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Biomedical subjects

L Baker

Publications and source records attributed to L Baker.

At least 145 records · Page 8Linked to original sources
PubMed1988

Failure of a human immunodeficiency virus (HIV) immune globulin to protect chimpanzees against experimental challenge with HIV.

To assess the possible efficacy of passive immunization against human immunodeficiency virus (HIV) an immune globulin was prepared from plasma of HIV-seropositive donors selected to be among those having the top 12.5% of virus-neutralizing antibody titers. The immune globulin was treated with pepsin to render it intravenously tolerable. The preparation, which we termed HIVIG, neutralized 100 tissue culture 50% infective doses (TCID50) of HIV at an average dilution of 1:1000 in neutralization tests in vitro. During preparation HIVIG was subjected to virus inactivation and removal procedures that in theory resulted in a reduction in HIV infectivity by a factor of 10(25). At a dose of 9-10 ml/kg of body weight both the virus-inactivated source plasma and the final immunoglobulin preparation were noninfective and without adverse effect in two chimpanzees. Two chimpanzees inoculated intravenously with HIVIG at 1 ml/kg and two inoculated with 10 ml/kg were challenged intravenously 1 day later with 400 TCID50 of the same strain of HIV (HTLV-IIIb) used in neutralization assays in vitro. All animals became infected. Incubation periods to virus isolation (by cocultivation with human mononuclear cells) in HIVIG recipients did not differ significantly from the incubation period seen in a control animal that received a normal anti-HIV-free immunoglobulin. These findings may have implications for understanding the failure of experimental vaccines to protect against HIV challenge in chimpanzee experiments.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Inflatable surface coil for MR imaging of the prostate.

An inflatable surface coil for transrectal magnetic resonance imaging of the prostate was designed. The coil was tested during imaging of an insulated saline phantom and of the prostates of four patients. Phantom images were comparable to those obtained with commercial coils of similar size. High spatial resolution and excellent contrast were noted in coronal images of the prostates. Use of this coil could substantially improve studies of the prostate and cervix.

Humans↗
PubMed1988

A wire-sheath system for MR-guided biopsy and drainage: laboratory studies and experience in 10 patients.

On the basis of laboratory experiments, we devised a wire-sheath system for MR-guided biopsy and drainage and then evaluated that system in 10 patients. The localizing system consisted of a 20-gauge plastic sheath into which a stainless-steel alloy wire had been inserted. In laboratory studies, we compared this wire-sheath assembly with other materials to determine its optimal visualization on MR images. We then used the same wire-sheath system to perform 16 procedures (in 10 patients), including six biopsies, five diagnostic fluid aspirations, and five catheter drainages of infected and noninfected fluid collections. The laboratory results showed that the wire-sheath assembly cast a 7-mm artifact, was visualized well on all pulse sequences, and was safe within the magnet (minimal attraction). The assembly was visualized well in each patient and provided adequate localization. MR-guided biopsy and drainage can be performed with high-resolution detail by using this wire-sheath system. Potential uses of this system include (1) treatment of lesions that can be seen on MR images only (or that can be seen to significantly better advantage on MR images than on sonograms or CT scans), and (2) treatment of patients in whom avoidance of the radiation delivered by CT is imperative.

Adolescent↗
PubMed1988

Application study of N-hexadecane on pig skin.

Pig skin was treated with N-hexadecane. Epidermal mitoses, epidermal and dermal histopathology, epidermal phospholipase A2 activity were investigated. The most prominent increase of mitoses was found 48 hours after three applications of n-hexadecane. Epidermal and dermal changes were observed mainly at the same time. Phospholipase A2 activity was decreased when increased mitoses and histological changes were seen. This paradoxical movements of the activity of this enzyme has also been reported in regard to psoriasis.

Alkanes↗
PubMed1988

Insulin-gene sharing in sib pairs with insulin-dependent diabetes mellitus: no evidence for linkage.

An association between insulin-dependent diabetes mellitus (IDDM) and an RFLP adjacent to the insulin gene has been consistently observed, but its etiological significance is unclear. We studied unrelated IDDM patients (N = 45) and controls (N = 65) to confirm the association--and assessed evidence for linkage in 22 families with at least two affected (IDDM) sibs--to determine whether the insulin-gene region actually contributes to susceptibility to IDDM. All individuals were typed for the RFLP in the 5'-flanking region of the insulin gene (5'FP) used in the previous studies, and the 12 families not fully informative for linkage with the 5'FP were typed for additional closely linked RFLPs. We found a higher frequency of class 1 alleles of the 5'FP in IDDM patients (.83) than in controls (.75), which is consistent with the reported association, but the difference was not statistically significant in our sample. Among the 33 affected sib pairs (ASPs) in 22 families, if maximum possible sharing is assumed when sharing is ambiguous, 10 pairs share both parental insulin genes, 17 pairs share one, and six share neither. This distribution is incompatible with close linkage. In contrast, for the HLA region, for which all 22 families are fully informative, 19 of the 33 ASPs share two haplotypes and the remaining 14 share one. There are no pairs that share neither HLA haplotype. Thus, although these data clearly illustrate the contribution of HLA-linked susceptibility to IDDM, they argue strongly against a contribution of similar magnitude by the insulin-gene region.

Diabetes Mellitus, Type 1↗
PubMed1988

Colon cancer: medical therapy.

Fluorouracil is the major chemotherapy agent currently available for colon cancer. It is utilized alone or in combination in a variety of schedules, though the optimal schedule has not yet been identified. In addition to the use for metastatic disease, fluorouracil also is useful for adjuvant treatment or in combination with radiation therapy for treatment of locoregional disease.

