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Biomedical subjects

J A Griffin

Publications and source records attributed to J A Griffin.

At least 19 recordsLinked to original sources
PubMed2001

Treatment of meningeal breast cancer xenografts in the rat using an anti-p185/HER2 antibody.

The metastatic spread of breast cancer to the leptomeninges (LM) is a painful, debilitating, and usually lethal condition. Current therapies are generally ineffective or extremely toxic. The current study evaluated monoclonal antibody therapy in an animal model of LM human breast cancer. Monoclonal antibody 4D5, which recognizes the extracellular domain of the HER2/neu receptor, was administered into the cerebrospinal fluid of athymic rats implanted with human breast cancer cell lines. Continuous intraventricular administration of 4D5 inhibited growth of SKBR3 cells that overexpress HER2/neu but not of MCF7 cells, which do not. Inhibition was dose-dependent, with higher doses of 4D5 producing an improved response. i.p. administration of cisplatin in addition to 4D5 did not improve results. Continuous administration of 4D5 into the lumbar, as opposed to the ventricular intrathecal space, was not therapeutically effective. Treatment with 4D5 did not result in outgrowth of cells lacking expression of the HER2/neu receptor. These results suggest that 4D5, administered regionally, may palliate LM metastases from HER2/neu-overexpressing breast carcinoma.

Animals↗
PubMed2000

Comparison of in vitro antibody-targeted cytotoxicity using mouse, rat and human effectors.

Antibodies can direct tumor cell lysis by activating complement-mediated and cell-mediated cytoxicities (antibody-dependent cell-mediated cytotoxicity, ADCC). Clinical translation of these effects into successful cancer therapy has been slow. Choosing an appropriate animal model to test new therapeutic strategies is difficult because of species differences in immunological effector functions. In previous work, we found that an unmodified anti-ganglioside mouse IgG3 monoclonal antibody (mAb), 3F8, could successfully treat clinical tumors in humans and experimental tumors in rats but not experimental tumors in mice. We explored the reasons for this species difference by performing in vitro antibody-dependent cytotoxicity assays comparing the potency of polymorphonuclear neutrophils (PMN), natural killer (NK) cells and complement from the three species: mouse, rat and human. 3F8-dependent complement-mediated cytotoxicity produced more than 70% specific release when human and rat sera were used and only 20% with mouse serum. PMN-mediated ADCC was 35%-70% with human effectors, 25%-60% with rat and undetectable with mouse. Human eosinophils did not contribute to this ADCC. Cytotoxicity utilizing interleukin-2-activated NK cells was antibody-independent in all three species but the specific release was 60%-70% with human and rat NK cells and 10% with mouse NK cells. These data suggest that, for mouse IgG3, the rat may provide a more relevant rodent model than the mouse for testing the in vivo antitumor effects of monoclonal antibodies.

Animals↗
PubMed1999

Treatment of neoplastic meningeal xenografts by intraventricular administration of an antiganglioside monoclonal antibody, 3F8.

Leptomeningeal (LM) neoplastic metastases are painful, debilitating and inevitably lethal. Intrathecal (IT) anti-tumor antibodies may have therapeutic potential. We evaluated 3F8, an anti-G(D2) murine IgG(3) monoclonal antibody (MAb) in the treatment of human melanoma (SKMEL-1) and neuroblastoma (NMB7) xenografts in athymic rats. Both tumors were lysed efficiently in vitro by 3F8 in the presence of rat neutrophils or rat complement. Antibody-dependent cellular cytotoxicity (ADCC) was not augmented by recombinant human GM-CSF (rhGM-CSF), rhG-CSF, recombinant rat MIP-2 (rrMIP-2) or lipopolysaccharide (LPS). In vivo, continuous intraventricular administration of 3F8 and LPS prevented tumor engraftment, retarded tumor growth and eradicated 3-day-old established xenografts whereas 3F8 alone, LPS alone or F(ab)'(2) plus LPS had no or only marginal effects. Tumor establishment in brain was completely prevented in 36% of animals implanted with SKMEL-1 and 65% of animals implanted with NMB7. Twenty percent of established xenografts around the brain were eradicated but all animals had persistent tumor in the lumbosacral meninges despite treatment. Continuous intraventricular infusion of LPS produced a variable polymorphonuclear (PMN) pleocytosis that was dose-dependent. Continuous intraventricular infusion of 3F8 produced immunohistochemically detectable attachment to 86% of persistent brain deposits of tumor but <1% of spinal lumbosacral deposits. We conclude that regional therapy with anti-G(D2) MAb could target neutrophils to inhibit LM tumor growth. However, optimal activation and mobilization of neutrophils into the cerebrospinal fluid (CSF) and improved penetration of MAb to tumor sites remain critical variables.

