A single immunization with CoVaccine HT-adjuvanted H5N1 influenza virus vaccine induces protective cellular and humoral immune responses in ferrets

Highly pathogenic avian influenza A viruses of the H5N1 subtype continue to circulate in poultry, and zoonotic transmissions are reported frequently. Since a pandemic caused by these highly pathogenic viruses is still feared, there is interest in the development of influenza A/H5N1 virus vaccines that can protect humans against infection, preferably after a single vaccination with a low dose of antigen. Here we describe the induction of humoral and cellular immune responses in ferrets after vaccination with a cell culture-derived whole inactivated influenza A virus vaccine in combination with the novel adjuvant CoVaccine HT. The addition of CoVaccine HT to the influenza A virus vaccine increased antibody responses to homologous and heterologous influenza A/H5N1 viruses and increased virus-specific cell-mediated immune responses. Ferrets vaccinated once with a whole-virus equivalent of 3.8 microg hemagglutinin (HA) and CoVaccine HT were protected against homologous challenge infection with influenza virus A/VN/1194/04. Furthermore, ferrets vaccinated once with the same vaccine/adjuvant combination were partially protected against infection with a heterologous virus derived from clade 2.1 of H5N1 influenza viruses. Thus, the use of the novel adjuvant CoVaccine HT with cell culture-derived inactivated influenza A/H5N1 virus antigen is a promising and dose-sparing vaccine approach warranting further clinical evaluation.

Ability of SPI2 mutant of S. typhi to effectively induce antibody responses to the mucosal antigen enterotoxigenic E. coli heat labile toxin B subunit after oral delivery to humans

We have evaluated an oral vaccine based on an Salmonella enteric serovar typhi (S. typhi) Ty2 derivative TSB7 harboring deletion mutations in ssaV (SPI-2) and aroC together with a chromosomally integrated copy of eltB encoding the B subunit of enterotoxigenic Escherichia coli heat labile toxin (LT-B) in volunteers. Two oral doses of 10(8) or 10(9)CFU were administered to two groups of volunteers and both doses were well tolerated, with no vaccinemia, and only transient stool shedding. Immune responses to LT-B and S. typhi lipopolysaccharide were demonstrated in 67 and 97% of subjects, respectively, without evidence of anti-carrier immunity preventing boosting of LT-B responses in many cases. Further development of this salmonella-based (spi-VEC) system for oral delivery of heterologous antigens appears warranted.

Smooth pursuit eye-tracking impairment in childhood-onset psychotic disorders

OBJECTIVE

Although childhood-onset schizophrenia is relatively rare, a sizable group of children with severe emotional disturbances have transient psychotic symptoms that fall outside of current syndrome boundaries. The relationship of this group of children to those with childhood-onset schizophrenia and other childhood psychiatric disorders is unclear. In this study, the authors compared smooth pursuit eye tracking, a biological trait marker associated with schizophrenia, of children and adolescents with psychotic disorder not otherwise specified to that of children with childhood-onset schizophrenia and healthy comparison subjects.

METHOD

By means of infrared oculography, smooth pursuit eye movements during a 17 degrees /second visual pursuit task were quantitatively and qualitatively compared in 55 young adolescents (29 with childhood-onset schizophrenia and 26 with psychotic disorder not otherwise specified) and their respective independent healthy comparison groups (a total of 38 healthy subjects).

RESULTS

Subjects with childhood-onset schizophrenia had qualitatively poorer eye tracking, higher root mean square error, lower gain, and a greater frequency of catch-up saccades than healthy children. Subjects with psychotic disorder not otherwise specified also had qualitatively poorer eye tracking, higher root mean square error, and lower gain than healthy children, but saccade frequency did not differ significantly.

CONCLUSIONS

Children with childhood-onset schizophrenia exhibit a pattern of eye-tracking dysfunction similar to that reported for adult patients. Similar abnormalities were seen in the subjects with psychotic disorder not otherwise specified except that they did not exhibit a greater frequency of catch-up saccades. Prospective longitudinal neurobiological and clinical follow-up studies of both groups are currently underway to further validate the distinction between these two disorders. Also, family studies are planned to establish whether eye-tracking dysfunction represents a trait- or state-related phenomenon in subjects with psychotic disorder not otherwise specified.

Evaluation of a tetrazolium salt test to determine absence of live mycobacteria in tuberculin purified protein derivative

Current methodology to determine absence of live mycobacteria in tuberculin purified protein derivative (PPD) takes up to 8 weeks to perform and may also involve testing on animals. In this paper we describe an in vitro test utilising the tetrazolium salt, 2,3-bis-(2-methoxy-4-nitro-5-sulphenyl)-(2H)-tetrazolium-5-carboxanilide (XTT) to monitor the absence of live Mycobacterium tuberculosis (Mtb) in PPD. In the presence of live cells XTT is converted to a coloured formazan product that can be measured spectrophotometrically. Live mycobacteria present in spiked PPD were detected by a marked change in optical density above background levels. This test is easy to perform and is complete in just 48 hr.

Identification of substrains of BCG vaccine using multiplex PCR

Current methods for determining the identity of substrains of Mycobacterium bovis BCG (BCG) vaccine are labour intensive, or provide only limited substrain differentiation. In this paper we describe a multiplex PCR that distinguishes between M. tuberculosis (TB) and M. bovis and the non-pathogenic BCG strain, and also subdivides the BCG vaccine substrains investigated into seven distinct fingerprints based on six target regions in the DNA. This test is specific, rapid, reproducible and portable and is proposed as a novel test for BCG vaccine control. It offers substantial advantages over the methods currently in use. Using this test we have characterised a number of commercial BCG vaccines.

