Dendrimer-platinate: a novel approach to cancer chemotherapy

A polyamidoamine (PAMAM) dendrimer generation 3.5 with a sodium carboxylate surface was conjugated to cisplatin giving a dendrimer-platinate (dendrimer-Pt; 20-25 wt% platinum) which was highly water soluble and released platinum slowly in vitro. In vivo the dendrimer-Pt and cisplatin were equi-active i.p. against i.p. L1210, and at high dose dendrimer-Pt given i.p. showed activity against i.p. B16F10 whereas cisplatin did not. Additionally, when administered i.v. to treat a palpable s.c. B16F10 melanoma, the dendrimer-Pt displayed antitumor activity whereas cisplatin was inactive. Measurement of platinum levels in blood and tissues after i.v. injection of cisplatin (1 mg/kg) or dendrimer-Pt (15 mg/kg)-the maximum tolerated dose (MTD) of these compounds-showed selective accumulation of the dendrimer-Pt in solid tumor tissue by the EPR effect (a 50-fold increase in area under curve compared with cisplatin). The dendrimer-Pt was also less toxic (3- to 15-fold) than cisplatin and thus has potential for further investigation as a novel antitumor approach.

Extensive sequence divergence and phylogenetic relationships between the fusogenic and nonfusogenic orthoreoviruses: a species proposal

The orthoreoviruses can be divided into subgroups based on either their restricted host range or the unusual ability of certain members of this group of nonenveloped viruses to induce cell-cell fusion from within. Phylogenetic relationships cannot be inferred based on these biological properties because fusogenic reoviruses are present in both the avian and mammalian subgroups. To address this issue, the complete nucleotide sequences of the three S-class genome segments encoding the major sigma-class core, outer capsid, and nonstructural proteins of four fusogenic reoviruses were determined and used to establish the phylogeny of the orthoreoviruses. The viruses analysed included two strains of avian reovirus and the only known fusogenic mammalian reoviruses, Nelson Bay virus and baboon reovirus. Comparative sequence analysis of these fusogenic reoviruses and the prototypical nonfusogenic mammalian reoviruses indicated a highly diverged genus with both conserved and unique sequence-predicted structural motifs in the major sigma-class proteins. Phylogenetic analysis provided the basis for the first taxonomic subdivision of the orthoreoviruses into species classes based on inferred evolutionary relationships. It is proposed that the orthoreoviruses consist of at least four species that separate into three clades. The nonfusogenic mammalian reovirus species represent a single clade, and the fusogenic reoviruses separate into two distinct clades. The first clade of fusogenic reoviruses contains the avian reovirus- and Nelson Bay virus-type species, with the second clade being occupied by the single baboon reovirus isolate that represents a fourth orthoreovirus species.

Comparison of the beluga whale (Delphinapterus leucas) expressed genes for 5-aminolevulinate synthase with those in other vertebrates

The cDNA and inferred amino acid sequences were determined for beluga whale (Delphinapterus leucas) erythroid (E) and housekeeping (H) forms of 5-aminolevulinate synthase (ALS), and they were compared with known sequences for five other vertebrates with particular attention to regulatory features. The cDNAs for whale ALS-E and -H encode, respectively, proteins of 582 and 640 amino acids. Sequence alignments suggest that the whale ALS-H, like those for rat and chicken, has an N-terminal mitochondrial targeting sequence of 56 amino acids. There is a high degree of amino acid conservation between the beluga whale proteins and those of other vertebrates, including regulatory elements and functional residues that have been defined in other ALSs. Both whale proteins contain three heme regulatory motifs suggesting that mitochondrial uptake may be regulated by heme. The ALS-E mRNA contains an iron responsive element in its 5'-untranslated region indicating that its expression may be post-transcriptionally regulated by cellular iron. This extensive structural similarity and the presence of the same regulatory elements found in other ALSs indicate that regulation of ALS in beluga whale is similar to that in other vertebrates.

