Hypothesis: etiology of atherosclerosis and osteoporosis: are imbalances in the calciferol endocrine system implicated?

Atherosclerosis and osteoporosis are currently considered unrelated diseases. Osteoporosis involves bone calcium (Ca) loss and predominantly affects females after menopause. Atherosclerosis is an illness predominantly affecting males, and is primarily characterized by abnormal lipid metabolism. However, pathological calcification of the arterial wall is an underlying feature of atherosclerosis. Ca homeostasis is thus important in atherosclerosis as well as in osteoporosis. Men also develop osteoporosis although at a later age than women, and, as osteoporosis progresses in women, there is an accompanying calcification of arteries leading to increased incidence of atherosclerosis in aging women. Thus, during old age, both atherosclerosis and osteoporosis are prevalent in both males and females. The dramatic increase in atherosclerosis among women as they develop osteoporosis suggests that the two illnesses may be more closely related than previously realized. The use of vitamin D as a food supplement coincides with epidemic onsets of atherosclerosis and osteoporosis, and excess vitamin D induces both conditions in humans and laboratory animals. These observations suggest a role for chronic vitamin D excess in the etiology of the two illnesses. Magnesium (Mg) deficiency, nicotine, and high dietary cholesterol are contributing factors that accentuate adverse effects of vitamin D.

HIV protease (HIV PR) inhibitor structure-activity-selectivity, and active site molecular modeling of high affinity Leu [CH(OH)CH2]Val modified viral and nonviral substrate analogs

This report details the structure-activity relationships of the HIV gag substrate analog Val-Ser-Gln-Asn-Leu psi[CH(OH)CH2]Val-Ile-Val (U-85548E), an inhibitor exhibiting subnanomolar affinity towards HIV type-1 aspartic proteinase (HIV-1 PR). Our data show that the P1-P2' tripeptidyl sequence provides the minimal chemical determinant for HIV-1 PR binding. We describe the structure-activity properties of Leu psi[CH(OH)CH2]Val substitution in other peptidyl ligands of nonviral substrate origin (e.g., angiotensinogen, insulin and pepstatin). Furthermore, the aspartic proteinase selectivities of a few key compounds are summarized relative to evaluation against human renin, human pepsin, and the fungal enzyme, rhizopuspepsin. These studies have led to the rational design of nanomolar potent inhibitors of both HIV-1 and HIV-2 PR. Finally, a 2.5 A resolution X-ray crystallographic structure of U-85548E complexed to synthetic HIV-1 PR dimer (Jaskolski et al., Biochemistry 30, 1600 [1991]) provided a 3-D picture of the inhibitor bound to the enzyme active site, and we performed computer-assisted molecular modeling studies to explore the possible binding modes of the above series of Leu psi[CH(OH)CH2]Val substituted HIV-1 PR inhibitors.

Treatment of postcataract fibrinous membranes with tissue plasminogen activator

PURPOSE

The purpose of this study is to investigate the efficacy and toxicity of tissue plasminogen activator (tPA) in treatment of postcataract fibrinous membranes.

METHODS

The authors injected 25 micrograms of tPA into the anterior chamber of 52 pseudophakic eyes with moderate to severe fibrinous membranes that developed after cataract surgery.

RESULTS

Intraocular tPA injection resulted in complete fibrinolysis in 47 of 52 eyes (90%) and partial fibrinolysis in 5 of 52 eyes (10%). In cases of complete fibrinolysis, resolution of the fibrinous membrane occurred within 30 minutes in 22 of 47 eyes (47%) and within 1 hour in 25 of 47 eyes (53%). No evidence of toxicity was observed as measured by slit-lamp biomicroscopy, intraocular pressure, and corneal endothelial cell density, size, and morphology. Complications of tPA administration included periorbital pain (4 eyes), anterior chamber hemorrhage (4 eyes), and anterior chamber turbidity (3 eyes).

CONCLUSION

The authors believe that intraocular tPA is effective and safe in the treatment of postcataract fibrinous membranes.

