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Biomedical subjects

C Finch

Publications and source records attributed to C Finch.

At least 55 records · Page 3Linked to original sources
PubMed1992

Thyroid function in a formerly goitrous community on Karkar Island, Papua New Guinea.

During a survey of noncommunicable disease conducted on Karkar Island, Madang Province in 1986, measures of thyroid function were examined in adult residents of a formerly goitrous village (Gamog) and a neighbouring community (Marup) with no history of iodine deficiency or endemic goitre. In Gamog, almost 20% of males and almost 30% of females had palpable goitre (maximum prevalence at ages 35-54 years) but visible goitres were not encountered. However, thyroid function tests were generally similar in the two groups, suggesting that iodine deficiency is no longer an appreciable problem for adults in Gamog. The persistence of palpable goitre in this village is therefore likely to be a residual effect of previous iodine deficiency. Correction of the iodine deficiency in the Gamog community began with the program of iodized oil injections, which was undertaken in the 1970s. The current lack of iodine deficiency is probably due in the main to dietary change associated with the introduction of the cash economy. This effect may have occurred in many formerly goitrous communities in Papua New Guinea in recent years, although persistence of iodine deficiency in some parts of the country should not be discounted.

Adult↗
PubMed1991

Glucose tolerance in Papua New Guinea: comparison of Austronesian and non-Austronesian communities of Karkar Island.

Epidemiological studies in Pacific populations have suggested a relationship between glucose tolerance and proportional Austronesian genetic admixture, with non-Austronesian Melanesians relatively free of glucose intolerance. However, a survey conducted in 1985 demonstrated the apparent emergence of glucose intolerance in a peri-urban non-Austronesian community, casting doubt on this hypothesis. In 1986 glucose tolerance was studied in three village communities on Karkar Island, Papua New Guinea. Two were of Austronesian and one was of non-Austronesian genetic ancestry. Prevalence of diabetes was low in all communities. However, prevalence of impaired glucose tolerance (IGT) was 7% in the more developed Austronesian community, as compared with 2% in the equivalent non-Austronesian group (p less than 0.05). Multiple regression analysis demonstrated not only a highly significant association between 2-h plasma glucose and insulin concentrations (p less than 0.001), but also that for a given value of plasma insulin, 2-h plasma glucose values were lower for non-Austronesian than for Austronesian subjects (males, p less than 0.05, females, p less than 0.01). However, average plasma insulin concentrations were relatively high in the non-Austronesian community, despite lower average plasma glucose concentrations.

Adult↗
PubMed1990

Plasma glucose and insulin responses in young Papua New Guineans (aged 10-19 years).

A study of rural and periurban children aged 10-19 years in the Tolai population of Papua New Guinea has demonstrated a higher average plasma glucose concentration and relative hyperinsulinaemia after an oral glucose challenge in the periurban group. The findings could not be explained by differences in age or adiposity. In the rural children, plasma insulin concentration remained consistently low throughout the range of glucose tolerance, indicating a high degree of insulin sensitivity. In the periurban children there was a marked increase in plasma insulin concentration with increasing plasma glucose concentration, possibly suggesting the development of insulin resistance, or an antecedent state, and incipient glucose intolerance. In view of the potential public health implications of these findings, further ecological studies of insulin response in children and adolescents would appear warranted. These should include appropriate measures of pubertal development, which is a possible confounding factor not addressed in the present study, as well as addressing the role of nutritional factors.

Adolescent↗
PubMed1989

Glucose tolerance in Papua New Guinea: ethnic differences, association with environmental and behavioural factors and the possible emergence of glucose intolerance in a highland community.

