Rilmenidine-induced ocular hypotension: role of imidazoline1 and alpha 2 receptors

PURPOSE

To examine ocular actions by rilmenidine, an imidazoline1 and alpha 2 adrenoceptor agonist.

METHODS

Intraocular pressure was measured in normal and sympathetically denervated rabbits by pneumatonometry. Electrically stimulated 3H-norepinephrine release from sympathetic nerves was determined in isolated, perfused rabbit iris-ciliary bodies. cAMP levels were evaluated in rabbit iris-ciliary bodies by radioimmunoassay. Ca2+ concentrations were measured in rabbit transformed nonpigmented ciliary epithelial cells by fluorescence ratio microscopy.

RESULTS

Topical, unilateral administration of rilmenidine produced hypotensive responses in normal rabbits which were antagonized by either bilaterally administered efaroxan, an imidazoline receptor antagonist or rauwolscine, an alpha 2 receptor antagonist. Sympathectomy also eliminated the ocular hypotensive response. Rilmenidine (0.001, 0.01, 0.1, 1 microM) caused 5 +/- 1%, 18 +/- 5%, 35 +/- 10%, and 48 +/- 9% inhibition, respectively, of 3H-norepinephrine overflow whereas 10 microM efaroxan or rauwolscine caused enhancement of norepinephrine release by 102 +/- 23% or 86 +/- 25%, respectively. Furthermore, pretreatment with efaroxan or rauwolscine partially antagonized the inhibition of norepinephrine release induced by rilmenidine. In other experiments, rilmenidine (1 microM) inhibited isoproterenol-stimulated cAMP accumulation in rabbit iris-ciliary bodies by 43 +/- 9% which was antagonized by 10 microM efaroxan or rauwolscine. Rilmenidine induced large increases in [Ca2+]i in rabbit nonpigmented ciliary epithelial cells which were effectively antagonized by efaroxan or rauwolscine.

CONCLUSIONS

These in vivo and in vitro data suggest that the ocular hypotensive activity induced by rilmenidine is due, in part, to suppression of sympathetic neuroeffector function in the rabbit ciliary body and that alpha 2 adrenergic receptors and/or imidazoline1 receptors are involved.

A case of neonatal Bartter's syndrome

We describe a child with a neonatal presentation of Bartter's syndrome. Unlike infants previously described with a similar clinical presentation, the urinary excretion rate of prostaglandin E2 in this child was similar to normal children and Tamm-Horsfall protein was distributed normally in the thick ascending limb of the loop of Henle. The child failed to respond to indomethacin alone, but thrived after the addition of the angiotensin converting enzyme inhibitor, captopril.

Design and synthesis of C-linked fucosides as inhibitors of E-selectin

Two series of C-linked fucosides as mimetics for the tetrasaccharide sialyl Lewis X have been synthesized and tested as inhibitors of E-Selectin. The fucopeptides have been prepared from three key intermediates, including alpha-C-allyl fucose, natural and unnatural amino acids bearing hydroxyl groups and an alpha, omega-diacid moiety for the imitation of the essential three parts of SLex, i.e., the Fuc, Gal, and NeuAc. The nature and distance of the linkage of the fucose moiety to the amino acids as well as the distance between the amino acids and the terminal carboxylic acid group turned out to be crucial for the biological activity. In addition the necessity of both OH groups (4- and 6-OH) in the Gal part could be confirmed. Conformational NMR study of the most active mimetic supports the structure-activity relationship. A second series of mimetics was prepared, where Fuc and Gal moieties were purely C-linked. In the synthesis of beta-C-allyl galactose an intramolecular 1,2-hydride shift led to an interesting side product. However, the substituted glycosidic oxygens led to a substantial loss of conformational constrain, which could not be compensated and resulted in low activity.

Fatal haemorrhagic gastritis associated with oral sulindac treatment for patent ductus arteriosus

We report the first case in a preterm infant given oral sulindac for treatment of symptomatic patent ductus arteriosus who subsequently developed severe acute haemorrhagic gastritis leading to disseminated intravascular coagulation, massive pulmonary haemorrhage and death. The postmortem examination suggested that the mechanism was likely a direct irritant insult causing ischaemia on the gastric mucosa. Although sulindac is supposed to be a renal-sparing non-steroidal anti-inflammatory prodrug associated with minimal renal and gastrointestinal adverse effects, clinicians should be alerted to this potential life-threatening complication in preterm infants. Until the question of safety could be adequately addressed, the use of sulindac for ductal closure should remain experimental.