Desferrioxamine enhances the reactivity of vanadium (IV) and vanadium (V) toward ferri- and ferrocytochrome c

Ligands, especially desferrioxamine, affect the rate at which vanadium reduces or oxidizes cytochrome c. Whether reduction or oxidation occurs, and how fast, depends on the nature of the ligand, the state of reduction of the vanadium, the pH (6.0, 7.0, or 7.4), and the availability of oxygen. In general, oxidation of ferrocytochrome c was favored by (1) low pH, (2) an oxidized state of the vanadium, (3) the presence of oxygen, and (4) more strongly binding ligands (desferrioxamine much greater than histidine = ATP greater than EDTA greater than albumin greater than aquo). Thus, at pH 6.0, desferrioxamine accelerated the V(V)-catalyzed ferrocytochrome c oxidation 160-fold aerobically, and 3500-fold anaerobically. In general, strongly binding ligands slowed oxidations, especially at higher pH. Desferrioxamine was unique among the five ligands in that it not only accelerated oxidation of ferrocytochrome c at pH 6.0, but at pH 7.4 the redox balance shifted to the point where it paradoxically reduced ferricytochrome c. V(V) is an improbable electron donor, but desferrioxamine will reduce cytochrome c, and V(V) accelerates this process. Oxidation of cytochrome c by V(V):desferrioxamine was faster anaerobically, and reduction by V(IV):desferrioxamine was faster aerobically. Although V(V) did not oxidize ferrocytochrome c at pH 7.4, V(IV) did, provided oxygen and desferrioxamine were both present. V(IV):desferrioxamine almost completely reduced ferricytochrome c, and this reduction was followed by a slow, progressive oxidation. This latter oxidation of cytochrome c is mediated by active species generated in the reaction between V(IV):desferrioxamine and oxygen, because none of these reagents alone can induce oxidation at a comparable rate. The mediating species were transient, and generated in reactions with oxygen.(ABSTRACT TRUNCATED AT 250 WORDS)

The influence of nasal patency on accelerometric transduction of nasal bone vibration

The transmission characteristics of nasal tract energy to a nasal accelerometer were evaluated in relation to nasal tract airway resistance. Ten adult speakers repeated three utterances while recordings of nasal bone vibration, as detected by miniature accelerometers, were obtained simultaneously from both sides of the nose and referenced to a common throat signal. Average nasal-to-oral accelerometry ratios recorded from the more resistant side of the nose were significantly larger in magnitude than those recorded simultaneously from the less resistant side of the nose. While accelerometer ratio waveforms from each side of the nose essentially overlapped for some subjects, others displayed unilateral variations in accelerometer output as a function of time. The anatomic and physiologic condition of the nasal passage appears to be an important variable in the detection of nasal tract acoustic energy using the accelerometric technique.

Multiple actions of superoxide dismutase: why can it both inhibit and stimulate reduction of oxygen by hydroquinones?

Superoxide dismutase can either inhibit or stimulate autoxidation of different hydroquinones, suggesting multiple roles for O2.-. Inhibitory actions of superoxide dismutase include termination of O2.(-)-propagated reaction chains and metal chelation by the apoprotein. Together, chelation of metals and termination of O2.(-)-propagated chains can effectively prevent reduction of oxygen. Chain termination by superoxide dismutase can thus account for negligible accumulation of H2O2 without invoking a superoxide:semiquinone oxidoreductase activity for this enzyme. One stimulatory action of superoxide dismutase is to decrease thermodynamic limitations to reduction of oxygen. Whether superoxide dismutase inhibits or accelerates an autoxidation depends on the reduction potentials of the quinone and the availability of metal coordination for inner sphere electron transfers.