An open trial of plasma exchange in childhood-onset obsessive-compulsive disorder without poststreptococcal exacerbations

Patients with childhood-onset obsessive-compulsive disorder (OCD) with symptom exacerbations following streptococcal infections benefit from treatment with plasma exchange. In this study, 5 patients with treatment-refractory OCD without a history of streptococcus-related exacerbations underwent an open 2-week course of therapeutic plasma exchange. Behavioral ratings, completed at baseline and 4 weeks after the initial treatment, included the Clinical Global Impressions Scale and the Yale-Brown Obsessive Compulsive Scale. All 5 patients completed the trial with few side effects, but none showed significant improvement. Plasma exchange does not benefit children and adolescents with OCD who do not have streptococcus-related exacerbations.

Childhood-onset psychotic disorders: magnetic resonance imaging of volumetric differences in brain structure

OBJECTIVE

Although childhood-onset schizophrenia is rare, children with brief psychotic symptoms and prominent emotional disturbances commonly present diagnostic and treatment problems. Quantitative anatomic brain magnetic resonance images (MRIs) of a subgroup of children with psychotic disorder not otherwise specified were compared with those of children with childhood-onset schizophrenia and healthy comparison subjects.

METHOD

Anatomic MRIs were obtained for 71 patients (44 with childhood-onset schizophrenia and 27 with psychotic disorder not otherwise specified) and 106 healthy volunteers. Most patients had been treated with neuroleptics. Volumetric measurements for the cerebrum, anterior frontal region, lateral ventricles, corpus callosum, caudate, putamen, globus pallidus, and midsagittal thalamic area were obtained.

RESULTS

Patients had a smaller total cerebral volume than healthy comparison subjects. Analysis of covariance for total cerebral volume and age found that lateral ventricles were larger in both patient groups than in healthy comparison subjects and that schizophrenia patients had a smaller midsagittal thalamic area than both subjects with psychotic disorder not otherwise specified and healthy comparison subjects.

CONCLUSIONS

Pediatric patients with psychotic disorder not otherwise specified showed a pattern of brain volumes similar to those found in childhood-onset schizophrenia. Neither group showed a decrease in volumes of temporal lobe structures. Prospective longitudinal magnetic resonance imaging and clinical follow-up studies of both groups are currently underway to further validate the distinction between these two disorders.

Premorbid speech and language impairments in childhood-onset schizophrenia: association with risk factors

OBJECTIVE

As both premorbid neurodevelopmental impairments and familial risk factors for schizophrenia are prominent in childhood-onset cases (with onset of psychosis by age 12), their relationship was examined.

METHOD

Premorbid language, motor, and social impairments were assessed in a cohort of 49 patients with childhood-onset schizophrenia. Familial loading for schizophrenia spectrum disorders, familial eye-tracking dysfunction, and obstetrical complications were assessed without knowledge of premorbid abnormalities and were compared in the patients with and without developmental impairments.

RESULTS

Over one-half of the patients in this group had developmental dysfunction in each domain assessed. The patients with premorbid speech and language impairments had higher familial loading scores for schizophrenia spectrum disorders and more obstetrical complications, and their relatives had worse smooth-pursuit eye movements. The boys had more premorbid motor abnormalities, but early language and social impairments did not differ significantly between genders. There were no other significant relationships between premorbid social or motor abnormalities and the risk factors assessed here.

CONCLUSIONS

Premorbid developmental impairments are common in childhood-onset schizophrenia. The rates of three risk factors for schizophrenia (familial loading for schizophrenia spectrum disorders, familial eye-tracking dysfunction, and obstetrical complications) were increased for the probands with premorbid speech and language impairments, suggesting that the pathophysiology of schizophrenia involves the abnormal development of language-related brain regions.

Neuropsychological deficits in pediatric patients with childhood-onset schizophrenia and psychotic disorder not otherwise specified

OBJECTIVE

Children with transient psychotic symptoms and serious emotional disturbances who do not meet current criteria for schizophrenia or other presently recognized diagnostic categories commonly present diagnostic and treatment problems. Clarifying the connections between children with narrowly defined schizophrenia and children with a more broadly defined phenotype (i.e., Psychotic Disorder Not Otherwise Specified, PD-NOS) has implications for understanding the pathophysiology of schizophrenia. In this study, the neuropsychological test performance of a subgroup of children with atypical psychosis was compared with that of patients with childhood-onset schizophrenia (COS).

METHOD

Cognitive function was assessed with neuropsychological test battery regimens in 51 neuroleptic-nonresponsive patients within the first 270 at NIMH testing (24 PD-NOS, 27 COS) were included in this analysis. Seventeen (39%) of 44 COS subjects were unavailable for this study as their IQ tested <70. The PD-NOS patients were younger than the COS patients at the time of testing (12.0+/-2.8 vs 14.4+/-1.8years, respectively, p<0.004). The test levels of these groups were compared with each other.

RESULTS

The neuropsychological test results for the PD-NOS and COS patients were 1-2standard deviations below normative data across a broad array of cognitive functions. There were no overall differences in the test levels for the six summary scales (F=2.82, df=1, 36, p=0.10) or in the profile shape (F=1.70, df=5, 180, p=0.14) between the PD-NOS and COS groups. For the COS patients, there was a significant difference between their mean full-scale WISC IQ (84.7+/-16.2) and their average standard scores for both the spelling (97.7+/-16.1, n=23, t=4.0, p=0.001) and reading decoding subtests (97.7+/-13.7, n=23, t=3.7, p=0.001) of the Kaufman Test of Educational Achievement.

CONCLUSIONS

Treatment-refractory PD-NOS and COS patients share a similar pattern of generalized cognitive deficits, including deficits in attention, learning and abstraction which are commonly observed in adult patients with schizophrenia. These data support a hypothesis that at least some of the PD-NOS cases belong within the schizophrenic spectrum, which is of importance for future genetic studies planned for this cohort.