Neuroimaging characteristics in carbon monoxide toxicity

Neuroimaging studies for 18 patients carrying carbon monoxide toxicity as a discharge diagnosis were reviewed. The most common positive findings were low-density lesions in the globus pallidus (7/18, 39%) and deep white matter changes (5/18, 28%). Six computed tomography head scans showed no acute changes. Advanced age, method of exposure (intentional vs accidental), and severity of carboxyhemoglobin level did not predict neuroradiological or clinical outcomes. Early neuroimaging could not be used to predict clinical courses (death or coma vs discharge to either an institution or a home) in the patient population studied.

Varicella exposure in a neonatal intensive care unit: emergency management and control measures

We describe an exposure of varicella zoster virus in our neonatal intensive-care unit and the emergency procedures instituted to prevent an outbreak. Fifty-seven infants and 129 staff members were exposed but none developed chickenpox. The measures included rapid identification of varicella antibody status in all neonates and those staff members with uncertain history of varicella infection; cohorting of exposed infants according to immune status; and prompt administration of varicella zoster immunoglobulin to susceptible patients. The recommendation of the American Academy of Pediatrics did not accurately predict the immune status of preterm infants, as only one of the eight susceptible infants would have qualified for immunoglobulin prophylaxis if their guidelines had been followed. Mass screening of all exposed infants using the varicella zoster enzyme linked immunosorbent assay (ELISA) test was the only reliable means of determining the immune status. Of the four risk factors evaluated for the prediction of antibody status: gestational age, postnatal age, birthweight and episodes of blood transfusion, only postnatal age was found to independently predict the immune status of our patients. Because varicella zoster susceptible staff members are difficult to identify on the basis of history, we suggest that prospective screening of staff in high-risk units be undertaken and vaccination with live varicella vaccine be offered to susceptibles.

Transplant renal artery stenosis in 77 patients--does it have an immunological cause?

Transplant renal artery stenosis (TRAS) is a common complication after transplantation and is an important cause of graft dysfunction. Damage from graft rejection, trauma, and atherosclerosis have been implicated as possible causes. We reviewed all 917 patients transplanted in our unit since 1978 to study the prevalence, clinical features, and possible causes of TRAS. Seventy-seven patients with TRAS were identified. The detected incidence was 2.4% before the introduction of color doppler ultrasonography (CDU) and rose to 12.4% after CDU was introduced in 1985, giving an overall incidence of 8.4% during a mean follow-up period of 6.9 years. The TRAS group was compared with a control group of 77 transplanted patients matched for age, year of transplant, sex, and number of previous grafts. Mean ages for the study and control groups were 43.6 +/- 15 and 44.8 +/- 13.7 yr. A total of 25% of cases of TRAS were diagnosed within the first 8 wk of transplantation and in 60% within the first 30 wk (median = 23 wk). All patients were treated with angioplasty, 28 patients had recurrence of TRAS requiring multiple angioplasties (maximum 5) and 1 went on to have surgery. Angioplasty resulted in a significant fall in plasma creatinine. Patient and graft survival were significantly worse in the TRAS group: 69% vs. 83% (P < 0.05) and 56% vs. 74% (P < 0.05) (TRAS vs. Control), respectively. There was a significantly higher incidence of rejection, especially cellular rejection in the TRAS group, 0.67 vs. 0.35 episodes per patient (P < 0.01) (TRAS vs. Control). Recurrence but not occurrence of TRAS was associated with the use of cyclosporine.

Use of eyepatches in phototherapy: effects on conjunctival bacterial pathogens and conjunctivitis

We conducted a randomized controlled trial to determine the effects of eye occlusion on the risk of eye infection in full term newborn infants receiving phototherapy. Among 102 infants whose eyes were occluded with eyepatches, pathogens were isolated from 50 eyes of 33 infants. The positive isolation rate was significantly higher than that of a group of control infants (n = 101) whose eyes were protected by a headbox made of light-proof plastics. Among the latter group pathogens were detected in 22 eyes of 14 infants. In addition significantly more infants in the eyepatches group had purulent eye discharge (23 of 102 vs. 9 of 101, P = 0.013) and clinical conjunctivitis (13 of 102 vs. 2 of 101, P = 0.004) than the controls. Proper eye care is imperative when eyepatches are used on infants receiving phototherapy, and alternative methods of eye protection should be considered.