HPMA copolymer platinates as novel antitumour agents: in vitro properties, pharmacokinetics and antitumour activity in vivo

The aim of this study was to compare in vitro and in vivo HPMA copolymer platinates with cisplatin in terms of platinum release, toxicity and antitumour activity. N-(2-hydroxypropyl)methacrylamide (HPMA) conjugates containing peptidyl side-chains (Gly-Gly or Gly-Phe-Leu-Gly) terminating in either carboxylate or amino species were prepared. The carboxylate polymeric intermediate was reacted with cisplatin, and the polymeric diamine with potassium tetrachloroplatinate to produce HPMA copolymer platinates of Mw 25,000-31,000 Daltons with a platinum loading of 3-7 wt%. The diglycyl spacer was selected because it is non-biodegradable, whereas the tetrapeptide spacer is known to be cleaved by the lysosomal thiol-dependent proteases. In vitro the HPMA copolymer platinates displayed a range of platinum release rates at pH 7.4 and 5.5; from < 5%/24 h in the case of the diamino species which require enzymatic activation, to > 80%/24 h in the case of the carboxylate. Cisplatin and the fast releasing carboxylate species displayed IC50 values of 10 micrograms/ml Pt-equivalent against B16F10 cells in vitro, whereas the slow releasing conjugates were not cytotoxic over the dose range studied. Antitumour activity of HPMA copolymer platinates was first evaluated against L1210 and B16F10 tumours inoculated intraperitoneally (i.p.). When conjugates were administered i.p., the antitumour activity observed against L1210 tumours was within the range seen for free cisplatin (ratio of mean survival of treated animals to mean survival of controls, T/C, 1.20-1.70). Neither cisplatin nor HPMA copolymer platinates were active against intraperitoneal (i.p.) B16F10 tumours when administered i.p. However, when conjugates were administered intravenously (i.v.) to treat subcutaneous (s.c.) B16F10 tumours grown to palpable size, free cisplatin was still not active but the HPMA copolymer platinates bearing carboxylate and diamine platinates showed significant antitumour activity (T/C > 1.35). Throughout these studies, the polymer platinates were 5-15-fold less toxic than cisplatin in vivo. After i.v. administration, the blood clearance of HPMA copolymer platinate was considerably slower (t1/2 alpha approximately 10 h) than seen for free cisplatin (t1/2 alpha < 5 min). HPMA copolymer platinates (15 mg/kg Pt-equivalent) gave rise to an approximately 60-fold increase in Pt AUC in B16F10 tumour tissue than was achieved after administration of cisplatin at its maximum tolerated dose (MTD) (1 mg/kg).

Regional cerebral perfusion and amytal distribution during the Wada test

The distribution of sodium amytal and its effect on regional cerebral perfusion during the intracarotid amytal (Wada) test were investigated using high-resolution hexamethyl propyleneamine oxime (HMPAO) SPECT coregistered with the patient's MRI dataset.

METHODS

Twenty patients underwent SPECT after intravenous HMPAO injection, and 5 patients had both intravenous and intracarotid injections in a double injection-acquisition protocol.

RESULTS

All patients had hypoperfusion in the territories of the anterior and middle cerebral arteries. Basal ganglia perfusion was preserved in 20 of 25 patients. Hypoperfusion of the entire mesial temporal cortex was seen in 9 of 25 patients. Partial hypoperfusion of the whole mesial cortex or hypoperfusion of part of the mesial cortex was seen in 14 of 25 patients. In 2 of 25 patients, mesial temporal perfusion was unaffected. In 5 patients, the double acquisition showed a distribution of HMPAO delivery matching that of hypoperfusion, except for the following: (a) HMPAO was delivered to the basal ganglia and insula, where there was no hypoperfusion; (b) HMPAO was not delivered to the contralateral cerebellum, which did show hypoperfusion; and (c) in 1 patient, perfusion of the mesial temporal cortex was preserved despite intracarotid delivery of HMPAO.

CONCLUSION

Some degree of hypoperfusion of medial temporal structures occurs in the great majority of patients during the Wada test. Partial inactivation of memory structures is therefore a credible mechanism of action of the test. The double acquisition protocol provided no evidence that mesial temporal structures are inactivated remotely by diaschisis. Perfusion in the basal ganglia and insular cortex is not affected by amytal.