Lessons from childhood-onset schizophrenia

Childhood-onset schizophrenia (with an onset of psychosis by age 12) is a rare and severe form of the disorder which is clinically and neurobiologically continuous with the adult-onset disorder. Very early onset diseases provide an opportunity to look for more salient or striking risk or etiologic factors in a possibly more homogenous patient population. For the 47 patients with very early onset schizophrenia studied to date, there were more severe premorbid neurodevelopmental abnormalities, more cytogenetic anomalies, and potentially greater family histories of schizophrenia and associated spectrum disorders than later onset cases. There was no evidence for relatively increased obstetrical complications or environmental stress. These data, while preliminary, suggest a very early age of onset of schizophrenia may be secondary to greater genetic vulnerability. It is anticipated that future genetic studies of these patients may provide important etiologic information.

Elevated prolactin in pediatric patients on typical and atypical antipsychotics

As part of systematic treatment trials of haloperidol, clozapine, and olanzapine with a total of 35 children and adolescents with early onset psychosis, prolactin was measured at baseline and week 6 of treatment. The National Institute of Mental Health patients--13 females, 22 males (mean age, 14.1+/-2.3 years; range, 9.1-19 years) with childhood onset schizophrenia (n = 32), or Psychotic Disorder not otherwise specified (NOS) (n = 3) with onset of psychosis before age 13--were recruited for open or double-blind trials of haloperidol, clozapine, or olanzapine. Baseline serum prolactin was measured after a 3-week washout period and after 6 weeks of treatment. Mean prolactin concentration after 6 weeks of treatment was significantly elevated on all three drugs; however, on clozapine, mean prolactin remained within the normal range. Prolactin was increased above the upper limit of normal for 100% of 10 patients on haloperidol, 70% of 10 patients on olanzapine, and 0% of 15 patients on clozapine (chi2 analyses: H > C, p = 0.004; O > C, p = 0.001). Given the potential endocrine and possible cardiac correlates of hyperprolactinemia, these more robust prolactin elevations in pediatric patients after short-term exposure to olanzapine than those reported for adults justify longer observation intervals with bigger samples to establish treatment safety of atypical antipsychotics in adolescents.

Obstetrical complications and childhood-onset schizophrenia

OBJECTIVE

Increased obstetrical complications have been reported in individuals with adult-onset schizophrenia, with several studies finding an association between such complications and an earlier age at onset. Consequently, obstetrical records were examined for individuals with childhood-onset schizophrenia to determine if birth complications were more prevalent.

METHOD

The birth records of 36 patients with childhood-onset schizophrenia and 35 sibling comparison subjects were rated for birth complications by two psychiatrists who were unaware of group membership.

RESULTS

There were no significant differences between the groups in rates of obstetrical complications. Patients with such complications did not have a relatively earlier age at onset of schizophrenia.

CONCLUSIONS

A very early age at onset of schizophrenia is probably not due to birth complications.

Childhood-onset schizophrenia: progressive brain changes during adolescence

BACKGROUND

Previous NIMH childhood onset schizophrenia (COS) anatomic brain MRI studies found progression of ventricular volume and other structural brain anomalies at 2-year follow up across mean ages 14 to 16 years. However, studies in adult patients generally do not show progression of ventricular volume or correlation of ventricular volume with duration of illness. To address issues of progression of brain anomalies in schizophrenia, this report extends previous studies to include a third longitudinal scan, uses a larger sample size, and includes measures of the amygdala and hippocampus.

METHODS

Volumes of the total cerebrum, lateral ventricles, hippocampus, and amygdala were quantified on 208 brain magnetic resonance imaging scans from 42 adolescents with COS (23 with one or more repeat scan) and 74 age- and gender-matched controls (36 with one or more repeat scan). A statistical technique permitting combined use of cross-sectional and longitudinal data was used to assess age-related changes, linearity, and diagnostic group differences.

RESULTS

Differential nonlinear progression of brain anomalies was seen during adolescence with the total cerebrum and hippocampus decreasing and lateral ventricles increasing in the COS group. The developmental curves for these structures reached an asymptote by early adulthood for the COS group and did not significantly change with age in the control group.

CONCLUSIONS

These findings reconcile less striking progression of anatomic brain images usually seen for adult schizophrenia and complement other data consistent with time-limited, diagnostic-specific decreases in brain tissue. Adolescence appears to be a unique period of differential brain development in schizophrenia.

Clinical and neurobiological correlates of cytogenetic abnormalities in childhood-onset schizophrenia

OBJECTIVE

Cytogenetic abnormalities are increased in schizophrenia, suggesting a possible etiologic contribution. However, their clinical and pathophysiologic roles in the disorder are unknown. To investigate this, a group of children and adolescents participating in a comprehensive study of childhood-onset schizophrenia were screened for chromosomal abnormalities, and their clinical and neurobiological correlates were examined.

METHOD

Cytogenetic screening with the use of high-resolution banding, fluorescent in situ hybridization for chromosome 22q11 deletions, and molecular fragile X testing was undertaken in a group of 47 children and adolescents with very early onset of schizophrenia. Clinical, neurobiological (including brain morphometry), and risk factor measures of the subjects with cytogenetic abnormalities were compared with those of the remaining patients without cytogenetic anomalies.

RESULTS

Five patients had previously undiagnosed cytogenetic abnormalities. Lower performance IQ and more pronounced premorbid developmental impairments were seen in this subgroup. Rates of obstetric complications, familial schizophrenia spectrum disorders, and familial eye tracking dysfunction were similar for the patients with and without cytogenetic abnormalities.

CONCLUSIONS

Cytogenetic abnormalities appear to be increased in childhood-onset schizophrenia, suggesting an association with a very early age at onset. The data from the subgroup of patients with cytogenetic anomalies are consistent with a model in which a childhood onset of schizophrenia is due to a greater impairment of neurodevelopment secondary to the interaction of a number of factors, particularly genetic ones.

Including children and adolescents with schizophrenia in medication-free research

OBJECTIVE

There has been an increasing focus on the ethical issues raised by studies requiring the withdrawal of effective medication in schizophrenic adults. This article examines the risks and benefits of a medication-free period for pediatric patients with treatment-refractory schizophrenia who are participating in an ongoing study.