Bacterial contaminated breast milk and necrotizing enterocolitis in preterm twins

A pair of preterm twins developed fatal necrotizing enterocolitis (NEC) in association with Staphylococcus epidermidis septicaemia after receiving contaminated expressed breast milk (EBM). S. epidermidis NEC can be associated with severe bowel inflammation, high morbidity and mortality. Breast milk is the most suitable nutrient for preterm infants but EBM should undergo regular screening for bacterial overgrowth. We urge caution before administering EBM found to be heavily contaminated with S. epidermidis to preterm infants.

High frequency oscillatory ventilation in newborns with idiopathic persistent pulmonary hypertension

Three consecutive term infants diagnosed as suffering from idiopathic persistent pulmonary hypertension of the newborn (PPHN) were tried on high frequency oscillatory ventilation (HFOV) after failure of conventional mechanical ventilation (CMV). All experienced a significant improvement in oxygenation. All three infants survived. HFOV was utilised in a fourth term infant initially diagnosed as having idiopathic PPHN with an immediate benefit. This infant subsequently died and was found at autopsy to have a lethal congenital maldevelopment of pulmonary microcirculation. No serious adverse effects were encountered with HFOV in contrast to the use of pharmacologic agents where hypotension was a serious problem. A therapeutic trial of HFOV is simple and efficient, and would not cause undue delay in the commencement of other rescue therapy should it prove unsuccessful. We predict HFOV will replace non-specific vasoactive agents as the standard first line alternative to CMV for the treatment of idiopathic PPHN.

A sparse matrix screen to establish initial conditions for protein renaturation

Protein renaturation is of particular interest not only for the basic mechanisms of protein folding but also as a practical problem for proteins overexpressed in microorganisms, since recombinant proteins may accumulate as misfolded aggregates in "inclusion bodies" that are inactive after purification. We have established a systematic screening method to identify conditions which promote protein renaturation. A matrix of 50 different buffers, which were originally developed for protein crystallization, were found to facilitate the renaturation for eight of nine different proteins examined. The proteins tested include the adhesive protein bindin, recombinant bindin, and a variety of enzymes, including bacterial alkaline phophatase, horseradish peroxidase, lysozyme, trypsin, beta-galactosidase, rabbit carboxylesterase, and acetylcholinesterase. The total amount of activity recovered varied from 9 to 333% depending on the protein. The conditions that were found to promote renaturation are very different from the optimal conditions for enzyme activity. The finding that most of the proteins tested renatured to a significant extent in one or more of the buffers in the matrix suggests that the sparse matrix screen may be of general utility for establishing initial renaturation conditions for a wide variety of proteins. One initial renaturation conditions have been identified, the conditions may be optimized by systematically altering other parameters of the renaturation process.

Isolated congenital tuberculosis otitis in a preterm infant

We report an unusual case of localized congenital tuberculosis otitis in a preterm infant. Unlike disseminated congenital cases, the manifestations of localized otitis are associated with a triad of signs: (i) regional lymphadenopathy in the absence of typical systemic features of tuberculosis; (ii) delayed onset of presentation; and (iii) refractory otitis unresponsive to conventional antimicrobial agents. The need for greater diligence in looking for neonatal tuberculosis is emphasized, especially in an ethnic or socioeconomic environment where the disease is prevalent.

Conservative surgery and adjuvant radiation therapy in the management of adult soft tissue sarcoma of the extremities: clinical and radiobiological results

PURPOSE

The outcome of adult patients with soft tissue sarcoma of the extremities treated with conservative surgery and adjuvant irradiation was evaluated to (a) determine the appropriate treatment volume and radiation dosage in the postoperative setting, and (b) correlate in vitro radiobiological parameters obtained prior to therapy with clinical outcome.