Colonic Neoplasms↗
PubMed1987

Experimental doxorubicin myopathy. A permanent treatment for eyelid spasms?

Doxorubicin may effect a more permanent chemomyectomy and chemodenervation (by retrograde "suicide transport") of the orbicularis oculi muscle than the chemodenervation produced by botulinum A toxin used for the treatment of blepharospasm. Graded doses (0.4 mg and 1.0 mg) of doxorubicin hydrochloride (2 mg/mL) were injected into the eyelids and antecubital and popliteal skin of rabbits in an attempt to evaluate the drug's efficacy and safety. Histologic changes in the orbicularis oculi muscle included necrosis and decreased mass. The results are promising because the eyelids appear to be more resistant than other skin regions to the development of tissue necrosis. Moreover, doxorubicin might not be excessively toxic in the treatment of eyelid cancer.

Animals↗
PubMed1987

Detection of human immunodeficiency virus (HIV) genome from the lymphocytes of homosexual men.

Human immunodeficiency virus (HIV) is the primary etiological agent of acquired immunodeficiency syndrome (AIDS). This virus can be transmitted by blood or blood products. Homosexual males (HM) are regarded as one of the high-risk groups for AIDS. Lymphocytes obtained from HM were used for cocultivation with fresh HIV antibody negative lymphocytes. The presence of virus particles was monitored by reverse transcriptase (RT) activity. Three out of eleven donors were found to have reverse transcriptase activity. All three donors were also found to be HIV antibody positive. HIV DNA from infected cells was detected by dot blot hybridization. The number of genome per cell is low. The correlation between RT activity and the cytolytic effect of HIV will be discussed.

Cytopathogenic Effect, Viral↗
PubMed1987

Esophageal chest pain. Value of high-dose provocative testing with edrophonium chloride in patients with normal esophageal manometries.

The unequivocal diagnosis of esophageal chest pain requires the demonstration of simultaneous manometric changes and chest pain. Numerous provocative agents have been used to enhance the diagnostic value of esophageal manometry. Our aims were to: evaluate consecutively a large group of patients with proven noncardiac chest pain and normal baseline manometric studies, using edrophonium chloride, 10 mg, and determine the value of provocative testing in clinical practice. One hundred twenty patients with normal standard baseline esophageal manometries were studied using blinded testing with edrophonium chloride and followed clinically by questionnaire. A positive response of both chest pain and manometric changes was observed in 34%, a negative response in 49%, and an indeterminate response in 17% of patients. Baseline manometric features, including high-amplitude contractions, did not predict the response to edrophonium chloride. Following edrophonium chloride administration, the change in amplitude, duration, and number of repetitive contractions from baseline was significantly greater in positive responders. Edrophonium decreased the velocity of propagated contractions in positive responders (P less than 0.05), but not in nonresponders. Response to edrophonium chloride could not be predicted by patient age, sex, or clinical symptomatology. Seventy percent of patients in both groups had symptoms indistinguishable from ischemic heart disease. After making a specific diagnosis of esophageal chest pain, patients showed a marked clinical improvement, with a significant decrease in physical limitation, emergency room visits, hospital and CCU admissions, and in further cardiac testing. We conclude that provocative testing with edrophonium chloride will make it possible to definitively implicate the esophagus in over 30% of patients with normal baseline manometric findings and noncardiac chest pain.

Adult↗
PubMed1987

Factors associated with the development of psychiatric illness in children with early speech/language problems.

This paper reports on the correlates of psychiatric illness in children with speech and language disorders. Of 600 children selected from a community speech clinic, 50% were found to have diagnosable psychiatric disorders according to DSM-III criteria. These "psychiatrically ill" children were compared to the "psychiatrically well" children in the sample on a variety of developmental, socioeconomic, medical, and psychosocial factors. Although some differences were found between the well and ill children in other factors, the majority of the differences, and the most highly significant differences, were found in areas of linguistic functioning. It is hypothesized that this finding may be relevant not only to understanding the association between linguistic and psychiatric functioning but also to predicting the outcome and planning treatment for childhood speech and language disorders.

Adolescent↗
PubMed1987

Prevalence and type of psychiatric disorder and developmental disorders in three speech and language groups.

Six hundred children with communication disorders presenting to a community clinic were evaluated for psychiatric and developmental disorders. The 600 children fell into three subgroups: those with "pure speech disorders," those with "speech and language disorders," and those with "pure language disorders." The two subgroups with language involvement had higher rates of both psychiatric and developmental disorders than the children with pure speech involvement. Those children with language involvement also had a different pattern of psychiatric diagnoses than the children with pure speech disorders. Possible etiological factors and clinical significance of these findings are discussed.

Child↗
PubMed1987

Prevalence, clinical significance, and strain specificity of neutralizing antibody to the human immunodeficiency virus.

A semiautomated microtiter assay has been developed to quantitate neutralizing antibody to the human immunodeficiency virus. This assay has been found to be highly specific. Forty-four sera that were negative by enzyme-linked immunosorbent assay (ELISA) were tested under code: 42 were negative (less than 1:2), and 2 had titers of 1:2. By contrast, of 178 sera positive by western blot, 92.7% had detectable neutralizing antibody, and 12.5% had titers greater than or equal to 1:128. Neutralizing antibody titers correlated poorly with clinical diagnosis and T4/T8 ratios. Different isolates differed quantitatively in their sensitivity to neutralization by antibodies obtained from different patients; however, all strains tested so far have been neutralizable by all the sera tested. Neutralizing antibody titers correlated weakly, if at all, with direct or competition ELISA titers.

Antibodies, Viral↗