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Biomedical subjects

M H Maxwell

Publications and source records attributed to M H Maxwell.

At least 73 records · Page 4Linked to original sources
PubMed1985

Granulocyte differentiation in the lymphoid organs of chick embryos after antigenic and mitogenic stimulation.

Sections of spleen, bursa of Fabricius or thymus glands from 17-day-old chick embryos stimulated with sheep red blood cells, phytohaemagglutinin (PHA-P), concanavalin A or lipopolysaccharide were stained by an "indirect" peroxidase technique that differentiates eosinophils from heterophils and cell counts were carried out. The tissues were also examined with the electron microscope. Whatever stimulus had been used, the light microscopical examination revealed that the predominant granulocytes belonged to the peroxidase-negative heterophil series, outnumbering the peroxidase-positive eosinophils. There were no significant changes in the number of cells between treatments and the saline-injected controls, except in the case of PHA-P stimulation, where a slight reduction in the number of heterophils and a concomitant increase in eosinophils was observed. This study has demonstrated that the heterophil is the main granulocyte present in the lymphoid organs during late embryonic life in the fowl. It challenges previously reported work that the predominant cells are eosinophils and monocytes.

Animals↗
PubMed1985

Blood pressure lowering and potassium conservation by triamterene-hydrochlorothiazide and amiloride-hydrochlorothiazide in hypertension.

Effects of once-daily doses of 50 mg triamterene with 25 mg hydrochlorothiazide and 5 mg amiloride with 50 mg hydrochlorothiazide were compared in a randomized, multicenter study of 84 adult subjects with mild to moderate hypertension (diastolic blood pressure 90 to 114 mm Hg). After a 3-wk placebo lead-in period, the subjects entered a 6-wk treatment period. The two drug regimens were compared with respect to antihypertensive effects and effects on serum potassium and magnesium levels during the final week of drug therapy, with the use of the last week of placebo therapy as a covariate. Both drug regimens substantially reduced mean supine systolic and diastolic blood pressures to well within normal limits; there was no significant difference the two groups. Twenty-four of the 41 subjects receiving triamterene-hydrochlorothiazide (59%) and 29 of the 43 patients receiving amiloride-hydrochlorothiazide (67%) had diastolic blood pressure less than 90 mm Hg at week 9. Five subjects receiving amiloride-hydrochlorothiazide (12%) and two subjects receiving triamterene-hydrochlorothiazide (5%) had hypokalemia (serum potassium level less than 3.5 mEq/l) at week 9. The average decrease in serum potassium levels during amiloride-hydrochlorothiazide therapy (-0.33 +/- 0.08 mEq/l) was greater than that after triamterene-hydrochlorothiazide (- 0.08 +/- 0.07 mEq/l). Serum magnesium levels were not changed by either regimen. Weight loss was greater in the amiloride-hydrochlorothiazide group than in the triamterene-hydrochlorothiazide group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Influence of egg storage on hatchability, embryonic development and vitamin status in hatching broiler chicks.

Storage of eggs for 14 d prior to incubation depressed hatchability by 10%. Most of the increase in embryonic mortality (64%) occurred during the first week of incubation, with a further 30% taking place during the third week. Chicks hatching from stored eggs did not show any increased incidence of physical abnormalities characteristic of vitamin deficiencies. Chicks from stored eggs showed haematological abnormalities characteristic of mild macrocytic anaemia. Such changes can result from deficiencies of folic acid or cobalamin. Biochemical and haematological data did not suggest impairments in the status of the chicks with respect to a range of other vitamins.

Animals↗
PubMed1985

Cardiovascular morbidity and mortality in HDFP patients 50-69 years old at entry.

Five-year morbidity and mortality in the Hypertension Detection and Follow-Up Program (HDFP) were stratified by age groups at entry to the study and by Stepped Care (SC) and Referred Care (RC) treatment groups. Although the incidence of stroke increased with age in both treatment groups, the greatest reduction in strokes for SC versus RC occurred in the older age groups: 44.3% for ages 60-69, 33.0% for ages 50-59, and 24.6% for ages 30-49. Conversely, the 30-49-year SC group showed a greater reduction of myocardial infarction than their RC counterparts, with only marginal benefit in the older SC patients. There was a lower rate of left ventricular hypertrophy (LVH) or cardiomegaly and a higher rate of reversal in those who had LVH or cardiomegaly at baseline in all SC age groups versus RC. HDFP patients 50 years and older at entry in the SC group had a substantial reduction in cardiovascular morbidity and mortality as compared with age-matched RC patients. It is likely that these benefits were the result of successful lowering of blood pressure.