METHOD

Between April 1993 and March 1998, 31 children and adolescents were admitted with a diagnosis of treatment-resistant, childhood-onset schizophrenia. Parental consent was obtained so that patients could participate in a medication-free research period. Patients were evaluated at screening, at the end of a 4-week washout, at the completion of a 6- to 8-week atypical neuroleptic trial, and at a 2- to 4-year follow-up.

RESULTS

At the completion of a 4-week drug-free period, seven patients (23%) were diagnosed with another disorder on the basis of data gained from the drug-free period and their lack of schizophrenic symptoms. Their revised diagnoses were posttraumatic stress disorder (N = 1), an atypical psychosis labeled "multidimensionally impaired" (N = 4), and personality disorder (N = 2). At follow-up, three of these patients remained free of neuroleptic therapy. For eight patients (26%), the washout was curtailed because of rapid and severe deterioration of their schizophrenic symptoms.

CONCLUSIONS

For children and adolescents with treatment-refractory schizophrenia, a medication-free period can be conducted safely for at least 4 weeks for inpatients. Such trials are useful on clinical grounds and for providing homogeneous patient groups for research. This study also highlights the necessity of having access to hospitalization to observe children and adolescents with psychotic symptoms while medication free.

Progressive cortical change during adolescence in childhood-onset schizophrenia. A longitudinal magnetic resonance imaging study

BACKGROUND

Adolescence provides a window to examine regional and disease-specific late abnormal brain development in schizophrenia. Because previous data showed progressive brain ventricular enlargement for a group of adolescents with childhood-onset schizophrenia at 2-year follow-up, with no significant changes for healthy controls, we hypothesized that there would be a progressive decrease in volume in other brain tissue in these patients during adolescence.

METHODS

To examine cortical change, we used anatomical brain magnetic resonance imaging scans for 15 patients with childhood-onset schizophrenia (defined as onset of psychosis by age 12 years) and 34 temporally yoked, healthy adolescents at a mean (SD) age of 13.17 (2.73) years at initial baseline scan and 17.46 (2.96) years at follow-up scan. Cortical gray and white matter volumes were obtained with an automated analysis system that classifies brain tissue into gray matter, white matter, and cerebrospinal fluid and separates the cortex into anatomically defined lobar regions.

RESULTS

A significant decrease in cortical gray matter volume was seen for healthy controls in the frontal (2.6%) and parietal (4.1%) regions. For the childhood-onset schizophrenia group, there was a decrease in volume in these regions (10.9% and 8.5%, respectively) as well as a 7% decrease in volume in the temporal gray matter. Thus, the childhood-onset schizophrenia group showed a distinctive disease-specific pattern (multivariate analysis of variance for change X region X diagnosis: F, 3.68; P = .004), with the frontal and temporal regions showing the greatest between-group differences. Changes in white matter volume did not differ significantly between the 2 groups.

CONCLUSIONS

Patients with very early-onset schizophrenia had both a 4-fold greater decrease in cortical gray matter volume during adolescence and a disease-specific pattern of change. Etiologic models for these patients' illness, which seem clinically and neurobiologically continuous with later-onset schizophrenia, must take into account both early and late disruptions of brain development.

Development of a tetrazolium salt assay for rapid determination of viability of BCG vaccines

Standardisation and control of the live Mycobacterium bovis BCG (BCG) vaccine is performed as specified by the World Health Organisation (WHO) and the European Pharmacopoeia (EP). The conventional viable count for control of potency of BCG vaccine is performed by culturing on solid medium. This assay method is not only time consuming but may give variable results. A tetrazolium salt assay has been developed and evaluated as a potential additional, or replacement, test for determining number of viable organisms. The tetrazolium salts 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and 2,3-bis-(2-methoxy-4-nitro-5-sulphenyl)-(2H)-tetrazolium-5-carb oxanilide (XTT) used as alternative substrates in the assay both gave more rapid and reproducible results than the conventional viable count. XTT showed greater sensitivity than MTT with a lower detection limit of about 7x10(4) colony forming units (c.f.u.) ml(-1). The XTT assay has proven effective for determining viability of suspensions prepared from several BCG vaccine substrains, covering a range of viable units, without the need for modification. This assay is easily performed and takes just 48 h to produce an estimate of viable cell content compared with 3 weeks for the conventional method.

Childhood-onset schizophrenia: an open-label study of olanzapine in adolescents

OBJECTIVE

Olanzapine, a potent 5-HT2a/2c, dopamine D1D2D4 antagonist with anticholinergic activity, has a profile of known receptor affinity similar to that of clozapine. This pilot study examined the efficacy of olanzapine for treatment-refractory childhood-onset schizophrenia in eight patients who had received 8-week open-label trials. For comparison, data are included from 15 patients who had received 6-week open-label clozapine trials using identical rating instruments (largely by the same raters) in the same treatment setting.

METHOD

Twenty-three children and adolescents with an onset of DSM-III-R schizophrenia by age 12 for whom at least two different typical neuroleptics had been ineffective participated in the two separate studies. Some of the patients were intolerant of clozapine, although it had been effective (n = 4). Patients receiving olanzapine were evaluated over 8 weeks with the Brief Psychiatric Rating Scale (BPRS), the Scale for the Assessment of Positive Symptoms, the Scale for the Assessment of Negative Symptoms, and the Clinical Global Impressions Scale for Improvement.

RESULTS

For the eight patients who received olanzapine trials, at week 8 there was a 17% improvement in the BPRS total score, a 27% improvement in the Scale for the Assessment of Negative Symptoms, and a 1% improvement in the Scale for the Assessment of Positive Symptoms, relative to "ideal" admission status on typical neuroleptics. In contrast, the magnitude of the effect sizes for each of the clinical ratings was larger at week 6 of the previous clozapine trial than for an 8-week olanzapine trial, relative to admission status on typical neuroleptics. For the four children who had received both clozapine and olanzapine, BPRS total scores were significantly lower at week 6 of clozapine treatment compared with week 6 of olanzapine treatment (p = .03).