METHODS AND MATERIALS

Sixty-four consecutive adult patients with soft tissue sarcoma of the extremities (40 lower, 24 upper) who underwent conservative surgery and adjuvant irradiation 7 preoperative, 50 postoperative, 7 perioperative) between 1978 and 1991 were reviewed. The initial radiation field margin surrounding the tumor bed/scar was retrospectively analyzed in all postoperative patients. Initial field margins were < 5 cm in 12 patients, 5-9.9 cm in 32 and > or = 10 cm in 6. Patients with negative pathological margins were initially treated with traditional postoperative doses (64-66 Gy); however, in later years the postoperative dose was reduced to 60 Gy. Thirteen cell lines were established prior to definite therapy, and radiobiological parameters (multitarget and linear-quadratic) were obtained and correlated with outcome.

RESULTS

Postoperative patients treated with an initial field margin of < 5 cm had a 5-year local control of 30.4% vs. 93.2% in patients treated with an initial margin of > or = 5 cm (p = 0.0003). Five-year local control rates were similar in patients treated with initial field margins of 5-9.9 cm (91.6%) compared with those treated with > or = 10 cm margins (100%) (p = 0.49). While postoperative patients receiving < 60 Gy had a worse local control than those receiving > or = 60 Gy (p = 0.08), no difference was seen in local control between patients receiving less than traditional postoperative doses (60-63.9 Gy) (74.4% vs. those receiving 64-66 Gy (87.0%) (p = 0.5). The local control of patients treated in the later years of the study, with strict attention to surgical and radiotherapeutic technique, was 87.6%. Severe late sequelae were more frequent in patients treated with doses > or = 63 Gy compared to patients treated with lower doses (23.1% vs. 0%) (p < 0.05). Mean values for Do, alpha, beta, D, n and SF2 obtained from the 13 cell lines were 115.7, 0.66, 0.029, 2.15, 0.262, respectively. Four of the 13 cell lines established prior to therapy ultimately failed locally. The radiobiological parameters of these cell lines were similar to the other nine cell lines in terms of radiosensitivity.

CONCLUSIONS

Our data confirm the importance of maintaining an initial field margin of at least 5 cm around the tumor bed/scar in the postoperative setting. No benefit was seen with the use of margins > or = 10 cm. In addition, patients undergoing wide local excision with negative margins can be treated with lower than traditional postoperative doses (60 Gy) without compromising local control and with fewer chronic sequelae. Finally, it does not appear that inherent tumor cell sensitivity is a major determinant of local failure following radiation therapy and conservative surgery in soft tissue sarcoma.

Determination of CD4 and CD8 lymphocyte subsets by a new alternative fluorescence immunoassay

The purpose of this study was to evaluate a new alternative fluorescence immunoassay method (Zymmune CD4/CD8 Cell Monitoring Kit; Zynaxis, Inc., Malvern, Pa.) for determining the absolute CD4+ and CD8+ T-lymphocyte concentrations in whole blood. The investigation was performed as a two-site comparison of the reference whole blood flow cytometric method with the Zymmune method. In this investigation, a total of 166 patient samples were evaluated of which approximately 20% were from human immunodeficiency virus-positive individuals. The mean value for samples performed by the Zymmune CD4 assay was 1,094 (range, 74 to 2,586) cells per microliters, while the reference method yielded a mean of 890 (range, 35 to 2,033) cells per microliter. The correlation coefficient for regression analysis was 0.940. The mean value for samples performed by the Zymmune CD8 assay was 700 (range, 212 to 1,813) cells per microliter, while the reference method yielded a mean of 546 (range, 82 to 2,158) cells per microliter. The correlation coefficient for regression analysis was 0.921. No site-specific differences or trends in CD4 or CD8 values were seen when the data were analyzed by site of collection. The average precision of the CD4 assay varied from 6 to 14%, corresponding to the high and low concentration ranges. For CD8, the average precision varied from 8.3 to 16% over the respective high to low concentration ranges. We conclude that the Zymmune CD4/CD8 Cell Monitoring Kit method provides absolute CD4+ and CD8+ T-lymphocyte concentrations which are equivalent to those given by the reference flow cytometric method.

Congenital misalignment of pulmonary vessels: an unusual syndrome associated with PPHN

We report a case of misalignment of pulmonary vessels and review the clinical features of all 13 cases reported to date. All were term infants dying from severe persistent pulmonary hypertension of the newborn. We have identified a triad of features that will alert neonatal clinicians to the possibility of this diagnosis: association with other non-lethal congenital malformations; delayed onset of presentation (especially after 12h); and severe hypoxaemia refractory to conventional therapy. We recommend that any autopsy on newborn infants include a specific search for misalignment of pulmonary vessels to outline the pathophysiology and clinical significance of this disorder.

