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Biomedical subjects

C L Johnson

Publications and source records attributed to C L Johnson.

At least 127 records · Page 7Linked to original sources
PubMed1989

Regional chemotherapy in an experimental model of Wilms' tumor in rats.

A s.c. experimental model of Wilms' tumor in rats was used to compare the effects of intratumoral treatment with vincristine plus actinomycin D to i.v. treatment with these chemotherapeutic drugs. The Wilms' tumor model is a fast-growing solid tumor that has been shown to be resistant to traditional clinical treatment procedures used for Wilms' tumor in man. Injection of the chemotherapeutic drugs directly into the tumor mass was found to be more effective than i.v. therapy in causing long-term remission of the tumor. Intratumoral therapy was also less toxic to the animals than i.v. therapy when measured by post-treatment survival rates and weight loss during the 1st week following treatment. However, intratumoral treatment caused an initial fibrosis of the tumor tissue, which resulted in a slower rate of absorption of the resultant fibrotic tumor mass than was seen in tumors treated i.v. Also, intratumoral injection resulted in necrosis of the overlying skin, which healed as the fibrotic tumor tissue was absorbed. Intratumoral treatment of a cervical tumor was found to cause the remission of a second major tumor mass located at some distance from the initial injection (i.e., in the lumbar region). No significant benefits were noted when dimethylsulfoxide (DMSO) was used in place of aqueous mannitol as a vehicle to deliver the chemotherapeutic agents. There was a significant correlation between the drug dose-to-tumor-size ratio (D/T ratio) and the effectiveness of the chemotherapy. When this ratio was high enough, a single treatment with a combination of vincristine and actinomycin D usually resulted in total remission of the experimental Wilms' tumor in response to either intratumoral or i.v. therapy.

Animals↗
PubMed1989

The Kmod blood group phenotype in a healthy individual.

This report describes a healthy blood donor whose red cells have weakened expression of Kell blood group antigens. Kell antigen activity could not be detected by flow cytometric analysis and was demonstrable only by sensitive serologic techniques. As with normal-strength Kell antigens, reactivity could be abolished by treatment with 2-aminoethylisothiouronium bromide (AET). The donor's red cells have Kx antigen activity. Other commonly tested blood group antigens (MNSs, Rh, P1, Lewis, Duffy, and Kidd systems) appear normal. Clinical and serologic examination showed that this case is different from previously described examples of modified Kell expression. The propositus's phenotype has remained unchanged for 19 months, which suggests that it is not a transient condition. However, family studies provide no evidence that it is inherited. A 93-kD protein, which reacted weakly by Western blot with rabbit antibody to Kell protein, was isolated from the propositus's red cells by immunoprecipitation. This finding was not reproduced in subsequent studies, which suggests that the quantity of Kell protein recovered was at the threshold level detectable by the technique used. The red cell phenotype is categorized as Kmod, of which this is the first example reported in a healthy individual.

Absorption↗
PubMed1989

Effect of change of diet on the mineral composition of rumen fluid, on magnesium metabolism and on water balance in sheep.

1. The effects of four diets on water intake, rumen fluid outflow-rate, rumen pH and mineral metabolism were studied in wether sheep. The diets were barley and hay, flaked maize and hay, dried grass and frozen grass. 2. Experimental periods were of 12 d duration, and plasma magnesium concentrations were lower at the end of treatment periods when the grass diets were given and were significantly different (P less than 0.05) at 11.00 and 20.45 hours. Also, the concentration was significantly lower with the dried-grass diet than with the frozen-grass diet (P less than 0.05). 3. The concentration of Mg in rumen fluid centrifuged at 30,000 g (ultracentrifuged) varied with the diet. Maximum concentrations (tmax) were reached 4 h later on the grass diets than on the hay and concentrate diets. In the latter case tmax coincided with that for calcium, potassium, chloride and ammonia. At this time sodium and phosphate were at a minimum. The concentration of Mg in ultracentrifuged rumen fluid was negatively correlated (r -0.89) with pH, which was significantly higher (P less than 0.01) at all times on the grass diets. This relation was also reflected in the apparent availability of Mg. 4. Total water intake on the frozen grass was about twice that on the barley and hay diet. The outflow rate of liquid from the rumen was higher on the frozen grass than on the other three diets. 5. The proportion of absorbed Mg excreted in urine was significantly influenced by diet.