Phylogenetic analysis of the 5-aminolevulinate synthase gene

The evolution of 5-aminolevulinate synthase (ALS) was studied by acquiring sequence data and generating phylogenetic trees. Gene sequences were already available for a variety of vertebrates (which have both a housekeeping and an erythroid form of the gene), fungi, alpha-proteobacteria, and one protist and one protostome. In order to generate representative trees, ALS sequence data were acquired from various deuterostomes and protostomes. The species and tissues selected for study were beluga whale liver, hagfish blood, sea urchin gonadal tissue, cuttlefish hepatopancreas, horseshoe crab hepatopancreas, and bloodworm blood. The new sequences and those previously published were examined for the presence of heme-regulatory motifs (HRMs) and iron-responsive elements (IREs). The HRMs are present in almost all eukaryotic species, which suggests their fundamental role in the regulation of ALS. The IREs are present in all vertebrate erythroid forms of ALS, which indicates that in those animals, expression of the erythroid form of the enzyme and, hence, hemoglobin production can be influenced by the intracellular content of iron. The new sequences were aligned with previously reported ALS sequences, and phylogenetic analyses were performed. The resulting trees provided evidence regarding the timing of the gene duplication event that led to the two forms of the ALS gene in vertebrates. It appears that the housekeeping and erythroid forms of ALS probably arose before the divergence of hagfish from the deuterostome line leading to the vertebrates. The data also add to the evidence indicating that alpha-proteobacteria are the nearest contemporary relatives of mitochondria.

Rubella virus-induced apoptosis varies among cell lines and is modulated by Bcl-XL and caspase inhibitors

Rubella virus (RV) causes multisystem birth defects in the fetuses of infected women. To investigate the cellular basis of this pathology, we examined the cytopathic effect of RV in three permissive cell lines: Vero 76, RK13, and BHK21. Electron microscopy and the TUNEL assay showed that the cytopathic effect resulted from RV-induced programmed cell death (apoptosis) in all three cell lines, but the extent of apoptosis varied among these cells. At 48 h postinfection, the RK13 cell line showed the greatest number of apoptotic cells, the Vero 76 cell line was approximately 3-fold less, and BHK21 had very few. An increased multiplicity of infection and longer time postinfection were required for the BHK21 cell line to reach the level of apoptotic cells in Vero 76 at 48 h. Purified RV induced apoptosis in a dose-dependent fashion, but not UV-inactivated RV or virus-depleted culture supernatant. Specific inhibitors of the apoptosis-specific proteases caspases reduced RV-induced apoptosis and led to higher levels of RV components in infected cells. To address the role of regulatory proteins in RV-induced apoptosis, the antiapoptotic gene Bcl-2 or Bcl-XL was transfected into RK13 cells. Although a high level of Bcl-2 family proteins was expressed, no protection was observed from apoptosis induced by RV, Sindbis virus, or staurosporine in RK13 cells. In BHK21 cells, however, increased expression of Bcl-XL protected cells from apoptosis. The observed variability in apoptotic response to RV of these cell lines demonstrates that programmed cell death is dependent on the unique properties of each cell and may be indicative of how selective organ damage occurs in a congenital rubella syndrome fetus.

Video-EEG and ictal SPECT in three patients with both epileptic and non-epileptic seizures

We report scalp EEG and ictal SPECT findings in epileptic (complex partial) and non-epileptic seizures in three patients who experienced both types of event during presurgical investigation of medically intractable epilepsies. In all three patients, ictal SPECT showed localizing changes in cerebral blood flow during epileptic seizures, but showed no change during pseudoseizures. In two patients, the physical manifestations of the pseudoseizures were similar to those of the epileptic seizures, supporting the contention that physiological activation is unlikely to mimic ictal perfusion changes. In one patient, the EEG recording was rendered difficult to interpret by muscle artefact, while SPECT was clear and showed no change. SPECT is not a primary tool for diagnosis of pseudoseizures, but when patients undergoing presurgical investigation are injected during pseudoseizures, then SPECT is unlikely to show misleading perfusion changes due to activation effects, and may aid diagnosis where there is muscle artefact on EEG.