CONCLUSION

These data provide preliminary evidence for the efficacy of olanzapine for some children and adolescents with treatment-refractory schizophrenia, but they also suggest the need for a more rigorous double-blind comparison of these two atypical antipsychotics.

Brief report: association of sex chromosome anomalies with childhood-onset psychotic disorders

OBJECTIVE

An apparent excess of sex chromosome aneuploidies (XXY, XXX, and possibly XYY) has been reported in patients with adult-onset schizophrenia and with unspecified psychoses. This study describes the results of cytogenetic screening carried out for pediatric patients meeting DMS-III-R criteria for childhood-onset schizophrenia (COS) and a subgroup of patients with childhood-onset psychotic disorder not otherwise specified, provisionally labeled by the authors as multidimensionally impaired (MDI).

METHOD

From August 1990 to July 1997, karyotypes were determined for 66 neuroleptic-nonresponsive pediatric patients (28 MDI, 38 COS), referred to the National Institute of Mental Health for an inpatient treatment trial of clozapine.

RESULTS

Four (6.1%) of 66 patients (3 MDI, 1 COS) were found to have sex chromosome anomalies (mosaic 47,XXY; 47,XXY; 47,XYY; mosaic 45,XO, respectively), which is higher than the expected rate of 1 per 426 children or 2.34 per 1,000 in the general population (4/66 versus 1/426, chi 2 = 19.2, df = 1, p = .00001). All cases had been previously undiagnosed.

CONCLUSIONS

These findings lend support to a hypothesis that a loss of balance of gene products on the sex chromosomes may predispose affected individuals to susceptibility to additional genetic and environmental insults that result in childhood-onset psychotic disorders. Karyotyping of children with psychotic disorders should be routine.

The killing of Helicobacter pylori by low-power laser light in the presence of a photosensitiser

Helicobacter pylori is associated with various gastrointestinal disorders. Lethal photosensitisation was investigated as a possible technique for killing H. pylori which might offer a better alternative to antibiotics. The susceptibility of H. pylori to lethal photosensitisation was determined by mixing suspensions of H. pylori with various photosensitisers and plating out on blood agar before irradiation with low-power laser light. Five sensitisers were studied further by mixing them with H. pylori in a tissue-culture plate and counting survivors after irradiation as a function of laser exposure time, dye concentration and pre-irradiation time. Crystal violet and thionine were ineffective as sensitisers, but zones of inhibition appeared with methylene blue (MB), protoporphyrin IX (PPIX), haematoporphyrin derivative (HPD), toluidine blue O (TBO) and disulphonated aluminium phthalocyanine (S2). Laser light or sensitiser alone did not affect bacterial viability. S2 (100 microg/ml) with a laser light energy density of 16 J/cm2, HPD (10O microg/ml) with 160 J/cm2, MB (100 microg/ml) with 21 J/cm2, PPIX (150 microg/ml) with 320 J/cm2 and TBO (50 microg/ml) with 160 J/cm2 all reduced bacterial viability by >99%. The killing of sensitised H. pylori by laser light offers a new approach to the treatment of localised infections when all colonised areas are accessible to light.

Photodynamic therapy using 5-aminolaevulinic acid for experimental pancreatic cancer--prolonged animal survival

Experimental studies have been carried out using 5-aminolaevulinic acid (ALA) to induce transient porphyrin photosensitisation for photodynamic therapy (PDT) in a pancreatic cancer model in Syrian golden hamsters. ALA was given either intravenously or orally (in bolus or fractionated doses) with the laser light delivered by means of a bare fibre touching the tissue surface or external irradiation using a light-integrating cylindrical applicator. Animals were killed 1-24 h after ALA administration for pharmacokinetic studies and 3-7 days after light exposure to study PDT-induced necrosis. A separate survival study was also performed after a fractionated oral dose of ALA and external irradiation. Protoporphyrin IX sensitisation in the tumour tissue as measured by quantitative fluorescence microscopy was highest after intravenous administration of 200 mg kg-1 ALA and then in decreasing order after oral fractionated and oral bolus doses (both 400 mg kg-1). Laser light application at 630 nm to give 12-50 J from the bare fibre or 50 J cm-2 using surface illumination with the cylindrical applicator resulted in tumour necrosis up to 8 mm in depth. In larger tumours a rim of viable tumour was observed on the side opposite to illumination. In a randomised study, survival of treated animals was significantly longer than in the untreated control group (log-rank test, P < 0.02), although all animals died of recurrent tumour. This technique shows promise in the treatment of small volumes of tumour in the pancreas.

Endogenous porphyrin distribution induced by 5-aminolaevulinic acid in the tissue layers of the gastrointestinal tract

The accumulation of endogenous porphyrins in rats following systemic administration of 5-aminolaevulinic acid (ALA) has been examined to assess the photosensitization characteristics of this technique for photodynamic therapy (PDT) and chemical extraction assays with fluorescence and absorbance detection of the porphyrin content have been carried out. We compared the results obtained using quantitative microfluorimetry on normal gastric and colonic tissues in rats at 0.5, 1, 2, 4 and 6 h and chemically induced duodenal tumours 2 and 4.5 h after intravenous administration of ALA at a dose of 200 mg kg-1. With chemical extraction followed by high performance liquid chromatography analysis, protoporphyrin IX (PpIX) was found to be the predominant porphyrin present, reaching peak levels of several microgrammes per gramme at 2-4 h in each type of tissue; a small amount of coproporphyrin was detected at 0.5 and 2 h in normal gastric mucosa and duodenal tumour respectively. Both the extraction assay and quantitative microfluorimetry showed that the porphyrin fluorescence builds up rapidly in the mucosal layers of the colon and stomach, reaching a maximum at 2 h, whereas lower fluorescence levels were found with a slower rate of accumulation in the corresponding muscularis layers. A significant PpIX content was found in the duodenal tumour, with a maximum of 7.1 micrograms g-1 4.5 h after ALA administration. We conclude that systemic administration of ALA can induce effective tissue sensitization with protoporphyrin IX and appears to be a promising technique for PDT.

