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Biomedical subjects

A Cass

Publications and source records attributed to A Cass.

At least 19 recordsLinked to original sources
PubMed1981

Prenatal diagnosis of fetal urinary tract abnormalities by ultrasound.

The prenatal detection of renal enlargement and sonolucent "cystic" lesions in 4 fetal abdomens by ultrasound is described. These were later proved to be congenital urinary tract anomalies. Only one of the other 4,628 mothers who had ultrasound gave birth to a child with a congenital urinary tract anomaly that was missed, and 1 fetus was falsely diagnosed as having a congenital urinary tract anomaly based on the ultrasound. Obstruction in the developing urinary tract is associated with renal dysplasia and insufficiency. More experience and improved ultrasonography may enable an accurate diagnosis of urinary tract obstruction; and early relief of the obstruction may be a possible method of management to minimize the renal damage.

Abnormalities, Multiple↗
PubMed1979

Necrotizing infection of scrotum.

Necrotizing infection of the scrotum (Fournier gangrene) rapidly spreads to adjacent skin with fever and toxemia and is life-threatening. Subcutaneous gas and a foul-smelling wet discharge from the skin are usually present. The infection is not cured with antibiotic therapy alone and requires immediate extensive debridement of all necrotic tissue. Repeated debridement each several days under general anesthesia is necessary until healthy granulation is present in the wound. Reconstruction with skin flaps or skin grafts shortens hospitalization and prevents the dense scar tissue and immobility of the tests that can occur with spontaneous epithelization.

Adult↗
PubMed1979

Chloride transport by self-exchange and by KCl salt diffusion in gramicidin-treated red blood cells.

The permeability of gramicidin-treated human red blood cell membranes to K+ and Cl- has been measured at normal ionic strength (1) by tracer exchange at steady-state distribution of salt, and (2) by net transport of salt in the presence of a salt concentration gradient. Under both conditions KCl was the only inorganic salt in cells and medium. In the studies of self-exchanges the electrical driving force on the ions was zero. Calculaton of permeability coefficients from net salt transport was simplified because the experiment was designed as a special case of the Nerst-Planck diffusion regime, i.e. the single salt case. Gramicidin altered the cell membranes from being anion to become cation selective. Gramicidin increased the potassium exchange without affecting the chloride exchange measurably. The chloride exchange showed saturation kinetics as does chloride exchange in normal cells. The net transport of KCl in the presence of a constant concentration gradient increased to a constant value with increasing gramicidin concentration. At high gramicidin concentrations (0 degree C, pH 7.2) the "chloride permeability coefficient" calculated from tracer exchange (1.9 x 10(-6) cm/s) was 290 times the chloride permeability coefficient calculated from net salt transport (0.65 x 10(-8) cm/s). The latter value corresponds to a chloride conductance of 4.2 x 10(-6) ohm-1 cm-2. The chloride permeability coefficient was 2.1 x 10(-6) cm/s at 25 degrees C (pH 6.8) indicating a value of 3 for the Q25. It appears that normal red cells are anion selective in the sense that anion permeability exceeds cation permeability with a factor of more than a hundred between 0 degrees C and body temperature. The anion exchange, i.e. the Hamburger shift, is a tightly coupled transport process which is several orders of magnitude faster than anion transport by salt diffusion.

Biological Transport↗
PubMed1978

Acute electrical stimulation for urinary incontinence.

Acute or maximal electric stimulation of the pelvic floor muscles has been used in incontinent patients who are suitable candidates for electrical stimulation, but unwilling or unable to use the anal plug electrodes. Seventeen of 20 patients had relief or improvement of their incontinence. However 5 of these 17 patients had a relapse of symptoms on follow-up, requiring a repeat treatment with acute or maximal electrical stimulation.

Electric Stimulation Therapy↗
PubMed1977

Electrical stimulation of the rectal ampulla causing reflex voiding.

Electrical stimulation of the rectal ampulla resulted in a desire to void and defecate in 11 patients with an intact nervous system. There was a contraction of the detrusor and the rectal ampulla with relaxation of the anal sphincter. Electrical stimulation of the rectal ampulla and anal sphincter has clinical applications in patients with incontinence of, or inability to empty, the lower urinary tract or fecal system.

Anal Canal↗
PubMed1976

Effect of phloretin on the permeability of thin lipid membranes.

Phloretin dramatically increases cation conductances and decreases anion conductances of membranes treated with ion carriers (nonactin, valinomycin, carbonyl-cyanide-m-chlorophenylhydrazone [CCCP], and Hg(C6F5)2) or lipophilic ions (tetraphenylarsonium [tphAs+] and tetraphenylborate [TPhB-]). For example, on phosphatidylethanolamine membranes, 10(-4) M phloretin increases K+ -nonactin and TPhAs+ conductances and decreases CCCP- and TPhB- conductances 10(3)-fold; on lecithin: cholesterol membranes, it increases K+-nonactin conductance 10(5)-fold and decreases CCCP- conductance 10(3)-fold. Similar effects are obtained with p- and m-nitrophenol at 10(-2) M. These effects are produced by the un-ionized form of phloretin and the nitrophenols. We believe that phloretin, which possesses a large dipole moment, adsorbs and orients at the membrane surface to introduce a dipole potential of opposite polarity to the preexisting positive one, thus increasing the partition coefficient of cations into the membrane interior and decreasing the partition coefficient of anions. (Phloretin may also increase the fluidity of cholesterol-containing membranes; this is manifested by its two- to three-fold increase in nonelectrolyte permeability and its asymmetrical effect on cation and anion conductances in cholesterol-containing membranes.) It is possible that pholoretin's inhibition of chloride, urea, and glucose transport in biological membranes results from the effects of these intense intrafacial dipole fields on the translocator(s) of these molecules.

Anti-Bacterial Agents↗
PubMed1970

The ion permeability induced in thin lipid membranes by the polyene antibiotics nystatin and amphotericin B.

Characteristics of nystatin and amphotericin B action on thin (<100 A) lipid membranes are: (a) micromolar amounts increase membrane conductance from 10(-8) to over 10(-2) Omega(-1) cm(-2); (b) such membranes are (non-ideally) anion selective and discriminate among anions on the basis of size; (c) membrane sterol is required for action; (d) antibiotic presence on both sides of membrane strongly favors action; (e) conductance is proportional to a large power of antibiotic concentration; (f) conductance decreases approximately 10(4) times for a 10 degrees C temperature rise; (g) kinetics of antibiotic action are also very temperature sensitive; (h) ion selectivity is pH independent between 3 and 10, but (i) activity is reversibly lost at high pH; (j) methyl ester derivatives are fully active; N-acetyl and N-succinyl derivatives are inactive; (k) current-voltage characteristic is nonlinear when membrane separates nonidentical salt solutions. These characteristics are contrasted with those of valinomycin. Observations (a)-(g) suggest that aggregates of polyene and sterol from opposite sides of the membrane interact to create aqueous pores; these pores are not static, but break up (melt) and reform continuously. Mechanism of anion selectivity is obscure. Observations (h)-(j) suggest-NH(3) (+) is important for activity; it is probably not responsible for selectivity, particularly since four polyene antibiotics, each containing two-NH(3) (+) groups, induce ideal cation selectivity. Possibly the many hydroxyl groups in nystatin and amphotericin B are responsible for anion selectivity. The effects of polyene antibiotics on thin lipid membranes are consistent with their action on biological membranes.

Amphotericin B↗