Animals↗
PubMed1999

Intrathecal administration of an anti-ganglioside antibody results in specific accumulation within meningeal neoplastic xenografts in nude rats.

Intrathecal (i.t.) administration of monoclonal antibodies (MAbs) represents a new therapeutic approach for the treatment of leptomeningeal (LM) cancer, which is presently rapidly fatal. In this study, we quantitated the accumulation of an intrathecally administered anti-ganglioside GD2 MAb (3F8) within leptomeningeal neoplastic xenografts of GD2 positive melanoma and neuroblastoma in nude rats by measuring concentrations of radiolabeled and unmodified MAbs and by immunohistochemistry. Intrathecal administration of 125I-3F8 resulted in area under the tissue concentration versus time curve (AUC) values in SK-MEL-1 melanoma xenografts (53.1 microCi*h/g) that were 14-fold greater than in corresponding blood (3.9 microCi*h/g), whereas i.t. administration of a control nonspecific MAb resulted in AUC values in tumors (7.1 microCi*h/g) that were less than those in blood (9.5 microCi*h/g). Administration of acetazolamide and furosemide, which slow the clearance of IgG MAb from rat cerebrospinal fluid resulted in a fivefold increase in AUC of 125I-3F8 in melanoma (262.9 microCi*h/g). The highest concentration of 125I-MAb in tumor after i.t. administration was seen at the first sampling time of 2 h, and this fell to 50% of maximum values at 8-16 h. Pharmacokinetic analysis of unmodified MAb demonstrated retention of MAb within the LM space of animals with tumor. The concentration of MAb 3F8 appearing in serum after i.t. administration was 10-fold lower in animals with melanoma xenografts than in those without tumor implants. Radiation dose estimates after intraventricular administration of radiolabeled MAb indicated delivery to tumor of 1,870 rad/mCi of 125I-3F8 but only 40 rad/mCi of 125I-labeled control MAb. These results indicate that anti-ganglioside MAbs and other MAbs directed to tumor-associated antigens are excellent candidates for i.t. treatment of appropriate leptomeningeal cancers in humans.

Acetazolamide↗
PubMed1999

Identifying offspring of problem-drinking parents: comparison of five self-report measures.

Although there is general consensus that self-report measures are reliable in offspring identification of parental problem drinking, studies in which these measures are used differ in two important ways: 1) different self-report measures are used across investigations, and 2) when identical measures are used, idiosyncratic cutoff criteria are employed. The purpose of this study was to compare five self-report measures commonly used in college-age populations to identify problem-drinking parents. When the most conservative criterion was employed, each of the five measures identified similar percentages of offspring as having problem-drinking parents (10% for fathers and 4% for mothers). Interrelationships among the five measures were examined, and each method appeared to contribute both to the common and unique variance of the construct "parental problem drinking." Therefore no one measure can capture all aspects of a parent's drinking problem as reported by their offspring.

Adolescent↗
PubMed1998

Pharmacokinetics of IgG and IgM anti-ganglioside antibodies in rats and monkeys after intrathecal administration.