Oral versus intravenous administration of 5-aminolaevulinic acid for photodynamic therapy

Endogenously synthesised protoporphyrin IX (PpIX) following the administration of 5-amino-laevulinic acid (ALA) is an effective photosensitiser for photodynamic therapy (PDT). Following intravenous administration, PpIX accumulates predominantly in mucosa of hollow viscera and on light exposure, mucosal ablation results with relative sparing of the submucosa and muscularis layers. Oral administration is effective with ALA in contrast to conventional exogenous photosensitisers such as haematoporphyrin derivative and phthalocyanines. Oral administration of ALA is also simpler, safer, cheaper and more acceptable to patients. We studied the porphyrin sensitisation kinetics profile in the stomach, colon and bladder in normal rats following enterally and parenterally administered ALA using microscopic fluorescence photometric studies of frozen tissue sections. Mucosal cells in all three organs exhibit higher fluorescence levels as compared with underlying smooth muscle following both intravenous and oral administration. Peak concentration were seen 4 h after sensitisation at the highest doses used (200 mg kg-1 i.v., 400 mg kg-1 oral), and slightly earlier with lower doses. The temporal kinetics of both routes of administration were similar although a higher oral dose was required to achieve the same tissue concentration of PpIX. The highest level of fluorescence was achieved in the gastric mucosa and in decreasing levels, colonic and bladder mucosa. A similar degree of mucosal selectivity was achieved in each organ with each route of administration but an oral dose in excess of 40 mg kg-1 was required to achieve measurable PpIX sensitisation. In a pilot clinical study, two patients with inoperable rectal adenocarcinomas were given 30 mg kg-1 and one patient with sigmoid colon carcinoma was given 60 mg kg-1 ALA orally. Serial biopsies of normal and tumour areas were taken over the subsequent 24 h. Fluorescence microscopy of these specimens showed maximum accumulation of PpIX 4 to 6 h after administration of 30 mg kg-1 ALA. There was greater PpIX accumulation in tumour than adjacent normal mucosa in two patients. Preferential PpIX accumulation in tumour was greater in the patient receiving 60 mg kg-1 ALA.

Experimental studies to assess the potential of photodynamic therapy for the treatment of bronchial carcinomas

BACKGROUND

Photodynamic therapy (PDT) is a technique for producing localised tissue necrosis with light after prior administration of a photosensitising drug. There is some selectivity of uptake of photosensitisers in malignant tissue, although this is difficult to exploit. Full thickness necrosis in normal and neoplastic colon heals without perforation because of a lack of effect on collagen, making local cure a possibility. The experiments described here aim to establish whether these conclusions are also valid for bronchial tumours.

METHODS

In pharmacokinetic studies normal rats were given 5 mg/kg of the photosensitiser aluminium sulphonated phthalocyanine (A1SPc) intravenously and killed up to one month later. The distribution of A1SPc in the trachea was measured by chemical extraction and fluorescence microscopy. In subsequent experiments sensitised animals were treated with light delivered to the tracheal mucosa through a thin flexible fibre and the resultant lesions were studied for their size, mechanical strength, and healing. A series of resected human bronchial carcinomas were examined histologically for their collagen content.

RESULTS

The tracheal concentration of A1SPc in normal rats was maximum 1-20 hours after administration. Fluorescence microscopy revealed that most was in the perichondrium and submucosal stroma, with little in the cartilage. Light exposure showed necrosis of the soft tissues which healed by regeneration, but no effect on cartilage and no reduction in the mechanical strength of the trachea at any stage. Histological examination of resected human bronchial carcinomas showed more collagen in the tumour areas than would be found in normal regions.

CONCLUSIONS

PDT leads to necrosis of the soft tissues of the normal trachea but there is complete healing by regeneration, no risk of perforation (due to collagen preservation), and no effect on cartilage. Human bronchial carcinomas apparently contain more collagen than normal bronchi which may give protection against perforation following necrosis induced by PDT. PDT may have a role in eradicating small volumes of tumour tissue in situ and could be valuable for treating (1) small carcinomas in patients unfit for resection, (2) tumour remaining after surgical resection, (3) stump recurrences, or (4) to prolong palliation of tumours after debulking with the NdYAG laser.

Increasing the effect of photodynamic therapy on the RIF-1 murine sarcoma, using the bioreductive drugs RSU1069 and RB6145

The effect of combining photodynamic therapy (PDT) and bioreductive drugs has been investigated using the RIF-1 experimental murine tumour. Light was delivered interstially to the tumour at 675 nm using a single optical fibre attached to an argon-ion dye laser. The photosensitizer was disulphonated aluminium phthalocyanine (AlS2Pc) and the bioreductive drugs were the dual function nitroimidazole RSU1069 and its pro-drug RB6145. Varying the time between administration of the photosensitizer and light delivery (TL) from 30 min to 24 h had little influence on the extent of the anti-tumour effect of PDT alone, as measured by the regrowth delay endpoint. When the bioreductive drug was included in the treatment, administered 20 min before light irradiation, regrowth delay was greatly increased. The effectiveness of the combined treatment was optimum for short values of TL (about 1 h). Fluorescence microscopy was used to investigate the distribution of the photosensitizer within the tumours. This showed that the compound was mainly confined to the tumour vasculature over the first few hours post-treatment. The high efficacy of the combined treatment of PDT and bioreductive drugs for short values of TL suggest that photodynamic action, during the period when the photosensitizer AlS2Pc is confined to the vasculature, enhances the severity of tumour hypoxia which is sufficient to induce activation of the bioreductive drugs.