Potential of low molecular mass chitosan as a DNA delivery system: biocompatibility, body distribution and ability to complex and protect DNA

Cationic polymers have the potential for DNA complexation and it is recognised that they may be useful as non-viral vectors for gene delivery. Highly purified chitosan fractions of < 5000 Da (N1), 5000-10,000 Da (N2) and > 10,000 Daltons (N3) were prepared and characterised in respect of their cytotoxicity, ability to cause haemolysis, ability to complex DNA as well as to protect DNA from nuclease degradation. Also the biodistribution of 125I-labelled chitosans was followed at 5 and 60 min after intravenous injection into male Wistar rats. All chitosan fractions displayed little cytotoxicity against CCRF-CEM and L132 cells (IC50 > 1 mg/ml), and they were not haemolytic (< 15% lysis after 1 and 5 h). Chitosan-DNA interaction at a charge ration of 1:1 was much greater than seen for poly(L-lysine) and complexation resulted in inhibition of DNA degradation by DNase II: 99.9 +/- 0.1, 99.1 +/- 1.5 and 98.5 +/- 2.0% for N1, N2 and N3, respectively. After intravenous injection, all the chitosans showed rapid blood clearance, the plasma levels at 1 h being 32.2 +/- 10.5% of recovered dose for N1 and 2.6 +/- 0.5% of recovered dose for N3. Liver accumulation was molecular mass dependent, being 26.5 +/- 4.9% of the recovered dose for N1 and 82.7 +/- 1.9% of the recovered dose for N3. The observations that the highly purified chitosan fractions used were neither toxic nor haemolytic, that they have the ability to complex DNA and protect against nuclease degradation and that low molecular weight chitosan can be administered intravenously without liver accumulation suggest there is potential to investigate further low molecular weight chitosans as components of a synthetic gene delivery system.

Phase I clinical and pharmacokinetic study of PK1 [N-(2-hydroxypropyl)methacrylamide copolymer doxorubicin]: first member of a new class of chemotherapeutic agents-drug-polymer conjugates. Cancer Research Campaign Phase I/II Committee

PK1 comprises doxorubicin covalently bound to N-(2-hydroxypropyl)methacrylamide copolymer by a peptidyl linker. Following cellular uptake via pinocytosis, the linker is cleaved by lysosomal enzymes, allowing intratumoral drug release. Radically altered plasma and tumor pharmacokinetics, compared to free doxorubicin, and significant activity in animal tumors have been demonstrated preclinically. We aimed to determine the maximum tolerated dose, toxicity profile, and pharmacokinetics of PK1 as an i.v. infusion every 3 weeks to patients with refractory or resistant cancers. Altogether, 100 cycles were administered (range, 20-320 mg/m2 doxorubicin-equivalent) to 36 patients (20 males and 16 females) with a mean age of 58.3 years (age range, 34-72 years). The maximum tolerated dose was 320 mg/m2, and the dose-limiting toxicities were febrile neutropenia and mucositis. No congestive cardiac failure was seen despite individual cumulative doses up to 1680 mg/m2. Other anthracycline-like toxicities were attenuated. Pharmacokinetically, PK1 has a distribution t(1/2) of 1.8 h and an elimination t(1/2) averaging 93 h. 131I-labeled PK1 imaging suggests PK1 is taken up by some tumors. Responses (two partial and two minor responses) were seen in four patients with NSCLC, colorectal cancer, and anthracycline-resistant breast cancer. PK1 demonstrated antitumor activity in refractory cancers, no polymer-related toxicity, and proof of principle that polymer-drug conjugation decreases doxorubicin dose-limiting toxicities. The recommended Phase II dose is 280 mg/m2 every 3 weeks. Studies are planned in colorectal, NSCLC, and breast cancer patients.

Characterization of two avian reoviruses that exhibit strain-specific quantitative differences in their syncytium-inducing and pathogenic capabilities

We previously proposed that the conservation of the nonessential syncytium-inducing phenotype among all reported avian reovirus (ARV) isolates may reflect a mechanism for enhanced virus dissemination in vivo, which in turn could contribute to the natural pathogenicity of ARV. Direct testing of this hypothesis has been hampered by the lack of available virus strains with defined differences in their fusion-inducing capability. We now report on the characterization of two ARV strains, ARV-176 and ARV-138, that exhibited strain-specific differences in their fusogenic properties, which correlated with their pathogenic potential in embryonated eggs. Moreover, both virus strains possessed similar replicative abilities in cell culture, suggesting that the weakly fusogenic ARV-138 virus is specifically inhibited in its syncytium-inducing ability. To test the use of these viruses for reassortant studies aimed at assessing the role of cell fusion in viral pathogenesis, a preliminary genetic analysis was undertaken using a monoreassortant that contained nine genome segments from the parental ARV-138 virus and the S1 genome segment from the highly fusogenic and pathogenic ARV-176 parental virus. The monoreassortant possessed the full fusogenic potential of the ARV-176 parental virus and displayed enhanced embryo pathogenicity, providing the first genetic evidence implicating the ARV S1 genome segment in both syncytium formation and viral pathogenesis.