Active oxygen in neuromuscular disorders

Although muscle and nerve are reasonably well protected against active oxygen and related free radicals, environmental or inherited malfunctions can overpower their defences. Active oxygen is involved in many neuropathies and myopathies. In every case the damage is caused by agents which exert effects disproportionately greater than the quantities encountered, through a variety of amplification mechanisms. We can categorize these amplification mechanisms as follows: (a) non-replacement of targets (e.g. loss of genetic information, ataxia telangectasia being an hereditary ataxia in which an oxygen mediated chromosomal instability is apparent), (b) non-removal of unwanted materials (e.g. lipofuscin accumulation in brain and heart), (c) redox cycling, usually involving catalysis by trace-metal ions (e.g. some forms of Parkinsonism), (d) non-redox catalysis (e.g. toxicity in cardiac muscle or brain due to vanadium or aluminium respectively), (e) modification of ion transport (e.g. calcium ionophore or acrylamide induce histopathological changes in muscle, similar in some respects to those seen in Duchenne muscular dystrophy), (f) compromised defences (e.g. muscle and nerve become particularly susceptible to free radical damage after loss of the protective actions of vitamin E), and (g) amplification by inflammatory and immune responses (e.g. multiple sclerosis, reperfusion injury to brain and heart, and traumatic injury to nervous tissue). Unfortunately, a variety of therapeutic agents which might be expected to protect against almost every conceivable form of oxygen mediated damage have proved clinically ineffective in most of these disorders. The reasons for this will be explored with an emphasis on common features, differences, mechanisms, and potential therapeutic approaches.

A crossed polaroid-pinhole device

The study describes the use of a pinhole device in which the light-absorbing area surrounding the holes is varied by polarizing filters. The study demonstrates that a pinhole aperture of 1.6-1.8 mm in diameter with polaroids crossed at 90 degrees will allow a visual acuity equal to or better than 20/40 in the face of refractive errors of 1, 2, and 3 diopters. The study next evaluates the effects of pinholes of different sizes and the polarizing components crossed at angles less than 90 degrees. The study concludes by showing that polaroids crossed at between 75 degrees and 85 degrees allow a greater depth of focus, a larger visual field, and greater illumination than traditional pinhole devices.

Bromocriptine and the hypothalamic hypophyseal function in patients with chronic renal failure on chronic hemodialysis

Ten patients with chronic renal failure on chronic hemodialysis had the following tests to evaluate the integrity of the hypothalamic hypophyseal axis: (A) glucose tolerance test, (B) thyrotropin releasing hormone stimulation test, (C) clonidine stimulation test, (D) insulin induced hypoglycemia, and (E) LH/RH stimulation test. The majority of those tests were abnormal and prolactin values were found to be moderately elevated in all the patients. Bromocriptine (1.25 mg twice a day) was given to all the patients for 1 month and then, while on bromocriptine, the tests were repeated. Although there is a decrement in the concentration of serum prolactin level, none of the hypothalamic hypophyseal abnormalities were corrected. However, five of the ten patients reported an improvement of their impotence with bromocriptine. The patients who responded had high levels of FSH and LH with levels of testosterone above 1 mg/mL. The nonresponders had low FSH and LH levels and very low testosterone levels. Therefore, bromocriptine, although possibly beneficial in some dialysis patients, is not a drug that can normalize abnormal functioning of hormones in the dialysis population.

Aerodynamic properties of four tracheoesophageal puncture prostheses

Airway resistance calculations were completed for two tracheoesophageal puncture prostheses (American V. Mueller Blom-Singer Voice Prosthesis and BIVONA Low Resistance Voice Prosthesis), which have recently become available on a commercial basis. These calculations were compared with those made previously for two, existing prostheses: the Blom-Singer duckbill and the Panje Voice Button. Substantial differences in airway resistance properties exist among these four devices. BIVONA Low Resistance devices exhibited the lowest resistance (less than 50 cm H2O/liters per second [LPS]); Panje Voice Buttons exhibited the highest (180 to 200 cm H2O/LPS); and Blom-Singer devices exhibited intermediate values (110 to 125 cm H2O/LPS) of opposition.

A system for slit-lamp polaroid photography

A system is described in which a SX-70, Alpha Model II, Polaroid, single lens reflex camera, and photoflash unit can be quickly and sturdily mounted to a slit lamp. Such a system can take sharp anterior segment prints of the eye at all slit-lamp magnifications, with white light and in the flourescein mode. The heart of the unit is the modification of an assembly initially designed to attach the camera to a light microscope. The small flash unit and power supply were designed specifically for slit lamp usage. Examples of "instant" photos of the anterior segment at different magnifications are presented.

Clinical findings in a case of newly defined gamma heavy chain disease protein

A patient (P.A.R.) is reported with gamma heavy chain disease. The protein differs from previously reported gamma heavy chain disease proteins. The patient's age at disease onset (14 years) and duration of disease (19+ years) also differs from other heavy chain disease patients but are similar to the patient Hi who may have a similar protein. The patients clinical course is reported.