Search PubMed⌕ Search

Biomedical subjects

W A Carter

Publications and source records attributed to W A Carter.

At least 37 records · Page 2Linked to original sources
PubMed1987

Clinical, immunological, and virological effects of ampligen, a mismatched double-stranded RNA, in patients with AIDS or AIDS-related complex.

10 patients with the acquired immunodeficiency syndrome (AIDS), AIDS-related complex (ARC), or lymphadenopathy syndrome (LAS) were given 200-250 mg ampligen, a mismatched double-stranded (ds) RNA with in-vitro antiviral activity against human immunodeficiency virus (HIV), twice a week for up to 18 weeks, without side-effects or toxicity. In all 9 patients who were positive for HIV RNA in peripheral blood mononuclear cells before therapy, levels became undetectable between days 10 and 40 of the start of therapy. 6 of the 7 patients with ARC or LAS also showed a progressive reduction in HIV load as measured by co-culture assays. All 10 patients had augmentation of delayed-type hypersensitivity skin reactions. Other changes noted during ampligen therapy included an increase in or maintenance of numbers of helper-inducer T lymphocytes, improvements in HIV-related symptoms, rises in titre of neutralising antibodies against HIV, and restoration of proper functioning of the natural lymphocyte antiviral dsRNA-dependent (2'-5'-oligoadenylate/RNA-ase L) pathway. Thus, in the short term, ampligen seems to have the dual ability to restore immunological function and to control HIV replication.

AIDS-Related Complex↗
PubMed1987

Mismatched double-stranded RNA (ampligen) reduces concentration of zidovudine (azidothymidine) required for in-vitro inhibition of human immunodeficiency virus.

'Ampligen', a non-toxic, mismatched polymer of double-stranded RNA with antiviral and immunomodulatory activities reduced the concentration of zidovudine (azidothymidine, AZT; 'Retrovir', Wellcome) required for inhibitory activity against human immunodeficiency virus (HIV) in vitro. At the higher doses of AZT tested, the virustatic activity observed seemed to have a synergistic virustatic relation with ampligen. Thus, combined therapy with ampligen and AZT can be expected to be more beneficial than AZT alone to patients with the acquired immunodeficiency syndrome (AIDS) or AIDS-related complex since AZT regimens that seem to be clinically effective are associated with considerable toxicity.

Antiviral Agents↗
PubMed1987

Human non-malignant and malignant brain tumor derived cell cultures: proliferation and sensitivity to natural human fibroblast (beta) interferon.

Twenty-one human brain tumor biopsies were processed by mechanical and enzymatic methods to produce mixed cell suspensions. Cultures were prepared in small plastic flasks, and primary outgrowth occurred in 16/21 cultures. The period required for primary outgrowth ranged from 3 days to 14 days. We established serial propagation with 15/16 of the primary cultures. Sensitivity to HuIFN-beta was determined between passages 3 to 12, using a microassay based on cell viability (uptake of a supravital stain, neutral red). Extracted dye was quantified in acidic-methanol using the MR580 Microelisa Autoreader (Dynatech). We observed a broad range of responsiveness to the drug among the 12 cell-strains tested. Thus, 4 cell strains were relatively sensitive; 4 were resistant to 10(4) IRU/ml of purified HuIFN-beta. Four cell strains exhibited a level of responsiveness that was intermediate to that of these two groups. During propagation of these biopsies, cytopathology suggestive of paramyxovirus-infection appeared in 4 of the cell-strains. This characteristic was not uniformly associated with high sensitivity to human beta interferon which is a very potent, naturally occurring antiviral substance. Our results support the concept that information concerning sensitivity to HuIFN-beta and other cytostatic agents may be rapidly obtained using microcultures of brain tumor cultures in conjunction with supravital stain uptake studies. Additionally, these results suggest that further clinical studies with beta interferon should be undertaken to define the parameters which determine successful in vivo application.

Astrocytoma↗
PubMed1987

Growth of astrocytomas in the human tumor clonogenic assay and sensitivity to mismatched dsRNA and interferons.