That Melanesians of non-Austronesian genetic ancestry may be relatively resistant to glucose intolerance was supported by the results of a study of two semitraditional non-Austronesian villages in the Papua New Guinean highlands in 1983, in which an absence of diabetes and a high degree of glucose tolerance and insulin sensitivity were observed. The second of this series of surveys was conducted in 1985 in three non-traditional communities: a periurban, non-Austronesian village in the highlands, and rural and periurban Austronesian villages in coastal locations. Although an absence of diabetes was demonstrated once again in the highlanders, these periurban subjects showed an unexpectedly high insulin response which may be a precursor of glucose intolerance. The notion that highland communities that are living in non-traditional circumstances in Papua New Guinea presently are in "metabolic transition" towards diabetes and other non-communicable diseases, if correct, is of importance to the public health of the nation. In the periurban, coastal-dwelling Austronesians, diabetes with severe hyperglycaemia was demonstrated, and there was some evidence of a secular trend towards increasing glucose intolerance. The two-hour plasma glucose concentrations were shown to be associated with obesity, modernity and Seventh-Day Adventist religious persuasion. However, important and unexplained differences in glucose tolerance remained between rural and periurban coastal dwellers after taking these factors into account.

Adult↗
PubMed1986

Iron metabolism in the Belgrade rat.

Iron metabolism in the Belgrade rat was examined in the intact animal and in the reticulocyte suspensions. The plasma iron turnover was increased. However, when allowance was made for the effect of the elevated plasma iron concentration, erythroid marrow capacity for iron uptake was at basal levels. Numbers of erythroid cells in marrow and spleen measured by the radioiron dilution technique were increased. Thus iron uptake was not proportionate to the erythroid hyperplasia in the b/b rat, despite a more than adequate plasma iron supply. This relative deficiency in iron uptake was reflected in a severe microcytosis and elevated red cell protoporphyrin. Reticulocyte incubation studies demonstrated an unimpaired uptake of the transferrin-iron-receptor complex but a marked reduction in iron accumulation. The diferric transferrin molecule, when it did give up iron within the cell, released both of its iron atoms so that only apotransferrin was returned to the media. In contrast to the nearly complete release of iron within the normal reticulocyte, the major portion of iron taken up by the Belgrade reticulocyte was returned to the plasma. The release mechanism that can be impaired in iron-deficient reticulocytes by EDTA or cadmium was shown to be affected by lower concentrations of these substances in the Belgrade reticulocyte. It is concluded that the Belgrade rat has an abnormality of iron release within the absorptive vacuole that is responsible for a state of intracellular iron deficiency, involving the erythron and other body tissues.

Anemia, Hypochromic↗
PubMed1984

Effect of exposure to low temperature on normal and iron-deficient subjects.

Twenty-one Venezuelan peasants were segregated into three groups on the basis of measurements of iron status: seven normal subjects, six iron-deficient subjects with normal hemoglobin and eight iron-deficient subjects with a hemoglobin concentration of less than 9 g/dl. All subjects were placed in a water bath at an initial temperature of 36 degrees C. The water temperature was then rapidly lowered to 28 degrees C, and observations were made over the period of 1 h. Mean oral temperature of the first group fell 0.2, the second group 0.5, and the third group 0.9 degrees C. Mean plasma norepinephrine levels in both groups of iron-deficient subjects were significantly higher at 36 degrees C and during cold exposure compared with control subjects. Oxygen consumption was also significantly increased in both groups of iron-deficient subjects after cold exposure.

Adult↗
PubMed1984

Effect of iron-deficiency anemia on hormone levels and thermoregulation during cold exposure.

When exposed to an ambient temperature of 4 degrees C, iron-deficient anemic rats become hypothermic. This lesion is related more to anemia than to tissue iron deficiency, since exchange transfusion to hematocrits over 25 restored normal thermoregulatory performance. Likewise poor cold responses were induced in control rats by transfusion to low hematocrits. Cold sensitivity in all anemic animals was paralleled by poor thyroid responses: there was a significant positive correlation between hematocrit and percent rise in triiodothyronine (r = 0.63) and thyroxine (r = 0.53) during 6 h at 4 degrees C. Basal levels of thyroid-stimulating hormone (TSH) were similar in control and iron-deficient animals: after cold exposure, TSH rose to higher levels in those animals with hematocrits over 25 than in those with lower hematocrits. Diminished O2 delivery to tissues responsible for heat production is probably a major component of the cold sensitivity of anemic rats. The novel finding that thyroid hormone responses are compromised by anemia implies effects on hormonal regulation that may also contribute to this functional lesion.

