Blindness impairs plasma growth hormone response to L-dopa but not to arginine

To investigate how blindness influences GH secretion, we studied the GH response to L-dopa and arginine in 8 blind adult males and 10 normal age-matched control males. Arginine and L-dopa tests were performed in random order at least 1 week apart at 0800 h, and plasma GH was measured by RIA. The blind subjects showed GH responses to arginine similar to those in normal subjects [peak, 22.1 +/- 1.3 vs. 20.5 +/- 1.3 micrograms/L (+/- SE)], but their GH response to L-dopa was significantly reduced [peak, 5.4 +/- 1.3 vs. 20.3 +/- 2.4 micrograms/L (+/- SE); P less than 0.01]. Because L-dopa is believed to release GH by stimulating endogenous GHRH, whereas arginine may act by suppressing endogenous somatostatin secretion, we propose that blindness may impair GH release by inhibiting GHRH secretion.

Patterns of pineal melatonin secretion in rabbits: diurnal variation of basal and pulsatile release

The level and release pattern of plasma melatonin in the confluens sinuum of 28 sighted and 18 blinded (i.e. acute bilateral orbital enucleation) rabbits anesthetized with pentobarbital were studied. The animals had been adapted to a 12:12 h light-dark regime. Blood samples were collected from the cannulated confluens sinuum and/or the femoral artery at either 2- or 4-min intervals in both the light and dark phases. Plasma melatonin was determined by radioimmunoassay. In all rabbits studied, plasma melatonin in the confluens sinuum exhibited an episodic release pattern, with pulses superimposed on a basal level. At 4-min sampling intervals, the pulsatile release of melatonin in sighted rabbits were 3.8 peaks/h in the light phase; shorter sampling interval (2-min) revealed more frequent pulsatile release of melatonin (5.1 peaks/h). In sighted animals in the light phase, the level of melatonin in the plasma of confluens sinuum was 7-15 times higher than that obtained from the plasma collected at the same time from the peripheral artery where the level of melatonin also exhibited pulsatile pattern. In blinded animals, melatonin levels in terms of mean concentration, mean maximum level and mean minimum (or baseline) level obtained in the dark phase were 12-14 times higher than those obtained in the light phase. These results suggest that the level of melatonin exhibits a diurnal rhythm in the confluens sinuum of rabbits.

[Clinical findings and trace metals (zinc & copper) in Leber's congenital amaurosis]

Sixteen (16) patients of Leber's congenital amaurosis diagnosed with ERG all had nystagmus since infancy; 9 cases showed the digito-ocular sign and 15 had axial hyperopia on cycloplegic refraction and/or A-scan ultrasonography. The common ophthalmoscopic findings were narrow vessels, grayish coloration and pigmentation in the retina. The average serum zinc level of 12 cases was significantly lower than that of the controls, while the copper level differed not much. The results suggest that it is advisable for the child patients to receive cycloplegic refraction and proper spectacle correction as early as possible, and zinc therapy.

Acute promyelocytic leukemia presenting as sudden blindness and sinus vein thrombosis

An 11-year-old boy was hospitalized with sudden blindness and sagittal sinus vein thrombosis, which were the presenting signs of acute promyelocytic leukemia (APL). The association of disseminated intravascular clotting (DIC) with APL is well-known, and DIC usually affects the smaller blood vessels. The obliteration of a large blood vessel, as in our case, is an uncommon manifestation of DIC. This presentation of acute childhood leukemia is unusual and, to the best of our knowledge, has not been previously reported.

Plasma thyrotropin, thyroxine, triiodothyronine, free thyroxine, free triiodothyronine, and cortisol levels in blind prepubertal boys