Animal Feed↗
PubMed1989

Iron status: prevalence of impairment in three Hispanic groups in the United States.

Little is known about the iron status of Hispanic groups in the United States. Data from the Hispanic Health and Nutrition Examination Survey were used to estimate the prevalence of impaired Fe status for persons aged 5-74 y from three Hispanic groups: Mexican Americans (MAs), Cubans, and Puerto Ricans; prevalences were also calculated for non-Hispanic whites (NHWs) and non-Hispanic blacks (NHBs) using data from the second National Health and Nutrition Examination survey. A three-variable model called the MCV model was used to assess impaired Fe status. Prevalences based on the MCV model did not differ between Hispanic groups. Differences between Hispanics and non-Hispanics occurred only among 20-44-y-old females, where MAs had a higher prevalence than NHWs or NHBs. With this exception, these Hispanic groups do not appear to be at greater risk of impaired Fe status than non-Hispanics.

Adolescent↗
PubMed1989

Development of human embryonic and fetal dermal vasculature.

This report summarizes recent advances in the understanding of the structure and organization of the microvasculature in developing human skin. Previous observations suggested that the skin contains no blood vessels as late as eight weeks estimated gestational age (EGA). Computer reconstructions, in conjunction with light and transmission electron microscopy (TEM), however, demonstrated that specimens as young as 35-45 d show a level of vascular complexity previously unknown. The computer reconstructions showed that the vasculature was organized in one or two planes parallel to the epidermis. A simple, single plane was evident in specimens 40-50 d EGA, whereas specimens 50-75 d EGA showed two planes. Fewer vessels were continuous throughout the tissue sample in the younger specimens compared with the older specimens. Superior views highlighted the continuities and connections of vessels. The younger specimens showed more discontinuous segments of vessels when compared with the network established in the older specimens. In the earliest specimens examined morphologically (35-40 d), simple, capillarylike vessels were morphologically identifiable in presumptive dermis. The samples studied by TEM revealed detailed structure of the vessel wall including extreme attenuations and projections, plasmalemmal vesicles, and junctions similar to adult endothelial cells. Little or no basal lamina surrounded the vessel. The basal lamina first appeared in the form of amorphous deposits and eventually thickened and became continuous. By the end of the first trimester, the basal lamina still lacked the organization of adult cutaneous arterial and venous segments. These findings suggest that the major vascular organization of the dermis is defined in the first trimester of development.

Biomarkers↗
PubMed1988

Ethnic and racial differences in serum vitamin A levels of children aged 4-11 years.

Interpretation of differences in serum vitamin A levels observed between Hispanic and non-Hispanic children may be complicated by confounding environmental factors. Data from the Mexican-American portion of the Hispanic Health and Nutrition Examination Survey and the second National Health and Nutrition Examination Survey were used to explore these differences in 4-11-y-old Mexican Americans and non-Hispanic blacks and whites before and after accounting for vitamin-mineral supplement use and poverty status. Initial differences in mean serum vitamin A levels and prevalences less than 20 micrograms/dL (0.70 mumol/L) or less than 25 micrograms/dL (0.87 mumol/L) among the three ethnic or racial groups were reduced or eliminated after accounting for the two descriptive variables. These results support the hypothesis that differences in serum vitamin A levels between Mexican-American and non-Hispanic children in the United States are due more to environmental factors than to ethnicity.

Black People↗
PubMed1988

Serum retinol levels of persons aged 4-74 years from three Hispanic groups.

Previous research suggests that Hispanics in this country may have poor vitamin A status. Using serum retinol data from the Hispanic Health and Nutrition Examination Survey, we examined the vitamin A status of Mexican Americans (MA), Cubans, and Puerto Ricans (PR) aged 4-74 y. MA had lower mean serum retinol levels and higher prevalences of serum retinol in the range of 0.70-1.01 mumol/L than did Cubans in several age-sex groups. The prevalence (or percentage) of serum retinol in a range indicating possible risk of functional impairment was not elevated in any of the Hispanic groups except the females aged 18-44 y. However, a high percentage of children and adolescents in the three Hispanic groups had serum retinol values in ranges that might indicate less-than-optimal vitamin A status. Determination of vitamin A status requires a more definitive assessment than by serum vitamin A alone.