Photodynamic therapy of the normal rat stomach: a comparative study between di-sulphonated aluminium phthalocyanine and 5-aminolaevulinic acid

Dysplasia in the upper gastrointestinal tract carries a risk of invasive malignant change. Surgical excision of the affected organ is the only treatment available. Photodynamic therapy has been shown to be promising in the treatment of early and superficial tumours and may be useful for the ablation of dysplastic mucosa. Because of the diffuse nature of the disease, such treatment would necessarily involve destruction of large areas of mucosa and it is desirable to confine its effect to the mucosa in order that safe healing can take place. By means of photometric fluorescence microscopy, we have studied the pattern of photosensitisation in the normal rat stomach using di-sulphonated aluminium phthalocyanine (AlS2Pc) and 5-aminolaevulinic acid (ALA) as photosensitisizers. AlS2Pc resulted in a panmural photosensitisation of the gastric wall with the highest level encountered in the submucosa. The mucosa and muscularis propria were sensitised to equal extent. Following light exposure, a full thickness damage resulted. ALA is a natural porphyrin precursor and exogenous administration gave rise to accumulation of protoporphyrin IX (PPIX) in the cells. The resultant pattern of photosensitisation was predominantly mucosal and its photodynamic effect was essentially confined to the mucosa. ALA produced a selective photosensitisation of the gastric mucosa for its photodynamic ablation with sparing the underlying tissue layers.

Selective necrosis in hamster pancreatic tumours using photodynamic therapy with phthalocyanine photosensitization

Photodynamic therapy (PDT) is often thought to be able to effect selective tumour necrosis. This therapeutic selectivity, based on transient differences in tumour: normal tissue photosensitizer concentration ratios, is rarely useful clinically in extracranial tumours, although PDT itself may be of value by virtue of the nature of the damage produced and healing of normal tissue by regeneration. This report describes the effects of PDT on normal pancreas and chemically induced pancreatic cancers in the hamster, where a different mechanism of selective necrosis may be seen. Photosensitizer distribution in normal and neoplastic pancreas was studied by chemical extraction and fluorescence microscopy. Correlation of distribution studies with necrosis produced by PDT shows that the photodynamic dose (product of tissue concentration of sensitizer and light dose) threshold for damage is seven times as high for normal pancreas as for pancreatic cancer. Tumour necrosis extended to the point where tumour was invading normal areas without damaging the normal tissue. In rat colonic cancer, photodynamic dose thresholds in tumour and normal tissue are similar and so such marked selectivity of necrosis is not possible. The reason for this selectivity in the pancreas is not clear, but recent evidence has suggested a difference in response to PDT between normal and neoplastic pancreatic cell lines and the presence of a singlet oxygen scavenger in normal pancreas is postulated. Furthermore, the present fluorescence microscopy studies suggest that tumour stroma contains the highest level of photosensitizer and thus receives the highest photodynamic dose during PDT. These results suggest a possible role for PDT in treating small pancreatic tumours or as an adjuvant to other techniques, such as surgery, that reduce the main bulk of tumours localized to the pancreas.

Fluorescence distribution and photodynamic effect of ALA-induced PP IX in the DMH rat colonic tumour model

Aminolaevulinic acid (ALA) is the first committed step in haem synthesis. In the presence of excess ALA the natural regulatory feedback system is disrupted allowing accumulation of protoporphyrin IX (PP IX) the last intermediate product before haem, and an effective sensitiser. This method of endogenous photosensitisation of cells has been exploited for photodynamic therapy (PDT). We have studied the fluorescence distribution and biological effect of induced PP IX in normal and tumour tissue in the rat colon. Fluorescence in normal colonic tissue was at a peak of 4 h with a rapid fall off by 6 h. The fluorescence had returned to background levels by 24 h. All normal tissue layers followed the same fluorescence profile but the mucosa showed fluorescent levels six times higher than the submucosa, with muscle barely above background values. At 6 h the ratio of fluorescence levels between normal mucosa and viable tumour was approximately 1:6. At this time laser treatment showed necrosis of normal mucosa and tumour with sparing of normal muscle. There was good correlation between the fluorescence distribution and the biological effect of ALA-induced photosensitisation on exposure to red light. ALA may be superior to conventional sensitisers for tumours that produce haem as the PP IX is synthesised in malignant cells while the other sensitisers mainly localise to the vascular stroma of tumours. There is also a greater concentration difference between the PP IX levels in tumours and in normal mucosa and normal muscle than with the other photosensitisers raising the possibility of more selective necrosis in tumours.

Distribution and photodynamic effect of disulphonated aluminium phthalocyanine in the pancreas and adjacent tissues in the Syrian golden hamster

Necrosis of small volumes of tumour tissue with photodynamic therapy (PDT) can be achieved relatively easily. For this to be clinically relevant, it is essential to know what the same treatment parameters do to adjacent normal tissues into which the tumour has spread. For pancreatic cancers, local spread to vital structures is common. We have studied chemical extraction, microscopic fluorescence kinetics and photodynamic effects of disulphonated aluminum phthalocyanine (AlS2Pc) in normal pancreas and adjacent tissues in hamsters. Chemical extraction exhibited a peak duodenal concentration of AlS2Pc 48 h after sensitisation, with levels much higher than in stomach and pancreas. With microscopic fluorescence photometry highest levels were seen in duodenal submucosa and bile duct walls 48 h after photosensitisation. Pancreatic ducts, duodenal mucosa and gastric mucosa and submucosa exhibited intermediate fluorescence with relatively weak fluorescence in pancreatic acinar tissue and the muscle layer of the stomach. As expected, on the basis of fluorescence intensity and chemical extraction studies, the duodenal and bile duct wall were the most vulnerable tissues to photodynamic therapy. When the dose of 5 mumol kg-1 of sensitiser was used, duodenal perforations, gastric ulcers and transudation of bile from the bile duct occurred. However, the lesions in the stomach and bile duct healed without perforation or obstruction, so only the duodenum was at risk of serious, irreversible damage. Using a lower dose of photosensitiser markedly reduced damage.