Findings on thyroid function in blind subjects are lacking. The aim of this study was to investigate the thyroid hormonal pattern in prepubertal blind subjects. Six healthy and 8 blind males, aged 7-10 yr, in Tanner stage one puberty, living at Institute "Martuscelli" for blind young subjects, Napoli, Italy, were studied. Each had a TRH (200 micrograms) test at 08:00 h after nocturnal rest. Plasma TSH, T4, T3, free T4(FT4), free T3(FT3) and cortisol (F) were measured by RIA. Our blind subjects show levels of TSH (basal values and absolute peak after TRH), T4, T3 and F normal but FT4 levels significantly higher than controls (39 pg/ml +/- 4.7 vs 12 +/- 0.6, p less than 0.001; 14 pg/ml +/- 1.3 vs 4.7 +/- 0.2, p less than 0.001, respectively). Our results, similar to those found in some patients with euthyroid hyperthyroxinemia, suggest that the prolonged inability to receive light signal could influence the metabolism of thyroid hormones and/or cause a tissue resistance to their action, even if this hypothesis must be verified by future more extensive investigations.

Little or no induction of hyperglycemia by 2-deoxy-D-glucose in hereditary blind microphthalmic rats

Studies were made on whether hereditary microphthalmic rats (1), which are congenitally blind, showed a hyperglycemic response to intracerebroventricular injection of 2-deoxy-D-glucose (2DG) in their subjective light period. In contrast to previous findings in normal rats in which 2DG injection caused light-cycle dependent hyperglycemia (2) and bilateral lesion of the suprachiasmatic nucleus (SCN) completely abolished this hyperglycemia (3), 2DG injection caused no and only slight hyperglycemia in male and female rats with hereditary microphthalmia, respectively. Gross and histological examinations indicated that these rats had no optic nerve or retinohypothalamic tract and that their SCN had an abnormal structure. Locomotive activity recordings showed that all the blind rats had a free-running circadian activity rhythm. These findings suggest that the projection sites of the retinohypothalamic tract to the SCN are involved in the mechanism of the hyperglycemic response to 2DG, but that neural cells, which may be responsible for the generation of circadian rhythms, are not. We have reported that when adult rats were blinded by orbital enucleation, their hyperglycemic response to 2DG was suppressed temporarily 3-5 weeks after the operation, but that their plasma insulin level was basically higher and increased further after 2DG injection during this period (4). In congenitally blind rats, however, the basal plasma insulin level was not higher and the level did not change after 2DG treatment. This difference is discussed from the view point of the role of the premature SCN in regulation of the plasma insulin concentration.

Temporary suppression of the hyperglycemic response to 2-deoxy-D-glucose by blinding

Studies were made on whether there is a time-dependency in the hyperglycemic response to intracranial injection of 2-deoxy-D-glucose (2DG) in blind rats. 2DG was given to blind rats in their subjective light and dark periods to see if the response free-runs like their circadian locomotor and feeding rhythms. The following results were obtained: (1) In control period and week 3 after blinding, 2DG caused greater hyperglycemia in the subjective light period than in the subjective dark period; (2) In weeks 4 and 6, however, 2DG caused only slight hyperglycemia, while it caused considerable hyperinsulinemia in both the subjective light and dark periods with no time-dependency. (3) In week 8, the hyperglycemic response to 2DG was completely restored while the hyperinsulinemic response was lost. These findings indicate that the subjective time-dependency in the hyperglycemic response to intracranial injection of 2DG exists until week 3 and after week 8 after blinding, however, in week 4 and 6 after blinding the subjective time-dependency appeared to disappear and the hyperglycemic response is largely suppressed in association with hyperinsulinemia. Together with a previous finding that bilateral lesions of the SCN completely abolished the response to 2DG and the fact that blind rats showed circadian rhythms of feeding and locomotive activity even in weeks 4 and 6 after blinding, these findings present the possibility that the site responding to 2DG is in the vicinity of the SCN, but is in different neuronal cells from those of the circadian oscillator. However, it is also possible that the blinding elicits the suppression of hyperglycemia due to 2DG through disturbing neural pathway outside the SCN which control blood glucose concentration.