Characterization of mRNA for hepatitis delta antigen: exclusion of the full-length antigenomic RNA as an mRNA

Hepatitis delta virus (HDV) encodes a single protein, the hepatitis delta antigen (HDAg), which is thought to be translated from a 0. 8-kb RNA of antigenomic sense. This subgenomic RNA species is present in very small amounts in HDV-infected liver tissues and in cultured cells infected or transfected with HDV, and in some cases it cannot be detected at all. In contrast, HDAg protein is present in large amounts in all natural and experimental models of HDV infection. This study addresses whether other HDV RNA species, such as the antigenomic-sense, genome-size HDV RNA can also serve as the mRNA for HDAg synthesis. Taking advantage of the ability of herpes simplex virus (HSV) to degrade only polyadenylated mRNAs, we examined the effect of HSV coinfection on HDAg synthesis. It was shown that HSV infection did degrade the subgenomic 0.8-kb HDV mRNA but not HDV genome-length RNA. Under such conditions, HDAg synthesis was completely inhibited. Furthermore, the genome-length HDV RNA was found not to be associated with polysomes. Finally, in vitro translation studies demonstrated that HDAg could not be translated directly from the genome-length antigenomic-sense HDV RNA. These results suggest that only the subgenomic RNA species of HDV possesses properties characteristic of the mRNA for HDAg and that the genome-length RNA cannot be used for translating HDAg. In addition, we found that HDV RNA replication did not depend on de novo HDAg synthesis.

Solid waste and pancreatic cancer: an ecologic study in Florida, USA

BACKGROUND

Other than cigarette smoking, modifiable risk factors for pancreatic cancer have not been consistently identified. This study explored the ecologic relationship between pancreatic cancer incidence and measures of cigarette smoking, income, and solid waste collection for Florida's 67 counties.

METHODS

We used Florida's population-based cancer registry to compare county-specific incidence rates of pancreatic cancer among Whites to median household income, the per county prevalence of cigarette smoking, and to measures of per capita municipal solid waste collected.

RESULTS

County-specific incidence rates for pancreatic cancer ranged from 0 to 8.1 per 100,000 per year and were significantly correlated with income (r = 0.35), cigarette smoking (r = 0.39), and solid waste (r = 0.47). The correlation between pancreatic cancer and solid waste was largely attributable to one sub-component of solid waste, yard trash (grass clippings, and tree and shrub trimmings) (r = 0.42). Using a stepwise regression procedure, only cigarette smoking and yard trash remained significant in the model.

CONCLUSIONS

These data suggest that some factor associated with grass and tree trimmings, e.g. insecticides and herbicides, may increase the risk for pancreatic cancer. This hypothesis is consistent with several reports of pancreatic cancer and insecticide exposure in individuals and may suggest new avenues for research in pancreatic cancer.

Comparison of bimanual examination with ultrasound examination before hysterectomy for uterine leiomyoma

OBJECTIVE

To correlate the preoperative bimanual examination with ultrasound examination with regard to estimating the size of enlarged nongravid leiomyomatous uteri.

METHODS

We performed a retrospective review of 161 patients who underwent hysterectomy for uterine leiomyoma between January 1994 and December 1994 and between July 1995 and April 1996. Uterine size was estimated clinically by bimanual examination. Ultrasound reports were reviewed. Uterine weights and dimensions in pathology reports were compared with findings on bimanual examination and ultrasonography. Body mass index (BMI) was calculated and patients were divided into two groups, one with BMIs of more than 30 and another with BMIs of less than or equal to 30.