Nine astrocytoma specimens were received from seven patients and processed for testing in the human tumor clonogenic assay (HTCA). Cells derived from these specimens were challenged with human natural alpha-interferon (alpha-IFN) and beta interferon (beta-IFN), recombinant beta interferon (beta ser-IFN), and mismatched double-stranded (ds) RNA (Ampligen). Six of the astrocytoma specimens formed adequate colonies for drug sensitivity testing (greater than or equal to 30 colonies/plate), and all were high-grade (III-IV) tumors. Sensitivity was defined as a greater than or equal to 50% decrease in tumor colony formation following drug exposure and was observed with alpha-IFN (2/4), beta-IFN (3/4), and mismatched dsRNA (4/5) exposure. No decrease in colony growth was observed after recombinant beta ser-IFN exposure, and in 2 of 3 cases, colony formation was stimulated. The sensitivity of 75 non-CNS solid tumors to mismatched dsRNA was compared to the high-grade astrocytomas in the HTCA. Of the 10 additional histologic tumor types studied, carcinoid and renal cell carcinomas exhibited the greatest sensitivity to mismatched dsRNA: 63% and 52%, respectively. However, in comparison, 80% of the high-grade astrocytomas were sensitive, demonstrating that these gliomas are among the most sensitive of human tumors to mismatched dsRNA in vitro. Clinical trials of interferons and mismatched dsRNA, coupled with in vitro sensitivity studies, should further define their therapeutic potential.

Astrocytoma↗
PubMed1987

Augmented antitumor effect of combined human natural interferon-alpha and mismatched double-stranded RNA treatment against a human malignant melanoma xenograft.

The antitumor effect of combined natural human interferon-alpha (IFN) and mismatched double-stranded RNA (dsRNA) treatment against the human malignant melanoma cell line, BRO, was studied. In vitro results, using a tissue culture antiproliferative assay, indicated that these cells were moderately sensitive to IFN-alpha. In contrast, mismatched dsRNA had no antitumor effect, and a minimal stimulation of cell growth, over part of the concentration range tested, was observed. Mismatched dsRNA did not potentiate the antitumor effect of IFN-alpha in cells receiving combination treatment. Xenografts of BRO cells, inoculated subcutaneously into nude mice, were used to evaluate the antitumor effects of IFN-alpha and mismatched dsRNA. Growth of the primary tumor was inhibited by both drugs alone or in combination (p less than 0.001), but the combined treatment was most effective and appeared to be additive. The number of spontaneous lung metastases was also inhibited (p less than 0.02) in all treatment groups. Survival, however, was significantly increased only in the IFN-alpha/mismatched dsRNA group (p less than 0.02 compared to controls, p less than 0.05 compared to mismatched dsRNA alone). Determination of splenic natural killer (NK) cell activity against BRO cells demonstrated that significantly augmented NK activity to the same extent, but that the IFN-alpha alone had no effect. These results indicate that IFN-alpha worked through direct antiproliferative mechanisms while mismatched dsRNA stimulated host immunomodulatory effects. The increased tumor growth inhibition and survival in the dual treatment group appears to result from the combined direct antiproliferative and indirect immunomodulatory effects.

Animals↗
PubMed1986

Familial occurrence of breast cancer is associated with reduced natural killer cytotoxicity.

A factor in the incidence of spontaneous neoplasms in mice is the endogenous level of natural cell-mediated cytotoxicity. These immunosurveillant or host defense mechanisms are probably under the control of multiple gene products including interferons. We studied natural killer (NK) cytotoxicity using peripheral blood mononuclear cells from 59 normal individuals with either a high (17) or low (42) familial incidence of breast cancer. The K562 cell line was used as target in 51Cr release assays. Three effector: target ratios (6.2:1, 25:1, and 50:1) were studied in quadruplicate using 3, 4 and 5-h incubations. Significantly lower natural killer activity (p less than 0.002) was detected in normal individuals with high familial incidences of breast cancer compared to individuals with low incidences in each of the three separate assays (50:1). The same conclusion was reached whether the data were expressed in terms of lytic units per 10(7) blood mononuclear cells or as % specific 51Cr released. Thus, a relationship was observed between the occurrence of breast cancer in closely related family members and low natural cell-mediated cytotoxicity. This result suggests that defects in NK activity may play a role in the initiation of human breast tumors. However, prospective studies will be necessary to establish whether low NK cell activity is a risk factor for breast cancer.