Influence of blindness on plasma luteinizing hormone, follicle-stimulating hormone, prolactin, and testosterone levels in prepubertal boys

The aim of this study was to determine if changes in LH, FSH, PRL, and testosterone (T) secretion occur in blind prepubertal boys. Eight blind and six normal boys, aged 7-10 yr, living at an institute for blind subjects in Naples, Italy, were studied. Each had a combined GnRH (100 micrograms) and TRH (200 micrograms) test at 0800 h after nocturnal rest. Plasma LH, FSH, PRL, and T levels were measured by RIA. The blind boys had basal plasma LH, FSH, and T levels significantly lower than those in the normal boys (P less than 0.01 for all three); plasma PRL basal levels were similar to those in the normal boys. The blind boys, moreover, had lower peak LH, FSH, and PRL (P less than 0.01 for all three peaks) levels in response to GnRH-TRH. Our results, similar to those found by others in patients with delayed puberty or with hypogonadotropic hypogonadism, suggest that light stimuli influence neuroendocrine-gonadal activity in humans, as in other mammals; and in blind prepubertal boys, impaired hormone secretion could cause a delay of pubertal development or more severe hypogonadism.

Amaurosis fugax under the age of 40 years

Sixteen patients who presented under the age of 40 years with amaurosis fugax have been studied. Follow up from the time of presentation was one to 13 years with a median of 3 years. One patient whose attacks of uniocular visual loss were associated with headache developed a permanent uniocular field defect. None of the other patients has suffered permanent visual loss, or had symptoms of cerebral or myocardial ischaemia. All angiograms were normal and it is suggested that carotid angiography is unnecessary in this age group. Four out of ten patients studied demonstrated evidence of platelet hyperaggregability to low concentrations of arachidonic acid and adenosine diphosphate with spontaneous aggregation. However, in six patients treated with aspirin, including three with previous platelet hyperaggregability, there was no change in the frequency of their attacks implying that the observed platelet abnormalities were not the cause of the amaurosis fugax.

Leber's congenital amaurosis associated with hyperthreoninemia

Two siblings had Leber's congenital amaurosis. The girl (Patient 1) showed blindness shortly after birth, absent pupillary light reflex, and multiple round, white spots in both fundi. Her serum threonine level was increased (2.0 to 5.3 mg/dl; normal, 0.78 to 1.82 mg/dl). She died of massive pericardial effusion four months after birth. Her brother (Patient 2) was nearly blind shortly after birth. He had a poor pupillary light reflex and a nearly extinguished electroretinographic response. He also had hyperthreoninemia, hyperthreoninuria, hepatomegaly, and mental and physical retardation. We suspect a close relationship between hyperthreoninemia and Leber's congenital amaurosis in these siblings.

The influence of blinding, olfactory bulbectomy, and pinealectomy on twenty four-hour plasma prolactin levels in normal and neonatally androgenized female rats

The influence of blinding (BLD), olfactory bulbectomy (ANOS), and pinealectomy (PX) on 24-h plasma PRL levels was examined in normal and neonatally androgenized (NA) female rats. NA pups were treated at 3 days of age with 1.25 mg testosterone propionate. Surgery was performed on both NA and normal animals at 22-25 days of age. At 10 weeks of age, animals were vaginally smeared, and at 15 weeks, they were ovariectomized, injected with 0.5 mg polyestradiol phosphate, and fitted with atrial catheters for blood sampling. At 16 weeks of age, blood samples were taken over a 24-h period. In normal animals, BLD plus ANOS resulted in half of the animals exhibiting a diestrous vaginal smear, while the other half exhibited at least one vaginal estrus during the 7-day period when vaginal smears were obtained. Ovarian, oviductal, and uterine weights for blinded (BLD) plus olfactory bulbectomized (ANOS) animals exhibiting diestrous smears were significantly less than those of BLD plus ANOS animals exhibiting periodic vaginal estrus. Plasma PRL levels were lower in both animal groups compared with those in sham controls, but BLD plus ANOS animals with small ovaries had significantly lower plasma PRL and BLD plus ANOS animals with large ovaries. PX of BLD plus ANOS animals resulted in endocrine organ weights comparable to those in controls and elevated the plasma PRL levels to those observed in BLD plus ANOS animals with large ovaries. The PRL levels in BLD, ANOS, and pinealectomized animals, however, were still below those in sham control animals. Sensory deprived animals had peak PRL values at various times of day, and regrouping of the data from the peak PRL time for each animal suggested the presence of a free-running plasma PRL rhythm. In NA animals, a decrease was also observed in endocrine organ weights and plasma PRL for BLD plus ANOS animals similar to that observed for normal BLD plus ANOS animals. However, all animals in the NA BLD plus ANOS group responded with a constant diestrous smear, small ovaries, and low plasma PRL values. PX prevented the decrease in endocrine organ weights and plasma PRL observed in BLD plus ANOS animals. As in normal animals, NA animals also exhibited a free-running PRL rhythm when sensory deprived.(ABSTRACT TRUNCATED AT 400 WORDS)

