-11 mm Hg; group II: 99+/-4 to 66+/-3 mm Hg). Temperature decreased at the end of each experiment (group I: 37+/-1 to 33+/-1 degrees C; group II: 37+/-1 to 34+/-1 degrees C). There were no group differences in EBL before laparotomy (0-30 minutes), but from initial laparotomy to repeat laparotomy (30-120 min), EBL (group I: 875+/-265 mL; group II: 300+/-59 mL) and total fluid resuscitation (group I: 2.9+/-0.4 L; group II: 1.9+/-0.3 L) were statistically significantly less in FG pigs. Of greatest importance, six of seven control pigs required packing, but none of the FG animals were packed and none bled at repeat laparotomy. CONCLUSION: FG stopped bleeding and eliminated the need for packing in a model of severe liver injury. Further work in the clinical arena is warranted to determine the potential benefits of FG in arresting hemorrhage in hypotensive, hypothermic, coagulopathic trauma patients with complex visceral injuries.

Animals↗
PubMed1997

Determination of ammonia in ethylene using ion mobility spectrometry.

A simple procedure to analyze ammonia in ethylene by ion mobility spectrometry is described. The spectrometer is operated with a silane polymer membrane., 63Ni ion source, H+ (H2O)n reactant ion, and nitrogen drift and source gas. Ethylene containing parts per billion (ppb) (v/v) concentrations of ammonia is pulled across the membrane and diffuses into the spectrometer. Preconcentration or preseparation is unnecessary, because the ethylene in the spectrometer has no noticeable effect on the analytical results. Ethylene does not polymerize in the radioactive source. Ethylene's flammability is negated by the nitrogen inside the spectrometer. Response to ammonia concentrations between 200 ppb and 1.5 ppm is near linear, and a detection limit of 25 ppb is calculated.

Air↗
PubMed1997

Surgical treatment of severe autistic regression in childhood epilepsy.

We report 2 children with partial epilepsy who manifested social and language regression and partial recovery after surgical treatment. One child had seizures since the first 2 weeks of life, caused by a right temporal dysembryoplastic neuroepithelial tumor and regression in the latter part of the first year; seizures were relieved and some functions were recovered after temporal lobe resection at 12 months of age. The second child developed epilepsy at 3 years 3 months, and between 5 years 9 months and 6 years 1 month he became aphasic (Landau-Kleffner syndrome) and lost social functioning, manifesting a very severe behavior disorder. He exhibited a significant improvement in communication, social functioning, and behavior after left multiple subpial transections. Both children manifested evidence of subclinical seizure activity in both temporal lobes. Their clinical picture was one of combined language and autistic regression, and the autistic features demonstrated a clear response to surgical treatment. We suggest that in pediatric epilepsy surgical programs, autistic regression should prompt urgent investigation if drug treatment is not effective.

Autistic Disorder↗
PubMed1997

Interictal 99Tc(m) HMPAO SPECT and 1H MRS in children with temporal lobe epilepsy.

PURPOSE: To understand the pathological basis of focal hypoperfusion seen on interictal 99Tc(m) hexamethylpropyleneamine oxime (HMPAO) single-photon-emission computed tomography (SPECT) in intractable temporal lobe epilepsy, and to determine why the technique may be misleading in the localization and lateralization of the seizure focus in some cases. METHODS: Interictal 99Tc(m) HMPAO SPECT and proton magnetic resonance spectroscopy (1H MRS) of the mesial temporal regions were performed in 14 children with intractable temporal lobe epilepsy not caused by a foreign tissue lesion. RESULTS: Hypoperfusion of one temporal lobe ipsilateral to the seizure focus was demonstrated in 10 (71%) of the children; 1H MRS correctly lateralised in eight of these 10. No asymmetry of perfusion of the anterior temporal regions was seen in the remaining four children; on 1H MRS, three of these were bilaterally abnormal but nonlateralising. Repeated SPECT and 1H MRS in three children demonstrated changes over time, the findings from the two techniques being consistent with each other on both the initial and the repeated scans. CONCLUSIONS: Abnormalities demonstrated by 1H MRS correlate well with those seen on interictal SPECT and can help to understand the pathologic basis of these SPECT abnormalities. Furthermore, the presence of bilateral damage can result in an absence of perfusion asymmetry on interictal SPECT.

Adolescent↗