RESULTS

Ultrasound examination was ordered in 111 patients (68.9%) preoperatively. There was a strong correlation between the bimanual examination findings and the ultrasound dimensions. The equation for this relationship is ultrasound length (cm)=3.68 + 0.68 x number of weeks (r=.78, P < .001). Ultrasound length also was related strongly to size given in the pathologic reports; the equation for this relationship is ultrasound length (cm)=2.94 + 0.75 x pathology length (cm) (r=.73, P < .001). The correlation between bimanual examination and ultrasound findings was similar in obese and in nonobese patients, when uterine size could be estimated.

CONCLUSION

There is a strong correlation between bimanual and ultrasound examinations with regard to determining the size of leiomyomatous uteri. Routine ultrasound is not indicated when an experienced examiner can assess uterine size. Ultrasonography may be appropriate when physical assessment is difficult, as in the case of obesity.

Early phase tumor accumulation of macromolecules: a great difference in clearance rate between tumor and normal tissues

The objective of this study was to investigate the molecular weight (MW) and time-dependence of the phenomenon termed "the enhanced permeability and retention" (EPR) effect in solid tumor, in particular to determine and define the early phase accumulation of macromolecules in tumor and normal tissues and the relationship between blood concentration and tissue clearance. As a model, radioiodinated N-(2-hydroxypropyl)methacrylamide (HPMA) copolymers of MW ranging from 4.5 K to 800 K were administered i.v. to mice bearing sarcoma 180 tumor. Within 10 min all HPMA copolymers accumulated effectively in the tumor regardless of MW (1.0-1.5% of injected dose per g of tumor). However, higher MW copolymers (> 50 K) showed significantly increased tumor accumulation after 6 h, while the lower MW copolymers (< 40 K) were cleared rapidly from tumor tissue due to rapid diffusion back into the bloodstream. Blood clearance was also MW-dependent; the lower MW copolymers displayed rapid clearance, with kidney radioactivity of the copolymers of MW < 20 K representing 24% of injected dose per g kidney at 1 min after i.v. administration. Within 10 min these copolymers passed through the kidney and were excreted in the urine. Higher MW copolymers consistently showed kidney levels of 3-5% dose per g kidney in the early phase with no time-dependent accumulation in kidney. There was also no progressive accumulation in muscle or liver, regardless of polymer MW. These results suggest the "EPR effect" in solid tumor primarily arises from in the difference in clearance rate between the solid tumor and the normal tissues after initial penetration of the polymers into these tissues.

Preclinical toxicology of a novel polymeric antitumour agent: HPMA copolymer-doxorubicin (PK1)

N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer-doxorubicin (PK1) is a novel polymeric anticancer agent containing doxorubicin (approximately 8 wt%) bound to the polymer backbone via a Gly-Phe-Leu-Gly peptidyl linker. The approximate LD50 of PK1 in MF1 mice after a single i.v. injection was 63 mg/kg (doxorubicin-equivalent). Single doses of PK1 were administered to MF1 mice at 22.5 or 45 mg/kg and blood samples taken on days 3, 7 and 14 for haematological examination and clinical chemistry. At day 14 all animals were sacrificed for necropsy. In a multiple dose study, PK1 was administered i.v. to MF1 mice or Wistar rats (20 animals per group) weekly for five consecutive weeks at doses of 12.0 or 22.5 mg/kg (mice) or 3 and 5 mg/kg (rats). After 31 days 10 animals from each group were sacrificed for necropsy and the remainder were sacrificed after 59 days. Blood samples were taken 3 days after administration of each dose and at the end of the experiment, and urine samples were collected on the day prior to sacrifice. Mortality in the single dose mouse and multiple dose rat studies was low. In the multiple dose mouse study 4/10 animals were killed in extremis before the scheduled day 31 and all animals died before day 37. PK1 induced a reduction in WBC and platelets in rats and mice shortly after treatment and RBC at later times, and in the single dose study alanine and aspartate aminotransferase levels were elevated at higher doses. Liver damage was seen only in rat tissue during histological examination. Other histological changes induced by PK1 include thymic and testicular atrophy, bone marrow depletion gastrointestinal tract changes and in the multiple dose study an increase in nuclear size in the proximal tubules of the kidney (although no changes in urine were seen). Recovery from these effects was seen in rats at 59 days. A PK1 dose of 20 mg/m2 (doxorubicin equivalent) was recommended as a safe dose for the start of Phase I clinical trials.