Adult↗
PubMed1986

Antiproliferative effect of mismatched double-stranded RNA on fresh human tumor cells analyzed in a clonogenic assay.

Colony growth in soft agar was used to identify human tumors that were sensitive to the direct antiproliferative effects of mismatched dsRNA (Ampligen). The results suggest that different human solid malignancies vary significantly in their sensitivity to Ampligen. Tumors with 50% or more of their surgical specimens showing sensitivity included carcinoid, glioblastoma, and carcinomas of the kidney, and lung. Resistant tumors (less than 15% sensitivity) included sarcomas and colo-rectal carcinomas. Overall, 42% of the tumor specimens studied showed a 50% or greater reduction in tumor cell colony formation after a single initial treatment with Ampligen (250 micrograms/ml). Interestingly, one patient's tumor which was de novo sensitive to interferon (IFN), but emerged as IFN-resistant following IFN therapy, remained sensitive to Ampligen. Thus, a clonogenic assay may prove useful in identifying human tumors and individuals for clinical trials with Ampligen, including patients resistant to IFN.

Base Composition↗
PubMed1986

Serum protein masking of the thermal sensitivity of the antiviral activity of purified human beta interferon: implications for clinical studies.

Human beta-interferon (HuIFN-beta) exhibits antiproliferative and antiviral properties. Successful clinical application of this drug depends on knowledge of the thermal stability of these activities under physiological conditions. In the present study, both the antiproliferative and antiviral activities were stabilized by the addition of very small quantities of serum proteins. This supplement was sufficient to mask the slightly higher thermosensitivity of the antiviral activity. In the absence of serum proteins, the values of both the half-life and the energy of activation were higher for the antiproliferative activity than for the antiviral function. Each had a half-life of at least 24 h and identical values for the energy of activation in the presence of proteins furnished by 1% fetal bovine serum. This study provides additional evidence to support a thesis recently advanced by Carter et al. that the antiproliferative domain of glycosylated beta interferon may be separable from the antiviral domain. It is concluded that the efficacy of HuIFN-beta, under clinical conditions, will not be seriously impaired by thermal inactivation. Antiviral assays of serum may be freely substituted for antiproliferative assays during pharmacological studies.

Blood Proteins↗
PubMed1985

Independent evolution of antiviral and growth-modulating activities of interferon.

Interferon (IFN) may be an extraordinarily ancient antiviral defense used by animals and plants. In animals, the antiviral properties of IFN may have been rendered redundant in part by the evolution of cell-mediated immunity. Comparative analysis of gene and protein structures, combined with examinations of biological specificities, suggest that IFN-beta and IFN-gamma have evolved new functions that include regulation of hematopoietic cell differentiation. An inspection of the events required for growth control by IFN suggests that this evolution consisted of the addition of an "antiproliferative domain" to a primitive IFN molecule that was previously capable of eliciting only an antiviral response. These evolutionary considerations lead to the speculation that some molecular species of IFN-alpha retain specific and potent biological activities, whereas other species may be losing both target cell specificity and biological potency over time. Important clinical problems, as well as opportunities, are raised by these hypotheses, particularly the problem of toxicity to normal organs resulting from the chronic use of certain cloned interferons at the relatively high doses that may be necessary to compensate for evolutionary alterations in their structure and function.

Amino Acid Sequence↗
PubMed1985

Comparative studies of ampligen (mismatched double-stranded RNA) and interferons.

Historically, it has been assumed that double-stranded (ds) RNAs function at a cellular level exclusively via an interferon (IFN) induction mechanism. However, current studies conducted both in the laboratory and at the clinical level reveal that this assumption is incorrect and, indeed, underestimates the intrinsic antitumor activity of certain dsRNAs. A specific dsRNA (Ampligen) shows strong antiproliferative activity against human carcinoid tumor cells in a clonogenic assay when natural alpha- and beta-IFNs were inactive. Similarly, in vivo studies in which human renal cancer cells were transplanted into athymic mice demonstrate a strong antitumor effect of Ampligen whereas such tumors are largely unaffected by alpha-IFN treatment. In a comparative study including many fresh human tumors of various histological types (breast, ovarian, melanoma, renal, and carcinoid) numerous examples were uncovered of Ampligen sensitivity (antiproliferative effect) in the face of relative or complete insensitivity to IFNs. Synergistic effects of Ampligen plus IFN overcame the resistance of some human tumor cells to either biological modifier given alone. It can also be demonstrated that the antitumor action of Ampligen on certain human lung tumor cells is not shared by polyinosinic . polycytidylic acid, thus indicating that different dsRNAs may themselves exhibit dissimilar effects on various human tumors.