Adolescent↗
PubMed1988

Survey of burn education in entry-level physical therapy programs.

We investigated the extent of burn education in entry-level physical therapy curricula and also collected information about oncology instruction. A questionnaire was sent to the directors of 96 entry-level physical therapy curricula, and 76 directors responded. Most of the respondents (98.7%) indicated that burn and cancer management warranted lectures. The programs that quantified instruction averaged 4.8 hours of burn-related medical and surgical lectures and 4.2 hours of burn-related physical therapy procedure lectures. The instructional time devoted to oncology was slightly less. Physicians presented the medical and surgical lectures in 36% of the curricula and provided instruction with physical therapists and nurses in 39% of the curricula. Physical therapists alone presented the lectures on physical therapy procedures in 83% of the curricula. Sixty-three percent of the respondents believed that new graduates could effectively treat both patients with burns and those with cancer, but other respondents attached various qualifiers to their responses. Some respondents thought that new graduates could not adequately treat patients with burns (12%) or cancer (8%). Suggestions for future physical therapy burn education are given.

Burns↗
PubMed1988

Biochemical studies on McLeod phenotype red cells and isolation of Kx antigen.

Red cells of the McLeod blood group phenotype have weak Kell antigens, lack Kx antigen and have acanthocytic morphology. We have immunoprecipitated Kell antigens from McLeod red cells and show that they are markers on the same 93 kDa membrane protein that carries Kell antigens on normal red cells. However, as determined by Western immunoblotting, McLeod red cells have a marked deficiency of this protein. We have also studied the near-neighbour relationship of McLeod and common Kell red-cell membrane proteins by cross-linking intrinsic sulphydryl groups by oxidation, catalysed with orthophenanthroline and copper, or by cross-linking amino groups with dimethyl-3,3'-dithiobispropionimidate. Results were analysed by diagonal mapping in two-dimensional gels. No abnormalities of membrane protein inter-relationship were detected in McLeod red cells. We have isolated Kx antigen from K0 red cells by immunoprecipitation with human alloimmune anti-Kx serum, isolation of immune complexes from detergent-solubilized cell membranes with protein A-Sepharose and analysis of the eluted immune complex by SDS-PAGE under reducing conditions. Kx antigen is a marker on a red-cell membrane protein of approximately 37 kDa. Ko (Knull) red cells have about twice the amount of Kx antigen as do red cells of common Kell type. McLeod red cells have no detectable Kx antigen by serological tests or by immunoprecipitation.

Antigens, Bacterial↗
PubMed1988

Blood grouping with the Olympus PK7100 testing system.

The Olympus PK7100, an automated microtitre blood typing machine, identifies, aliquots, and dilutes samples, adds reagents, photometrically detects agglutination, and records reaction results, with a throughput of 240 samples/h. A total of 20,147 donors was tested in parallel with the Groupamatic 360. Of these, 207 could not be ABO typed after two runs. Three samples typed as B by the Olympus were found to be A2B. Seventy-seven could not be typed for D after two runs. Of these, 55 were Rh positive and 22 negative. The Olympus identified 37 of 48 Du positive samples as Rh positive, while it typed three as Rh negative, and eight as 'uncertain'. None of these samples was identified as Rh positive by the Groupmatic 360. The Olympus PK7100 is accurate, reliable, easy to operate, and capable of high throughput with minimal operator intervention.

ABO Blood-Group System↗
PubMed1988

Magnesium metabolism in the rumens of lactating dairy cows fed on spring grass.