Anemia, Hypochromic↗
PubMed1984

Iron supply for erythropoiesis in the rabbit.

Marrow radioiron uptake and marrow blood flow were measured in order to evaluate iron supply for erythropoiesis. Normal, phenylhydrazine-treated and bled animals were studied. The plasma iron turnover of seven normal rabbits was 1.49 +/- 0.22 mg/dl whole blood per d, of 11 rabbits treated 4 d before with phenylhydrazine was 5.16 +/- 1.81, and of four bled animals the plasma iron turnover was 3.75 +/- 1.61. The cardiac output and the percentage of blood flow to the marrow was increased in phenylhydrazine-treated and bled animals. Marrow iron flow in phenylhydrazine-treated animals was 38.3 +/- 32.6 micrograms/min per kg as compared with control values of 7.0 +/- 1.3 (P less than 0.01). This was due to an increase in marrow flow, an increase in plasma iron, and an increase in plasmatocrit. In bled animals, in spite of an increased marrow blood flow, marrow iron flow of 7.3 +/- 2.2 was similar to that of control animals due to a lower plasma iron concentration. The calculated marrow iron extraction of 3.7 +/- 2.4% in phenylhydrazine-treated animals was not different from that of control animals of 4.3 +/- 1.1, whereas extraction was increased in bled animals to 7.9 +/- 1.3 (P less than 0.01). In additional studies of transfused animals, acutely induced anemia was associated with an increased cardiac output, but also with a relative decrease in marrow flow, which left marrow iron supply unaffected. It would appear from these studies that an important mechanism for meeting the increased iron requirement of the hyperplastic erythroid marrow is an increase in marrow blood flow.

Animals↗
PubMed1983

Psychomotor performance in the senescent rodent: reduction of deficits via striatal dopamine receptor up-regulation.

In order to determine the relationship between striatal dopamine (DA) receptor density and psychomotor performance in senescent animals, two experiments were carried out. In the first, the age-related motor deficits were characterized using a battery of four psychomotor tests (rod walking, wire hanging, inclined screen, plank walking). These tests were administered to three groups of male Fischer rats (mature, 6-8 months; middle aged, 12-18 months; and senescent, 25 months) and performance measured. Age-related differences were observed on all the tasks, with the oldest animals showing the poorest performance. These animals were then used in a second experiment in which one-half of the group of animals from each age was administered 1.86 mg/kg/day of haloperidol for 14 days (via surgically implanted Alza Minipumps. Control groups of animals from each age were given pumps which contained only the vehicle (HCl diluted with distilled water, pH = 2.9). Following the 14 day drug administration, the pumps were surgically removed and 3 days later all the groups were retested on the psychomotor tests. Stereotypy (to 0.5 mg/kg of apomorphine, sniffing, licking, grooming and cage crossings) was also re-examined. Results show that haloperidol-treated animals from all three age groups display greater response times (i.e., better performance) than vehicle-treated animals on the battery of four motor tests and, the haloperidol-treated old animals exhibit more sniffing and grooming than the vehicle-treated old animals. Parallel increases in [3H]spiperone binding seen in all haloperidol-treated groups suggest a relationship between increases in the density of striatal DA receptors and improvement in motor performance.

Aging↗
PubMed1982

Basis of plasma iron exchange in the rabbit.