Adult↗
PubMed1985

Obesity and hypertension: long-term effects of weight reduction on blood pressure.

Long-term follow-up studies were conducted on massively obese hypertensive subjects during and after a successful protein supplemented fast (PSMF) in order to correlate blood pressure changes with caloric intake and body weight. The blood pressures in 43 subjects were compared during rapid weight loss and at identical weights during post-fast weight gain (Study A). Blood pressures and body weights in 50 subjects were compared prior to starting PSMF and prior to restarting the program 21 months later (Study B). One hundred twenty-five compliant subjects were observed after one month of weight maintenance (Study C-1), and 39 subjects were followed during six months of weight maintenance (Study C-2). In Study A, during subsequent weight gain on an unrestricted diet blood pressure was significantly higher than at identical weight during continuous weight loss on PSMF. However, this increase in blood pressure was only approximately 30 percent of the original decrease. In Study B, weight loss and blood pressure reduction were significantly correlated. After one month of weight maintenance following continuous weight loss of 73 lb, there was no increase in blood pressure (Study C-1). A small but significant increase in blood pressure after six months (Study C-2) was associated with similar small weight increment. However, all blood pressures remained well within the normotensive range and significantly lower than control values. In this study, long-term changes in blood pressure correlated with changes in body weight.

Blood Pressure↗
PubMed1985

Heterophilic leucocytes are the predominant granulocytes in the ovary and ultimobranchial glands of the adult fowl.

Pieces of ovary and ultimobranchial gland from adult laying hens were examined by an indirect peroxidase technique which differentiated tissue eosinophil and heterophil leucocytes. The results showed that in both organs, brown-staining peroxidase-positive eosinophils were greatly out-numbered by pink- to red-staining heterophils, thus demonstrating that eosinophils are not the dominant granulocyte present, as has been widely reported. It is suggested that the heterophils may be required in a phagocytic role.

Animals↗
PubMed1985

Nuclear lobe index in avian eosinophilia.

The nuclear lobe index was calculated for eosinophils from adult fowl, ducks and quail with spontaneous or experimentally induced eosinophilia. Appropriate control birds were also examined. The nuclear lobe index in normal fowl was 1.95 compared with 1.91 in birds with eosinophilia. Although these results (in the fowl) are almost identical, further analysis revealed a distinct 'shift to the right' in those birds with counts greater than 20 per cent eosinophils (P less than 0.01). The normal nuclear lobe index in ducks was 2.68 compared with 2.60 in those with eosinophilia and thus no 'shift' was recognised. The quail, on the other hand, demonstrated a slight 'shift to the left' in which the normal nuclear lobe index was 2.46 compared with 2.20 lobes per cell in eosinophilic quail.

Animals↗
PubMed1985

Electron microscopy of the juxtaglomerular apparatus in young fowl fed a salt deficient diet.

Kidneys from young fowl fed a salt deficient diet for up to five weeks were examined under the electron microscope. The presence of maculae densae (MD) were confirmed and the concentrations of nuclei in the MD and the remainder of the distal convoluted tubules were compared. In the proximal convoluted tubules, salt deprivation caused mitochondrial changes, an increase in intranuclear and cytoplasmic lipid and the deposition of urates. Regional thickening of the glomerular basement membrane was observed in many kidneys. In the normal kidney, there is an age dependent increase in the juxtaglomerular granules in the cortical glomeruli (P less than 0.02), but not in the juxtamedullary glomeruli. In salt deprived birds, juxtaglomerular granules were increased in the juxtamedullary glomeruli (P less than 0.01) but not in the cortical glomeruli. Salt deprivation also caused a significant reduction in bodyweight after five weeks (P less than 0.002) and increases in heterophil (P less than 0.02) and monocyte (P less than 0.05) counts in the blood.

Animals↗
PubMed1984

The distribution and localisation of acid trimetaphosphatase in developing heterophils and eosinophils in the bone marrow of the fowl and the duck.