Intrathecal (i.t.) administration of monoclonal antibodies (mAbs) represents a new therapeutic approach for the treatment of leptomeningeal cancer, which is rapidly fatal. This study describes the pharmacokinetics of intrathecally administered mAbs in rats and monkeys to optimize their use for regional antineoplastic therapy. We hypothesized that mAbs, which are high-molecular-weight, polar compounds, would be eliminated from the cerebrospinal fluid (CSF) at the same rate as bulk flow of CSF. We found that an IgM mAb was cleared from rat CSF at the rate of CSF bulk flow (0.0041 ml/min), but an IgG mAb was cleared at a faster rate (0.011 ml/min). We attempted to reduce the CSF clearance of an IgG mAb by administration of acetazolamide and furosemide, which inhibit the rate of CSF production and CSF bulk flow. We demonstrated that the administration of acetazolamide and furosemide reduced the clearance of IgG mAb from rat CSF by 58%. These results establish that bulk flow of CSF determines a minimum rate of elimination from the CSF for IgM mAbs and that additional mechanisms operate to clear IgG mAbs from the CSF. Inhibition of CSF production by acetazolamide and furosemide increased the area under the CSF concentration vs. time curve of IgG mAbs in the CSF. The increased area under the CSF concentration vs. time curve is likely to improve the therapeutic index of these agents for i.t. therapy.

Animals↗
PubMed1997

Adeno-associated viral vector gene transfer into leptomeningeal xenografts.

Leptomeningeal carcinomatosis is a painful and debilitating complication of cancer. Indwelling reservoirs provide continuous assess to the subarachnoid space, making leptomeningeal cancer potentially amenable to gene therapy. Adeno-associated virus (AAV) is a defective virus not associated with any human disease. We used an AAV vector to transduce medulloblastoma (DAOY) cells in a nude rat model of leptomeningeal disease. After intraventricular injection of vector carrying the bacterial lacZ gene, beta-galactosidase positive cells were found in the implanted tumor and in ependymal and subependymal cells but not in underlying normal brain parenchyma. No evidence of virally-mediated toxicity was noted in the animals. The results of this pilot study demonstrate that AAV vectors may be used to transfer and express foreign genes in established leptomeningeal tumors.

Adenovirus E1A Proteins↗
PubMed1997

A rat model of leptomeningeal human neoplastic xenografts.

Leptomeningeal (LM) cancer spread from either a primary brain tumor or a systemic cancer is rapidly fatal. Current therapies are ineffective and highly toxic to normal nervous system tissues. A xenograft model of LM neoplasia in nude rats using a diversity of tumor cell types was established in order to evaluate new treatment strategies and to study the pharmacokinetics and biological effects of treatments administered into the subarachnoid space. Consistent leptomeningeal engraftment and progressive tumor growth was seen after intrathecal injection of 9 of 13 tumor cells lines, including 2 melanomas, 2 neuroblastomas, 2 medulloblastomas, 2 gliomas, and 1 breast cancer. Clinical signs ranged from steady weight loss commencing from the day after tumor implantation to absence of any signs for three weeks until the sudden occurrence of major neurological deficits or death. Pathologic examination showed only leptomeningeal tumor growth with some cell lines and severe parenchymal invasion with others. CSF cytology consistently demonstrated tumor cells in animals with LM disease. Cranial magnetic resonance (MR) following intravenous (i.v.) administration of a contrast agent revealed enhancing lesions one week following melanoma tumor implantation. Reliable ventricular puncture was demonstrated by radiography following intraventricular (IVent) injection of an iodinated contrast material. IVent instillation of saline, albumin, or antibodies did not provoke clinical toxicity or an inflammatory response.

Animals↗
PubMed1995

Non-sialate inhibitor of influenza A/WSN/33 neuraminidase.