Rabbit transferrin in vitro is shown to load ferrous iron at random on its specific binding sites. The release of iron to reticulocytes is shown to be an all-or-none phenomenon. The two monoferric transferrins have similar in vivo plasma iron clearance rates and tissue distribution. Diferric transferrin, while giving a similar tissue distribution of radioiron, has a plasma iron clearance rate approximately twice that of the monoferric transferrins at low plasma iron concentrations. This difference diminishes as the plasma iron concentration increases. These results are consistent with a progressively greater in vivo conversion of mono- to diferric transferrin as transferrin saturation increases. The in vivo plasma iron turnover in the rabbit increases progressively as the plasma iron increases, from a mean value of approximately 0.8 mg/dl whole blood per d at a plasma iron concentration of 50 mug/dl to 2.0 at a plasma iron concentration of 300. The molecular behavior of transferrin and its iron over this range was investigated using (125)I-transferrin, [(55)Fe]monoferric transferrin, and [(59)Fe]diferric transferrin. The equilibrium distribution of transferrin between its apo-, mono-, and diferric moieties was similar to that predicted on the basis of the percent saturation and random distribution. Rate constants of iron loading and unloading calculated from the percent saturation and from the clearance rates of [(55)Fe]monoferric and [(59)Fe]diferric transferrin were similar to those derived from changes in injected (125)I-apotransferrin. On the basis of these data, it is concluded that the plasma transferrin pool is nonhomogeneous and that the relative size of the mono- and diferric cycles depends on transferrin saturation. A formula is proposed for correcting the plasma iron turnover, thereby eliminating the effect of plasma iron concentration, so as to reflect directly the number of tissue transferrin receptors.

Animals↗
PubMed1981

Interaction of human diferric transferrin with reticulocytes.

Methods have been devised for preparing human transferrin with a different isotope of iron selectively labeling each of the two iron binding sites and for determining the distribution of radioiron among transferrin molecules. When diferric human transferrin was exposed to human or animal reticulocytes, there was an equal contribution of radioiron from the acid-stable and acid-labile sites. In this delivery, both atoms of iron were removed simultaneously from the diferric transferrin molecule, converting it to apotransferrin. At similar iron concentrations the amount of iron delivered by diferric transferrin was twice that delivered by monoferric transferrin.

Animals↗
PubMed1981

Uptake and release of iron from human transferrin.

Purified fractions of human apotransferrin, monoferric transferrins with iron on the acid-labile binding site and on the acid-stable binding site, and diferric transferrin have been prepared. The iron loading and unloading behavior of these preparations has been examined by isoelectric focusing. Iron release from the two monoferric transferrin preparations to human reticulocytes was of similar magnitude. In a mixture containing equal amounts of diferic and monoferric iron, approximately 4 times the amount of iron delivered by the monoferric species was delivered by the diferric species. Iron loading of transferrin in vitro showed a random distribution between monoferric and diferric transferrin. Among the monoferric transferrins, loading of the acid-labile binding sites was greater than that of the acid-stable binding sites. In vivo iron distribution in normal subjects, as evaluated by in vitro-added 50Fe, gave similar results. Absorption of a large dose of orally administered iron in iron-deficient subjects resulted in a somewhat greater amount of diferric transferrin at low saturation and a somewhat smaller amount of diferric transferrin at higher saturations than would have been anticipated by random loading. These data would indicate that in the human, iron loading of transferrin may be considered essentially random. Unloading from the two monoferric transferrin species is of similar magnitude but far less than that delivered by diferric transferrin.

Binding Sites↗
PubMed1981

Hazard of lead exposure in the home from recycled automobile storage batteries.

Two families from rural areas of North Carolina had excessive lead exposure which resulted from either recycling exhausted automobile storage batteries in the home or burning the discarded battery casings for home heating. One child developed encephalopathy resulting in permanent brain damage. Decontamination efforts reduced the quantity of lead in the home environment by greater than 50%. Rural children, previously considered to be at low risk, may in fact receive profound exposures which may go unrecognized until encephalopathy occurs. Occupational histories should be obtained from parents in order to detect children at risk from environmental toxins brought into the home on workmen's bodies and clothing.

Automobiles↗