The distribution and localisation of acid trimetaphosphatase was investigated in developing heterophils and eosinophils from fowl and duck. In the heterophils of both species, trimetaphosphatase activity progressively increased in concentration from a thin peripheral band in the round immature primary granules to a fairly dense uniform reaction product in most of the mature specific spindle-shaped granules. Fowl and duck primary eosinophil granules had a similar distribution of reaction product as heterophils. In duck specific eosinophil granules the crystalline interna or externa, or both regions, contained strong activity whereas in the fowl, the activity of the specific granules was strongly-uniform in appearance.

Acid Anhydride Hydrolases↗
PubMed1984

Histochemical identification of tissue eosinophils in the inflammatory response of the fowl (Gallus domesticus).

A staining technique was developed for the differential identification of tissue eosinophil and heterophil leucocytes in the fowl. Pieces of formalin-fixed skin, challenged with dinitrochlorobenzene (DNCB) or citraconic anhydride (CA), were incubated in a substrate suitable for peroxidase prior to embedding in either paraffin wax, glycol methacrylate or Araldite. This results in deep brown staining of the eosinophil granules while those of the heterophils remain unstained. Heterophils and eosinophils were conspicuous at 30 minutes after challenge in the early inflammatory response. By 48 hours the heterophilic response had diminished and eosinophils had almost disappeared. Only mononuclear cells were seen at 72 hours. It is suggested that the eosinophil leucocyte might act as an early modulator of inflammation in delayed-type hypersensitivity responses in the fowl.

Animals↗
PubMed1984

BP changes in obese hypertensive subjects during rapid weight loss. Comparison of restricted v unchanged salt intake.

A controlled prospective study compared two groups of obese hypertensive subjects during 12 weeks of a hypocaloric protein-supplemented fast containing 40 mEq of sodium daily. One group received additional sodium chloride sufficient to maintain baseline sodium intake measured prior to the fast (210 m/Eq/day). Sodium restriction resulted in greater weight loss and slightly greater BP reduction only during the initial week of fasting. Thereafter, despite sodium equilibrium, further substantial weight loss and BP reduction were identical in both groups, the decrement in weight being linear (1.89 kg/wk) and the BP reduction asymptotic. Although the initial reduction in BP during the first week of supplemented fast may be attributable to negative salt and water balance, the further reduction in BP during a period of constant sodium balance must be caused by weight loss per se or by the triggering of other antihypertensive mechanisms associated with weight reduction.

Blood Pressure↗
PubMed1984

Renal osteodystrophy.

Patients with chronic renal failure often suffer from severe metabolic bone disease. This is usually either osteitis fibrosa cystica or osteomalacia. While parathyroidectomy is indicated in osteitis fibrosa cystica, desferrioxamine is an exciting new development in the treatment of osteomalacia.

Aluminum↗
PubMed1984

Ultrastructural study of the liver and kidney in ochratoxicosis A in young broiler chicks.

Ultrastructural changes are reported in the kidney and liver of 20-day-old broiler chicks fed ochratoxin A (OA), incorporated in the diet at levels of 2 and 4 ppm. Changes in the kidney included the presence of abnormally shaped mitochondria in the proximal convoluted tubules. There was an increase in the size and number of mitochondrial dense granules and cytoplasmic peroxisomes. Intranuclear and cytoplasmic lipid droplets and electron dense round bodies in the dilated smooth endoplasmic reticulum were also noted. Regional thickening and degeneration of the glomerular basement membrane was observed in some cases. In the liver from OA fed birds there was an increased accumulation of cytoplasmic glycogen in the hepatocytes. Abnormal mitochondrial ring forms in the kidney and the accumulation of glycogen in the liver are considered to be of diagnostic significance in ochratoxicosis of young broiler chicks. The severity of the changes was found to be dose related. These results suggest that the mitochondria in the proximal convoluted tubules of kidney were most sensitive to OA toxicity.

Animals↗
PubMed1982

Error in blood-pressure measurement due to incorrect cuff size in obese patients.

Trained nurse-specialists obtained 84 000 blood-pressure measurements in 1240 obese subjects using cuffs of the three standard adult sizes in a randomised order. The differences in readings between the three cuffs were smallest in non-obese subjects and became progressively greater with increasing arm circumference (AC) in the obese population. The regular cuff (12 X 23 cm) showed the greatest bias in relation to AC. Formulae and a table have been derived to correct the measurement error caused by cuffs of inappropriate size at various ACs. The reported high prevalence of hypertension in obese subjects may be greatly overestimated.

Arm↗