An N1 strain of influenza A virus neuraminidase (A/WSN/33 NA) was purified and used to screen for inhibitors. As a result, a well-known tuberculostatic, 4'-formylacetanilide thiosemicarbazone (or thiacetazone), was identified. Thiacetazone is a non-sialate compound and inhibits the enzyme in a noncompetitive manner with respect to the substrate sialic acid. Mechanistic studies indicate that the inhibition was due to the competition of thiacetazone with Ca2+, which maintains N1 neuraminidase in an active conformation. The Ki for the inhibition was estimated to be about 4 microM. Equilibrium exchange experiments revealed that when purified A/WSN/33 NA was incubated with 5 microM 45CaCl2, 2 mol of 45Ca2+ ion was exchanged into each mole of NA tetramer and subsequently displaced from the enzyme upon the introduction of the inhibitor. Inhibition of plaque formation by thiacetazone in an MDCK cell culture that had been infected with the influenza A/WSN/33 virus was demonstrated. Thiacetazone was highly specific for A/WSN/33 neuraminidase, since little effect was noted when it was tested against NAs from the other strains of influenza virus or from bacteria. This compound might represent a group of non-sialate inhibitors of influenza NA that bind to a noncatalytic or an allosteric site on the enzyme.

Animals↗
PubMed1994

Transcription induces the formation of a stable RNA.DNA hybrid in the immunoglobulin alpha switch region.

We previously showed that the in vitro transcription of a negatively supercoiled plasmid containing the murine IgA switch region caused the formation of fewer supercoiled conformers of the plasmid due to the presence of a stable RNA.DNA hybrid. Here, we demonstrate that the RNA.DNA hybrid is approximately 140 nucleotides, and it forms regardless of the initial topological state of the transcription template. Transcription of the switch region in a relaxed closed circular plasmid generates positively supercoiled plasmid conformers that revert to their original relaxed state when treated with RNase H. Conformers that have incorporated a stable RNA transcript are also observed when nicked circular and linear plasmids containing the IgA switch sequences are transcribed with 32P-labeled nucleotide triphosphates. Once formed, the RNA.DNA hybrid is stable to both thermal and superhelical stress, tolerating temperatures in excess of 95 degrees C and restraining approximately 12 positive supercoils in the plasmid.

Animals↗
PubMed1994

Expression of reverse transcriptase from feline immunodeficiency virus in Escherichia coli.

Reverse transcriptase from feline immunodeficiency virus (FIV) has been cloned and expressed in Escherichia coli. We have purified this recombinant enzyme and shown that it is a 66-kDa protein that is indistinguishable from virion-derived FIV reverse transcriptase in sensitivity to the 5'-triphosphates of 3'-azido-3'-deoxythymidine and the four 2',3'-dideoxynucleosides. The availability of large quantities of the FIV reverse transcriptase will allow more detailed physical and pharmacological studies.

Amino Acid Sequence↗
PubMed1993

Characteristics of youths identified from a psychiatric case register as first-time users of services.

OBJECTIVE: The study examined associations between sociodemographic factors and first-time use of mental health services by children and adolescents, including whether the patterns differ by age at first treatment contact. METHODS: The authors examined sociodemographic characteristics of 4,949 youths listed on a psychiatric case register in Monroe County, New York, who were under age 19 when first seen for public mental health treatment between 1987 and 1989. Data on race and type of insurance for patients in the county's four catchment areas were compared with 1980 census data. Insurance was categorized as public (such as Medicaid) or private and was used as a proxy for socioeconomic status. RESULTS: Both minority and publicly insured youths of low socio-economic status were overrepresented in the treatment population in relation to their numbers in the county, although publicly insured youths from the poorest catchment area were underrepresented in the treatment population. Among children (ages five to 12) in the treatment population, males outnumbered females by 2 to 1, but among adolescents (ages 13 to 18), the numbers were similar. Among minority groups, children receiving first-time mental health services were more likely to have public insurance. Minority adolescents were somewhat more likely to be privately than publicly insured.

Adolescent↗
PubMed1991

Chimeric human immunodeficiency virus type 1/type 2 reverse transcriptases display reversed sensitivity to nonnucleoside analog inhibitors.

