New disposable ERG electrode made of anomalous polyvinyl alcohol gel

We developed a disposable electrode for the electroretinogram made of anomalous polyvinyl alcohol gel. This new hydrogel is a rubber-like elastic with water content 80-90 wt%, but insoluble in water. The elastic electrode plate is approximately 0.3-1.0 mm thick, sterile, flexible, and easily cut to the desired shape. Its low cost permits it to be discarded after use.

The normal c-wave amplitude in rabbits

We examined some of the problems arising when c-waves are employed in pharmacological experiments with pigmented rabbits. The cyclic variations of the c-wave are smaller in rabbit than in other species. Under our experimental conditions the c-wave amplitudes in some rabbits reached an equilibrium under intermittent stimuli, while in others they increased with time and did not reach a constant level within 3 h. The c-wave amplitude varied with the standing potential during dark adaptation. However interindividual variations made it difficult to standardize the c-waves by this change. Since the c-wave amplitudes of the right and left eyes were similar, the contralateral eye should be used as a control when drugs are administered topically. Interindividual variations of the c-wave amplitude were smaller under dim light. This method is useful in chronic pharmacological experiments when drugs are administered systemically.

Effect of glucose added to intraocular irrigating solutions on the rabbit electroretinogram in vitro

The most adequate concentration of glucose in intraocular irrigating solution for the retina was studied electrophysiologically in the pigmented rabbit in vitro. Comparison of b-wave amplitudes demonstrated that glucose at a concentration of 20 mM/l yielded the highest values. A 40 mM/l glucose solution also increased the b-waves but to a lesser extent than did a solution of 20 mM/l. This result might be due to the detrimental effects of osmolarity. However, under hypoxic conditions the amplitudes of the b-wave obtained with 40 mM/l glucose solution was greater than those with 20 mM/l. It thus appears that slight hyperglycemic concentrations might have favorable effects on the ischemic retina.

High 24-hour urinary C-peptide excretion in non-insulin dependent diabetes mellitus

The 24-hour urinary C-peptide excretion (UCPR) is a useful means of estimating total daily insulin secretion. To evaluate the daily insulin secretion rate in non-insulin dependent diabetes mellitus (NIDDM), we measured UCPR in 22 patients with NIDDM and 18 normal subjects. The mean (±SD) UCPR in the patients with NIDDM was 115.4±40.2 ug/day and that in normal subjects was 56.7±22.0 ug/day respectively with significantly higher values in the patients with NIDDM (P<0.0001). UCPR was positively correlated with body fat mass determined by measurement of skin fold thickness in both groups [r=0.51 in patients with NIDDM (n=22; p<0.02) and r=0.55 in normal subjects (n=18; p<0.02)], and was higher in NIDDM patients, even with the same degree of fat mass. There was no significant correlation between UCPR and body muscle mass both in the patients with NIDDM and normal subjects [r=0.16 in patients with NIDDM (n=22; p>0.1) and r=0.16 in normal subjects (n=18; p>0.1)]. This result suggested that the total daily insulin secretion rate in NIDDM be increased to compensate insulin resistance, especially that induced by adipose tissues.

Paradoxical enhancement of the ERG c-wave by a small dose of sodium iodate

The early effects of sodium iodate (NaIO3) on the ERG c- and b-waves were studied in rabbits. When 30 mg NaIO3/kg body weight was administered intravenously, the c-wave amplitude decreased and was replaced by a potential of opposite polarity. However, the administration of 20 mg/kg of NaIO3 enhanced the c-wave remarkably. Twenty min after administration, the mean c-wave amplitude significantly increased (P less than 0.001) to 211 +/- 6.2% of the pre-administration amplitude, whereas that of the control was 108 +/- 13.0%. The b-wave amplitude showed no significant changes. When 10 mg/kg of NaIO3 was administered, the enhancement of the c-wave was not remarkable. These effects were similar in both pigmented and albino rabbits. A lower blood concentration of NaIO3 applied to the basal side of the retinal pigment epithelium (RPE) may initially affect only the basal membrane of the RPE resulting in the decrease in the basal membrane resistance (Rba). This would explain the transient increase in the c-wave amplitude with 20 mg NaIO3/kg.