Correlation between interictal regional cerebral blood flow and depth-recorded interictal spiking in temporal lobe epilepsy

PURPOSE

Single photon emission computed tomography (SPECT) is used as an adjunctive method in preoperative localization of epileptic foci. In temporal lobe epilepsy (TLE), interictal hypoperfusion is observed in 60-70% of cases. Correlation with ictal EEG changes is observed in approximately 50-60% of cases. Relationships with interictal EEG have been studied less. We compared interictal SPECT data obtained in 20 patients with their interictal intracerebral electrical activity recorded by depth electrodes to evaluate a potential relationship.

METHODS

We studied 20 sequential patients whose clinical, surface, and depth EEG data indicated seizure originating in the temporal lobe and who had interictal [99mTc]hexamethylpropylene amine oxime (HMPAO)-SPECT stereo-EEG (SEEG). Intracerebral electrodes were placed according to the patient's profile. The interictal extent of epileptiform activity allowed delineation of the irritative zone. Interictal spike frequency was also analyzed semiquantitatively. Visual and numerical SPECT analysis was performed blind to SEEG data.

RESULTS

Interictal hypoperfusion was observed in 16 patients, involving the epileptogenic temporal lobe in 14. Except for 1 patient who manifested lateral temporal hypoperfusion corresponding to a mass lesion, two distinctive patterns of hypoperfusion were noted: (a) mesial hypoperfusion (5 patients), and (b) global temporal hypoperfusion (8 patients). In 8 patients, hypoperfusion had also extended into the adjacent cortex. Temporal mesial hypoperfusion was associated with spiking limited to the mesial structures, whereas global temporal hypoperfusion or hypoperfusion extending beyond the temporal lobe was associated with a similar topographic pattern of spikes.

CONCLUSIONS

Comparison between SPECT and SEEG data collected in the interictal phase indicated that the extent of the hypoperfused area correlated topographically with that of the underlying irritative zone.

Necrotizing enteritis as a cause of mortality in Laysan albatross, Diomedea immutabilis, chicks on Midway Atoll, Hawaii

A necropsy survey of Laysan albatross, Diomedea immutabilis, chicks on Midway Atoll in June 1993, 1994, and 1995 revealed 54% (21/39), 67% (49/71), and 93% (15/16), respectively, to have enteritis as the most severe pathologic finding. The lesion was limited to the ileum, ceca, and large intestine. We were unable to attribute a single infectious etiology to this lesion. Many birds with enteritis also exhibited renal lesions similar to those encountered in chickens experimentally deprived of water. We propose that enteritis is a significant cause of mortality in Laysan albatross chicks on Midway and that it may be a sequela to dehydration. It is likely that the pathology of dehydration in Laysan albatross differs from that in chickens largely because of diet.

Stroke without dissection from a neck holding manoeuvre in martial arts

Carotid artery trauma is a known cause of stroke in young people. The vessel may occlude, dissect or shower thrombotic emboli into intracranial vessels. This paper reports the use of single photon emission computed tomography (SPECT) imaging in a 29 year old man who developed an embolic stroke after neck holding manoeuvres at a martial arts class. Awareness of the potential consequences of these procedures is matched by the need for rapid and accurate diagnosis of stroke now that thrombolytic and neuroprotective treatments are emerging, which are effective only within a short time window.

Ictal regional cerebral blood flow in frontal lobe seizures

99mTC (single photon emission computed tomography) (HMPAO SPECT) was carried out during 16 frontal-lobe seizures in 15 patients. Focal changes in regional cerebral blood flow were seen during all seizures. In 9 of 16 seizures SPECT showed hyperperfusion localized to one frontal lobe. In 1 of 16 seizures ictal hypoperfusion was seen in one frontal lobe. In 2 of 16 seizures there was hyperperfusion in both frontal lobes, and in 4 of 16 seizures hyperperfusion involved the frontal lobe or lobes plus other lobes of the brain. These changes were accompanied by hyperperfusion of subcortical structures in 13 seizures. SPECT thus localized to one frontal lobe in 10 of 16 seizures, and localized to the frontal lobes without lateralizing in two further seizures. No seizure showed a pattern of perfusion similar to that reported in mesial-temporal-lobe seizures. We conclude that ictal SPECT may provide useful localizing information in frontal-lobe seizures.