Human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT), an important therapeutic target in the treatment of AIDS, is effectively inhibited by a class of nonnucleoside analog compounds that includes nevirapine (BI-RG-587) and tetrahydroimidazo[4,5,1-jk]-[1,4]benzodiazepin-2(1H)-one and -thione. We show that both tyrosine residues at positions 181 and 188 flanking the putative catalytic site of HIV-1 RT are required for sensitivity of the enzyme to these compounds. HIV-2 RT, which does not have tyrosines at these positions, is resistant to these nonnucleoside analog inhibitors. Substitution of the HIV-2 RT amino acid residues at position 181 or 188 into HIV-1 RT results in an enzyme that is resistant to these compounds while retaining sensitivity to 3'-azido-2',3'-dideoxythymidine triphosphate. HIV-2 RT substituted with amino acids 176-190 from HIV-1 RT acquires sensitivity to these nonnucleoside analog inhibitors.

Affinity Labels↗
PubMed1990

Induction of RNA-stabilized DNA conformers by transcription of an immunoglobulin switch region.

A deletion DNA rearrangement is associated with immunoglobulin class switching from IgM to IgG, IgA or IgE This recombination occurs in immunoglobulin switch regions, which are complex, highly repetitive regions of DNA. As switch regions become transcriptionally active just before switch recombination, analysis of the behaviour of these sequences during transcription could elucidate the mechanism of switch recombination. Here, we report that transcription of a supercoiled plasmid containing the murine IgA switch region (S alpha) leads to a loss of superhelical turns. The resulting series of less supercoiled plasmids is stabilized by RNA-DNA hybrids formed by the nascent RNA transcripts, which remain base-paired with their DNA templates.

Base Composition↗
PubMed1990

Evaluation of image quality in individual films of double film packets.

A total of 47 double film packets were exposed of a radiographic standard (step-wedge), a clinical model (dried skull), and a clinical situation (endodontic therapy). Dentists were employed as expert observers to compare detail and definition between front and back films within each packet. Front films (those closest to the source) had significantly superior image quality compared to back films (those further from the source). In vitro radiographic trials were significantly similar to in vivo radiographic results.

Chi-Square Distribution↗
PubMed1990

Periapical biopsy report: an analysis of over a 10-year period.

Biopsy reports of specimens from the apices of 1659 teeth physically present at the time the biopsy was performed were reviewed. The following information was recorded from each report: (a) source of specimen, (b) sex of patient, (c) age of patient, (d) location of tooth associated with lesion, and (e) diagnoses reported. Data were recorded and analyzed by chi-square analysis to note significant differences. This study found that 52% of the lesions were granulomas, 42% cysts, 2% periapical scars, and 4% other disorders. No differences were found between males and females in regard to age and location of lesions. Overall, the most common location for lesions was the maxillary anterior, followed by maxillary posterior, mandibular posterior, and finally the mandibular anterior jaw. This also was the case for all age ranges except 60 to 69 yr of age where lesions in the maxillary posterior area were most common. More granulomas were detected in all areas except in the mandibular posterior area where cysts were more common.

Adult↗
PubMed1989

Pre-pre-B cells containing only cytoplasmic B220 can be induced by dendritic cells and T cells to differentiate in vitro.

We have derived from spleens of nude mice early B lineage cells that were phenotypically compatible with a pre-pre-B cell stage of differentiation. Although these cells containing large basophilic granules had the B lymphocyte antigen B220, in the cytoplasm, they had no surface B220, no cytoplasmic or surface immunoglobulin heavy or light chains, no surface Thy-1, and no surface Ia. In addition, they appeared to have little or no heavy chain gene rearrangements, including the D to J that occurs on both chromosomes prior to the VH rearrangement that forms the code for the C mu heavy chain polypeptide. Cells at even this early stage of differentiation could be induced by DC-T to express B220 on the surface and to synthesize and then to secrete immunoglobulins. These phenotypic changes were associated with a morphologic change in the cells to a lymphoblastoid appearance. Different patterns of immunoglobulin secretion resulted when pre-pre-B cells were cocultivated with DC-T from different tissues; SP DC-T induced the secretion of only IgM, PP DC-T induced the secretion of IgM as well as IgG and IgA. The early inductive event(s) appeared to occur during cell-cell contact in aggregates of the inducing DC-T and the pre-pre-B cells.

Animals↗