Animals↗
PubMed1985

Antiproliferative and immunomodulatory actions of beta-interferon and double-stranded RNA, individually and in combination, on human bladder tumor xenografts in nude mice.

A cell line, RT4, derived from a human transitional cell carcinoma of the bladder, was grown as a xenograft in athymic mice. The growth of the xenografts was inhibited by beta-interferon (IFN-beta), polyriboinosinic acid.polyribocytidilic acid, the mismatched double-stranded RNA analogue r(I)n . r(C12,U)n, and to a lesser extent recombinant IFN-beta, when treatment was initiated at the time of tumor inoculation. In contrast, the growth rate of established tumors, approximately 6 mm in diameter at the initiation of therapy, was inhibited by both double-stranded RNAs, but not natural IFN-beta, indicating a possible tumor size dependence on the effectiveness of IFN-beta. Combinations of natural or recombinant IFN-beta with either polyriboinosinic acid.polyribocytidilic acid or r(I)n.r(C12,U)n gave an antagonistic effect regardless of tumor mass at the initiation of treatment. This antagonism could be overcome by alternating r(I)n. r(C12,U)n and natural IFN-beta treatment. Natural killer cell activity against RT4 cells in culture was augmented in the spleens of mice treated with r(I)n.r(C12,U)n, but not in those treated with natural IFN-beta. RT4 cells treated in culture with IFN-beta, however, were significantly less efficient as targets for natural killer cells from r(I)n.r(C12,U)n-treated and control spleens. These results indicate that: the effectiveness of IFN-beta may be related to the tumor mass; double-stranded RNAs appear to work, at least partially, in an indirect, immunomodulatory manner; combination therapy can yield an antagonistic rather than an additive or synergistic antitumor effect; and strategic scheduling can overcome the antagonistic effect of combination therapy.

Animals↗
PubMed1985

Preclinical studies with Ampligen (mismatched double-stranded RNA).

Historically, double-stranded (ds) RNAs have been largely over-looked as potentially valuable anticancer/antiviral drugs, primarily because of the many clinical toxicities and lack of efficacy associated with the first clinically tested dsRNA--polyinosinic-polycytidylic acid (rIn X rCn). However, studies summarized herein demonstrate that the therapeutic ratio of dsRNAs can be greatly enhanced by purposeful mispairing of bases. For example, a mispaired dsRNA, termed Ampligen (rIn X r(C12,U)n), shows strong antitumor activity in a variety of relevant test systems with little or none of the toxicities associated with rIn X rCn. Furthermore, Ampligen demonstrates a much wider therapeutic spectrum than that displayed to date by any single type of interferon (natural or recombinant DNA-derived). Importantly, Ampligen, the product of a straight-forward enzymatic synthesis, shows excellent lot-to-lot biological and biophysical specifications, which is often not the case with biologically derived new compounds. Furthermore, a significant fraction of human solid tumors, which are largely unresponsive to conventional chemotherapy or interferon (IFN), is sensitive to Ampligen in a fresh human tumor clonogenic assay. Indeed, whereas 50% of untreated and IFN-treated athymic mice engrafted with human renal cancer cells die within 20-22 weeks, mice treated with Ampligen survive a minimum of 32 weeks (p less than 0.0003). A summary of all animal models tested and human clinical trials to date demonstrates that Ampligen exerts a greater antitumor activity than IFN and has a superior therapeutic ratio compared to rIn X rCn.

Animals↗
PubMed1985

Clinical studies with ampligen (mismatched double-stranded RNA).