Enhanced tumour selectivity of photodynamic therapy in the rat colon using a radioprotective agent

Radioprotective agents have been found to protect normal tissues during photodynamic therapy (PDT). We have investigated a phosphorylated thiol protectant WR-77913 (W7) with the photosensitizer aluminium sulphonated phthalocyanine (AISPc). We compared the effects of PDT on normal and tumour tissue in the rat colon, with and without this protectant. In normal colon no necrosis was seen in sites treated after administration of the W7. Necrosis of mean diameter 4.2 mm was seen in those given the protectant after light exposure. At tumour sites the area of necrosis was similar after light exposure before and after the administration of the protective agent. These results suggest a possible role for W7 in enhancement of selectivity of PDT action. Several mechanisms of protection against porphyrin phototoxicity by these drugs have been proposed, including acceleration of photobleaching. We used fluorescence to detect AISPc in strips of rat colon before and after laser treatment, with and without W7. However, a primary role for the photobleaching of AISPc as the mechanism for the protection shown is not supported by these observations.

Comparison of distribution and photodynamic effects of di- and tetra-sulphonated aluminium phthalocyanines in normal rat colon

We have previously reported photodynamic therapy of normal rat colon using aluminium sulphonated phthalocyanine (AISPc). In that study, the AISPc used was a mixture of phthalocyanines of different degrees of sulphonation. Phthalocyanines of defined degrees of sulphonation have recently become available and we compared the distribution of the di- and tetra-sulphonates (AIS2Pc and AIS4Pc) in rat colon and colon wall structures employing both chemical extraction and fluorescence photometry using a charge coupled device imaging system. Also, the photodynamic effects produced by these components in rat colon were compared at various times after photosensitization. After intravenous photosensitizer administration using equimolar doses, the concentration of AIS2Pc in colon fell off more rapidly with time than AIS4Pc. Differences were noted in the microscopic distribution of these compounds, with the di-sulphonate exhibiting peak fluorescence in colon wall structures by 1 h after photosensitization, while mucosal fluorescence with the tetra-sulphonate peaked at 5 h. Fluorescence was also lost from the colon wall much more slowly with the tetra-sulphonate, which tended to be retained in the submucosa. Maximum photosensitizing capability was seen at 1 h with AIS2Pc and no lesions could be produced with photodynamic therapy at 1 week, with up to 5.65 mumol/kg. With AIS4Pc (5.65 mumol/kg), while no lesions could be produced with light treatment at 1 h, photodynamic therapy at 1 week produced lesions only slightly smaller than those produced with treatment at 48 h (the time of maximum effect), and significant photosensitization was present at 2 weeks.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of sulfonation on the cell and tissue distribution of the photosensitizer aluminum phthalocyanine

Aluminum sulfonated phthalocyanine has potential as a suitable photosensitizer for use in the photodynamic therapy of cancer. In the present study, cellular uptake and retention of the individual mono-, di-, tri-, and tetrasulfonated derivatives (AlS1-4Pc) were examined in tissue culture and in normal and neoplastic tissue of tumor-bearing mice. Uptake and retention of the various derivatives by cells in tissue culture correlated inversely with the degree of sulfonation. Accordingly, Colo 26 cells in monolayer culture, 24 h after addition of 10 microM of appropriate photosensitizer, had accumulated approximately 25-fold more AlS1Pc than AlS3Pc and retained this species longer than more sulfonated derivatives. In contrast to these in vitro results, it was found that Colo 26 growing s.c. in BALB/c mice accumulated photosensitizer to a greater extent when the degree of sulfonation increased, such that A1S4Pc greater than AlS3Pc greater than AlS2Pc greater than AlS1Pc. By 24-48 h after the i.v. injection of 0.1 ml 2.27 mM solution of individual photosensitizer, the relative ratios of tumor:adjacent tissue varied from greater than 10:1 to greater than 2:1, showing that selective tumor uptake may be affected profoundly by the composition of the phthalocyanine compound. The livers and spleens of both normal and tumor-bearing mice, unlike other normal tissue, took up the sulfonated derivatives in an order that provided a mirror image of that observed in neoplastic tissue. These complex in vivo distribution and retention characteristics appear to be a consequence of relative hydrophilicity/hydrophobicity properties of the sulfonated species and indicate the extent to which these characteristics may influence photosensitizer distribution and accumulation.

Sexual dimorphism of erythropoietin-degrading activity in mouse submaxillary gland extracts

In the course of investigation of submaxillary gland (SG) extracts from mice as a possible source of extra-renal erythropoietin (EPO) we have extended our previous studies of the degradation of EPO added to SG and kidney extracts. The discrepancy between estimates of EPO obtained with two radioimmunoassays (RIAs) differing only in time of incubation with 125I-labeled recombinant human EPO (r-HuEPO) (20 h and 72 h) has been used as an indicator of tracer degradation occurring during the RIA incubation. Degradation of 125I-labeled r-HuEPO by male mouse SG extracts was not prevented by addition of inhibitors of monodeiodinases or proteolytic enzymes. Degradation of added 125I-labeled r-HuEPO was monitored using gel filtration fast protein liquid chromatography. SG extracts from male and androgen-treated female mice both degraded tracer r-HuEPO to a greater extent than extracts from female mice. Tracer degradation increased with time and tissue concentration and could give rise to invalid estimates of EPO in SG extracts by RIA. In contrast, none of the kidney extracts degraded r-HuEPO. Recovery of mouse serum EPO added to and incubated with male mouse SG or kidney extracts was 13% and 93%, respectively, estimated by RIA under conditions that excluded degradation of the RIA tracer antigen.