Six rumen cannulated lactating Jersey cows were used to study the effects of an abrupt change from a dry diet to young spring grass on mineral metabolism in the rumen, on plasma Mg2+ levels and on water intake. There was an increase in the intake of dietary Mg2+ and concentration of ultrafilterable Mg2+ in rumen fluid when the grass was fed associated with a fall in plasma Mg2+ concentration and percentage urinary Mg2+ excretion. The pH of rumen fluid fell when the cows were fed grass and there was a close inverse relationship with the concentration of ultrafilterable Mg2+ and Ca2+. Changes occurred in the mineral composition of rumen fluid that interact to affect the absorption of Mg2+. The concentrations of NH3, ultrafilterable K+ and ultrafilterable Ca2+ increased and the concentration of ultrafilterable Na+ decreased. These changes were associated with an increase in the potential difference between rumen fluid and blood (positive). Water consumption fell abruptly when the grass was fed and some cows drank no water on several days. However, total water intake was almost doubled resulting in an increased rumen volume.

Animal Feed↗
PubMed1988

An evaluation of a dry-fat product as a source of supplemental energy in pig diets.

Three feeding trials (278 pigs) and one balance trial (14 pigs) were conducted to evaluate acceptance and utilization of diets containing a dry-fat product containing 90% fat. The fat was a mixture of equal parts vegetable and animal fats. In Trial 1, 4-wk-old pigs fed diets with 5% dry-fat added had average daily gain (ADG), average daily feed intake (ADFI) and gain/feed (G/F) values equal to pigs fed the diet containing 4.5% liquid fat, the unprocessed equivalent to the dry-fat. Values for G/F with both diets were higher (P less than .05) than for pigs fed the unsupplemented control diet. In Trial 2, dry-fat and roasted soybeans were compared as sources of supplemental fat in diets for finishing pigs. Both were efficiently utilized, with no differences (P greater than .05) among diets. In Trial 3, diets with 0, 5 and 10% levels of added dry-fat were fed to pigs from 34 to 100 kg. Rates of gain were not affected, but ADFI decreased (P less than .05) and G/F increased (P less than .05) with increased fat level. Carcass measurements were not affected by dietary treatment, but iodine number of backfat increased (P less than .05) with dietary fat level. In Trial 4, values for grams of N absorbed and retained and megacalories of energy absorbed and metabolized did not differ (P greater than .05) between diets with 0 and 5% added dry-fat. These results show that the dry-fat product was efficiently utilized by growing and finishing pigs.

Animals↗
PubMed1987

Epidemiology of bulimia and bulimic behaviors.

A number of studies in recent years have attempted to establish prevalence rates for bulimia as defined by the DSM-III criteria and for bulimic behaviors such as binge eating, purging, and restrictive dieting. The literature has reported widely differing estimates of these behaviors. A critique of these studies suggests that a variety of methodological issues probably accounts for the lack of consistency across reports. A review of the literature indicates that some behaviors which could be considered bulimic are extremely widespread. Some recent work highlights the importance of using both behavioral and attitudinal variables in an assessment of clinically significant bulimia associated with life impairment, which is much less prevalent.

Adolescent↗
PubMed1987

Microbiological assay of blood serum for the vitamin B12 status of dairy cows.

Four vitamin B12 assays were compared using blood sera from Friesian cows on winter diets or grazing. In herd 1, ten animals were blood-sampled three times at monthly intervals and the vitamin B12 concentration of the sera determined by the Poteriochromonas malhamensis and Lactobacillus delbrueckii assays. At all three sampling dates the results produced by the P. malhamensis assay were significantly greater than those produced by the L. delbrueckii assay. Cows in herd 2 were divided into two groups, each of 30 animals. One group was given a soluble glass bolus releasing cobalt and the other was unsupplemented. Milk yields were recorded throughout the experimental period and herbage samples were taken at intervals for cobalt determinations. Blood samples were taken at intervals from January to September 1983 and the vitamin B12 concentration of the sera determined by four different assay methods: the P. malhamensis and L. delbrueckii microbiological assays and the Becton Dickinson and RIA Products 'No-boil' radioassays. The last of these failed to detect vitamin B12 in any sample. There was a significant difference between the results obtained by the three other assays, with the Becton Dickinson radioassay consistently producing the lowest result and the P. malhamensis assay the highest result of the three. There was no significant effect of cobalt supplementation on milk yield.

Animals↗