Portal blood flow measured by duplex scanning during mesenteric infarction

The portal blood flow of a 70-yr-old man with suspected massive mesenteric infarction was measured using duplex scanning. The main portal flow was 109 ml/min, while cardiac output was 4.2 L/min. Laparotomy revealed a massive mesenteric infarction from proximal jejunum to rectum. Duplex scanning may be a useful method for studying the course of mesenteric infarction.

Androgen receptors in ventral prostate glands of zinc deficient rats

Androgen binding has been studied in the prostate cytosol of zinc deficient rats by charcoal assays. Rats were housed individually in plastic cages and maintained on a zinc deficient diet for 3 months. The cytosol fraction of prostate gland was incubated with various concentrations of tritiated methyltrienolone (3H-R1881, a synthetic androgen) alone or in the presence of 500-fold excess of radioinert R1881. Scatchard analysis of the data revealed that the number of androgen binding sites in the cytosol fraction of the zinc deficient rat prostate was 31 +/- 5.2 fmol/mg cytosol protein. This was significantly lower than that (84 +/- 11.5 fmol/mg protein) of the controls. Their dissociation constant (Kd = 1.6 +/- 0.6 nM) on the other hand was not different from that (1.7 +/- 0.7 nM) of control animals. This decrease in the concentration of cytosol receptor sites in the zinc deficient state suggests that this metal is involved in the androgen-binding process in the target cells.

The effect of glucocorticoid on 125I-insulin binding to human erythrocytes. Possible postreceptor modulation of receptor binding

To evaluate the role of insulin receptors in the pathogenesis of insulin resistance observed in glucocorticoid excess, we measured 125I-insulin binding to circulating erythrocytes in 7 patients with Cushing's syndrome and 7 patients with adrenal insufficiency. Insulin receptor binding was higher in Cushing's syndrome and was lower in adrenal insufficiency, compared to normal subjects. Insulin binding decreased after transsphenoidal surgery in 2 patients with Cushing's syndrome. In addition, glucocorticoid treatment in 6 patients with adrenal insufficiency resulted in the increase of insulin binding. The biological significance of this phenomenon must await further investigation, but it does suggest that insulin resistance in glucocorticoid excess should be interpreted as an alteration of cellular mechanisms of insulin at a step distal to the insulin receptor. Increased insulin binding to the receptor is probably modulated by postreceptor events.

Some problems involved in employing the ERG c-wave in pharmacological experiments: conditioning in pigmented rabbits

The large inter- and intra-individual variations in ERG c-waves have prevented the application of the component in pharmacological experiments on the retinal pigment epithelial function. We examined some of the problems involved in employing the c-wave in pharmacological experiments using rabbit retinas. 1) Under our experimental conditions, the c-wave amplitudes in some rabbits reached equilibrium under intermittent stimuli, while in others they increased with time and did not reach a constant level in 3 h. 2) The c-wave amplitudes of the right and left eyes were similar, indicating that the contralateral eye can be used as a control during local administration of drugs. 3) The c-wave amplitude under 50 lux light had smaller inter-individual variations than that in the dark. This may be a useful indicator of the retinal pigment epithelium function when drugs are administered systemically.

Effects of driving pressure and respiratory rate on airway pressure and PaCO2 in rabbits during high-frequency jet ventilation

The effects of driving pressure (DP) and respiratory rate (RR) on mean airway pressure (Paw), PaCO2, and other respiratory variables were studied during high-frequency jet ventilation (HFJV) in anesthetized rabbits. The animals were tracheotomized and paralyzed, and various combinations of RR (4, 8, 12, and 16 Hz) and DP (0.5, 1.0, and 2.0 kg/cm2) were applied randomly with an inspiratory/expiratory ratio of 1.0. HFJV was delivered via a 2.5-Fr catheter through a T-attachment, using 100% oxygen, and a hot-wire flowmeter was connected to the outlet of the T-attachment for measurement of the minute volume (MV). Heart rate, arterial BP and CVP, respiratory variables, and arterial blood gases were monitored during the study. There were no direct correlations between PaCO2 and DP, MV, or RR. However, there was an inverse correlation between PaCO2 and tidal volume, and linear correlations were found between Paw and DP, and between DP and MV. It is concluded that HFJV over an RR range of 4 to 16 Hz depends mainly upon tidal volume. When the desired PaCO2 and Paw are determined, DP and RR can be calculated following the equations established in this study.