Use of tactile techniques for self-monitoring of blood glucose in visually impaired patients with diabetes mellitus

Twenty-eight patients with type I diabetes mellitus, legally blind as a result of proliferative retinopathy, were recruited into a program designed to teach and evaluate tactile methods for self-monitoring of blood glucose (SMBG). Vision ranged from "blind" to "able to read large print." Techniques with wipe-off strips (Chemstrip bG or BM Test BG, Boehringer-Mannheim, Canada Ltd., Dorval, Quebec, Canada) use the opposite hand as a guide, operation of timing devices by touch, and special methods for labeling and storing strips. Methods with wash-off strips (Dextrostix, Ames Division, Miles Laboratories, Rexdale, Ontario, Canada) employ the fingers as a guide in directing the wash water. The accuracy of tactile methods was documented. Clinical parameters of glucose control improved in patients with adequate data after 6 mo of tactile SMBG. Glycosylated hemoglobin in 17 patients decreased from 11.3 +/- 2.1% to 9.4 +/- 1.5% (P = 0.005). Patients experienced significantly fewer reactions and low blood sugar readings as well as lowering of mean blood glucose values from 158 +/- 56 to 141 +/- 51 (P = 0.025).

Coincidence of counter-antigonadal and counter-antithyroid action of melatonin administration via the drinking water in male golden hamsters

Administration of melatonin via the drinking water prevented the gonadal involution and the thyroid hormone depletion normally observed in blinded hamsters. Ten weeks after blinding male hamsters had plasma thyroxin levels that were 57% of controls and testis weights that were 8% of controls. Administration of melatonin (80 microgram melatonin/ml drinking water) to blinded hamsters restored thyroxin levels to 86% of controls and testis weights to 93% of controls. Dose response data showed that as little as 1.25 microgram (approximately 10 microgram/hamster/day) produced a significant effect on testis weight, whereas the lowest dose required to produce a significant increase in thyroxin levels was 10 microgram/ml. The coincidence of counter-antigonadal and counter-antithyroid actions of melatonin suggests a single site of action.

Entrainment of the circadian rhythms of blinded infant rats by nursing mothers

New-born rats were optically enucleated on day 1 and the rhythms of pineal serotonin N-acetyltransferase activity and serum corticosterone levels were followed under various nursing schedules from 4 to 8 weeks of ages. When blinded pups born under DL (LD) cycle were reared by foster mothers under LD (DL) cycle, both of N-acetyltransferase and corticosterone rhythms were in phase with those of the pups born of and reared by their original mothers under LD (DL) cycle. The phases of the rhythms were regularly delayed at a similar rate in 4 groups as they grew, indicating that nursing mother rats can entrain the circadian rhythms of blinded pups. When intact and blinded pups were reared under LD cycle, the phases of N-acetyltransferase activity rhythm in both groups were identical at the first postnatal week, but the phase of the rhythm in blinded pups was gradually delayed after second week compared to intact pups. The observation indicates that the endogenous oscillation in blinded pups starts to free-run between 1 and 2 weeks after birth.

Effects of light on human melatonin production and the human circadian system

Bright artificial light appears to have similar effects in humans as in other species. Bright light may therefore be used as a clinical research tool and as a therapeutic modality for treating certain biological rhythm disorders. Melatonin production appears to be a particularly useful "biological marker" for the human endogenous circadian pacemaker and the effects of light.