Results of an ongoing clinical study of a mismatched double-stranded (ds) RNA, termed Ampligen, in patients with metastatic cancer are described. In a pilot study of Ampligen (lot 1) involving mostly hematologic malignancies, patients received cumulative doses up to approximately 450 mg without untoward effects. Evidence of biologic/antitumor effects was observed (3/5 patients) by monitoring tumor-specific markers or tumor cell morphology. In patients with solid tumors receiving lot 2, Ampligen cumulative doses over 4 g were well tolerated. The drug was given by intravenous infusion (10-80 mg/infusion, twice weekly), in some instances for more than 1 year, without clinically significant side effects. Specifically, no evidence of hematologic, liver, or renal toxicity, which was previously noted with other dsRNAs, was observed. Side effects consisted of occasional mild fatigue or flu-like symptoms. Fever, when encountered, was transient and low grade (less than 100.5 degrees F). Importantly, an analysis of patient sera for dsRNA antibodies revealed that no patient had evidence of specific antibodies directed against Ampligen. Other dsRNAs cause up to a 60% incidence of antibody formation. Additionally, a novel method was developed to monitor Ampligen blood levels. In a survey of seven patients, Ampligen had a mean plasma half-life of 23 min. Ampligen administration can also result in activation of both natural killer (NK) cells and a lymphocyte, interferon-associated, intracellular enzyme. Dose-dependent antitumor effects were seen in several solid tumors; in doses of 10-40 mg, 3/9 patients showed stable disease for up to 1 year. At the 80-mg dose level, 2/5 patients showed tumor regressions (mixed and partial responses).(ABSTRACT TRUNCATED AT 250 WORDS)

Antibody Formation↗
PubMed1984

Antiproliferative effect of natural beta interferon on fresh tumor cells analyzed in a clonogenic assay.

Natural beta interferon (beta IFN), derived from diploid fibroblasts, has been evaluated for its antiproliferative activity using a panel of twelve different histologic types of fresh human tumor cells. Thirty-nine percent (9/23) of the tumors showed a 70% or greater decrease in colony formation following exposure to 500 international reference units per ml of natural beta IFN, a concentration which is in the clinically achievable range. Interesting, is that leiomyosarcoma, a tumor relatively resistant to conventional chemotherapy, was uniformly sensitive (3/3) to natural beta IFN. Indeed, the antiproliferative activity of beta IFN was consistently superior (in 19/20 comparative assays) to the other conventional chemotherapeutic drugs evaluated for leiomyosarcomas. This study, which suggests that natural beta IFN exhibits significant antiproliferative activity on a variety of fresh human tumor cells, may be useful in orienting clinical trials with natural beta IFN (still in limited supply because of its unique physicochemical nature) to the more susceptible human malignancies.

Cell Division↗
PubMed1984

Low natural cytotoxicity of peripheral blood mononuclear cells in individuals with high familial incidences of cancer.

The possible role that natural cell-mediated cytotoxicity may play as a host defense mechanism against malignant tumors was investigated. We measured natural cell-mediated cytotoxicity (51Chromium released) in 79 normal individuals using K562 leukemia cells as targets in quadruplicate assays after 3, 4, and 5 hr of incubation using three different effector:target cell ratios (6.2:1, 25:1, and 50:1). Natural cell-mediated cytotoxicity was significantly lower (p less than 0.005) in each of the nine separate assay conditions for individuals with a high familial incidence of cancer compared to individuals with a low incidence of cancer. Moreover, natural cell-mediated cytotoxicity inversely correlated with the number of family members with cancer. The relationship between high familial cancer incidence and low natural cell-mediated cytotoxicity was observed in males as well as in females and in nonsmokers as well as in smokers. The same conclusion was reached whether the data were expressed as percentage of 51Chromium released, as lytic units per 10(7) mononuclear cells, or as lytic units per ml of peripheral blood. Thus, defects in natural cell-mediated cytotoxicity may play a role in the initial stages of human tumorigenesis. It may also be possible to identify individuals at increased risk of cancer development.

Adult↗
PubMed1983

Human brain tumor--derived cell lines: growth rate reduced by human fibroblast interferon.

The biological response modifier human beta-interferon had pronounced antigrowth effects on various histologic types of human brain tumor cells but no effects on a nontransformed cell line, MRC-5. The cultures of brain tumor cells showed severe alterations indicative of cell injury and death after exposure to beta-interferon for 2 to 6 days. Similar results were obtained with cells freshly explanted from human brain tumors. The results indicate that it may be possible to use fresh, explanted tumor tissue to identify patients who might benefit from therapy with beta-interferon.

Brain Neoplasms↗