Papillary carcinoma of the pancreas: findings of US and CT

Two cases of papillary carcinoma of the pancreas were evaluated by ultrasound and CT. The sonographic and CT findings were those of a well-defined oval mass with partial cystic change. There was radiologic-pathologic correlation.

Embryonic origins of cells in the leech Helobdella triserialis

To ascertain the embryonic origins of the cells in various tissues of the leech Helobdella triserialis, horseradish peroxidase (HRP) was injected as a cell lineage tracer into all identified blastomeres of the early embryo in turn, except for a few of the micromeres, and the resulting distribution of HRP-labeled cells was then examined in the late embryo. In this way it was found that in every body segment a topographically characteristic set of neurons in the ganglion and body wall and a characteristic territory of the epidermis is derived from each of the four paired ectodermal teloblasts N, O/P, O/P, and Q, whereas the muscles, nephridia, and connective tissue, as well as a few presumptive neurons in each segmental ganglion, are derived from the paired mesodermal teloblast, M. Each topographically characteristic, segmentally iterated set of neurons descended from a given teloblast is designated as a kinship group. However, the prostomial (nonsegmental) epidermis and the neurons of the supraesophageal ganglion were found to be derived from the a, b, c, and d micromere quartet to which the A, B, C, and D blastomeres give rise at the dorsal pole of the embryo. The superficial epithelium of the provisional integument, which covers the surface of the embryo midway through development and is sloughed off at the time of body closure, was found to be derived from the a, b, c, and d micromere quartet, as well as from other micromeres produced in the course of teloblast formation. The contractile fibers of the provisional integument were found to be derived from the paired M teloblast. These results demonstrate that development of the leech embryo proceeds according to a highly stereotyped pattern, in the sense that a particular identifiable blastomere of the early embryo regularly gives rise to a particular set of cells of the adult (or provisional embryonic) tissues.

Vitamin A deficiency and serum or plasma fibronectin in the rat and in human subjects

Fibronectin, a high-molecular-weight glycoprotein occurring in plasma and on the surface of many cells, is involved in cell adhesion and other cell-surface phenomena. Vitamin A deficiency in rats resulted in a threefold increase in the concentration of fibronectin in serum, as measured immunochemically. In vitamin A-depleted human subjects, on the other hand, no correlation could be found between plasma retinol and fibronectin levels.

Effect of inhalational anesthetics on the opioid receptors in the rat brain

Effects of inhalational anesthetics, methoxyflurane and halothane, on the binding of various opioid ligands were studied. The binding affinity of 3H-methionine enkephalin (delta) was reduced by both anesthetics in the same manner, but the receptor density was not significantly affected. Methoxyflurane decreased the binding affinity but increased the receptor density of 3H-dihydromorphine (mu), while halothane had little effects on both affinity and density. Methoxyflurane also decreased binding affinities of 3H-ethylketocyclazocine (kappa) and 3H-SKF-10047 (sigma), but halothane did not decrease significantly. These effects of the anesthetics were completely disappeared by unsealing and ventilation.

A clinical trial with cefoperazone in pneumonia and pyelonephritis

15 cases of pneumonia and 15 cases of pyelonephritis were included in a clinical trial of parenteral cefoperazone. The organisms isolated from patients with bacterial pneumonia were: Staphylococcus aureus (6), Klebsiella pneumoniae (5), Diplococcus pneumoniae (3), Pseudomonas species (2), and 6 others. Amongst those with pyelonephritis, Escherichia coli (12), Enterobacter (1), and 3 other pathogens, were isolated. All were sensitive to cefoperazone. The efficacy of cefoperazone in patients with pneumonia was: good in 11 (73%), fair in 3, and poor in 1. In pyelonephritis, 12 (80%) responded well and in the other 3 response was fair. There were no significant side effects or hypersensitivity reactions.