Effects of change of mothers and lighting conditions on the development of the circadian adrenocortical rhythm in blinded rat pups

Free-running blood corticosterone rhythms were examined between the 4th and 9th postnatal week in blinded rat pups optically enucleated on day 1. The pups were born of mother rats having a free-running rhythm under constant illumination conditions and then were put under two separate illumination conditions (light - dark cycle and dark - light cycle) under the care of foster mothers already synchronized to each respective condition. Despite being born of the same mother rat, when the pups were raised by a mother with a different rhythm from that of the natural mother, they showed a different phase from that of the pups raised by the natural mother. Furthermore, each possessed different phase angles, depending on the rhythm of their respective foster mothers. On the other hand, although the rhythm of the natural mothers differed, when the rhythms of the nursing mothers were the same after birth, the blinded pups showed similar phase angles during the observation periods. These data suggested that the blinded pups were not affected by the rhythm of the natural mothers but rather showed a phase angle in accordance with the rhythm of the nursing mother.

Changes in serum prolactin following binding and constant light exposure

The effects of blinding and constant light exposure for 5 weeks on serum concentrations of prolactin were studied in male rats. Neither treatment had any effect on body, pineal, pituitary, testis, or seminal vesicle weights. Serum prolactin was not significantly altered by constant light exposure, but was significantly elevated by blinding. These data provide further support that prolactin secretion is elevated by blinding. It is suggested that prolactin may be partially responsible for the lack of significant gonadal atrophy following blinding in male rats.

Complement-induced vascular leukostasis. Its role in tissue injury

The plasma complement system evolved as a beneficial antimicrobial mechanism. However, this system can be activated chaotically in such situations as extracorporeal perfusion, trauma, sepsis, or acute pancreatitis. When so activated, the complement component C5a may aggregate granulocytes and cause leukoembolization; it is suggested that such leukoembolization is an important, previously unsuspected mechanism of tissue damage. In addition, toxic oxygen species, such as superoxide, that are produced by granulocytes that have been triggered by C5a can damage the endothelium, an event that may, if it occurs in the lungs, contribute to the development of the adult respiratory distress syndrome (ARDS). Hence the previously empiric use of high doses of corticosteroids in treating shock states, particularly in cases of the ARDS, may have a physiologic basis since very high concentrations of such drugs have been shown to inhibit both superoxide production and granulocyte aggregation.

Demonstration of pathological circulating endothelial cells in patients with amaurosis fugax

The present study was performed in nine patients with amaurosis fugax (AF). Eight of the patients had had at least one attack of AF in the preceding 3 months, and the ninth, a woman aged 35 years, had also had a transient cerebral ischaemic attack (TIA) 5 months previously, with residual hemiparesis. Only one patient, a man aged 51 years, had been given 'anti-platelet' therapy before beginning this study, having had a mycocardial infarct some years before. We suggest that AF is due to an embolism of platelet aggregates in the ophthalmic artery and that it is damage to the vascular endothelium which induces the platelet aggregation. In this study, we demonstrate by a simple technique an increased level of abnormal circulating endothelial cells in patients with AF.

[Amaurosis fungax. Studies on hemodynamics and platelet function]

Thirty-eight patients with amaurosis fugax were examined ophthalmologically. In 12 of these cases carotid occlusion was diagnosed by ophthalmodynamography and Doppler ultrasonography of the orbital vessels. Angiographic substantiation was possible in nine of these patients. The pathognomonic importance of amaurosis fugax for occlusive carotid disease is clearly shown by these findings. The plasma concentration of platelet specific proteins was examined in 32 patients and found to be pathologically increased in 13 cases. Spontaneous aggregation of platelets and circulating platelet aggregates were only found in a few patients. Due to the lack of coincidence between the event of amaurosis fugax and the time when platelet function tests were made no definite conclusions may be drawn from these results. Yet disturbances of platelet function must be taken into consideration in the pathogenesis of amaurosis fugax.

The rate of phase shift of plasma corticosterone circadian rhythm during early developmental stages in neonatally blinded rats

The phase shift of circadian periodicity of pituitary-adrenocortical activity was studied in neonatally blinded infant rats. The phase shift of the rhythm was surprisingly rapid during the early stage of prepubertal period, while changes in the rhythm pattern were rather small after puberty, as indicated by a slight shift of the acrophase. Low amplitude was observed in the group data of blinded rats after puberty.