A universal model of single-unit sensory receptor action

We present a model governing the operation of all "isolated" sensory receptors with their primary afferent neurons. The input to the system is the intensity of a sensory signal, be it chemical, optical etc., and the output is the rate of neural impulse transmission in the afferent neuron. The model is based on the premise that information is conserved when transmitted by an efficient sensory channel. Earlier studies on this informational or entropic model of receptor function were constrained to the cases where the sensory stimulus assumed the form of an infinite step function. The theory was quite successful in treating mathematically all responses to such elementary sensory stimuli--both neural, and by extension, psychophysical. For example, the theory unified the logarithmic and power laws of sensation. However, the earlier model was incapable of predicting responses to time-varying stimuli. The generalized model, which we present here, accounts for both steady and time-varying signals. We show that more intense stimuli are remembered by sensory receptors for longer periods of time than are less intense stimuli.

Acute basal ganglia infarction in propionic acidemia

An 8-year-old girl with propionic acidemia had acute and rapidly fatal symmetric necrosis of the caudate, globus pallidus, and putamen. Clinical presentation was with acute aphasia, generalized hypotonia, and muscle weakness. There was no evidence of metabolic decompensation, and analysis of the organic acids of the urine indicated good metabolic control. Organic acids in the cerebrospinal fluid were unremarkable. These observations indicate that the pathophysiology of "metabolic stroke" is more complicated than previously thought.

Injustice in family care of the Chinese elderly in Hong Kong

With increasing longevity, family care of the Chinese elderly in Hong Kong is evolving as a "caring trap" for female caregivers, especially unmarried daughters. Despite this, as Hong Kong is still a patriarchal Chinese society, most of the major decisions affecting the destiny of frail elders are made by sons or other male members of the family. The unequal gender roles, obligations, and division of caregiving responsibilities within the Chinese family and their effects on the caring relationship are discussed. Implications of this injustice based on gender regarding family care of the elderly and the possibility of its elimination are examined.

Congenital Candida pneumonia in a preterm infant

A 24 week gestation survivor of congenital Candida pneumonia who received prompt antifungal treatment and modern neonatal intensive care is reported. It was an unusual case in that fungal chorioamnionitis occurred without a foreign body in the maternal genital tract. Early diagnosis and treatment of congenital fungal pneumonia was possible because of prior knowledge of the obstetric history. Amphotericin B was successfully used for the treatment of this condition but combination with fluconazole (a fungistatic agent) was unsatisfactory and may be undesirable. Dexamethasone therapy to assist extubation was instituted once the fungal infection had been successfully controlled.

[The in vitro potentiation of LAK cell cytotoxicity in cancer and aids patients induced by F3--a fractionated extract of Astragalus membranaceus]

The in vitro induction of LAK cell activity was studied in cancer and AIDS patients. F3, an immuno-regulatory component of Astragalus membranaceus was shown capable of potentiating the LAK cell inducing activity of rIL-2. The killing activity against Hs294T melanoma cell line of LAK cells induced by 50 U/ml rIL-2 in the presence of F3 (55 micrograms/ml) reached 64% which was comparable to that (60%) induced by 500 u/ml of rIL-2 alone. With F3 plus rIL-2, the effector to target cell ratio could be reduced to one-half in order to obtain an equivalent level of cytotoxicity when rIL-2 was used alone. In some patients, whose peripheral blood lymphocytes were relatively inert to rIL-2, F3 could make them responsive to rIL-2. These results imply that F3 may be useful to potentiate LAK cell activity, reduce the amount of rIL-2 and thus minimize the later's toxic side effects when used in vivo.

Audit on Myocardial Infarction in a District General Hospital: Is There Room for Improvement in Diagnostic Accuracy?

The proportion of patients with an acute myocardial infarction (MI) whose diagnosis was missed on admission was accessed. The admitting consultants were then tested to see if they could diagnose the patients correctly when they were shown the admission histories and electrocardiograms (ECGs).

Twenty-six per cent of patients with a final diagnosis of MI were not correctly diagnosed on admission. Fifty-one per cent of all patients did not receive thrombolytic therapy (TT) mainly because the diagnosis was not made on admission. A smaller proportion of these patients were admitted to the coronary care unit (CCU).

The consultants only correctly diagnosed an average of 7.3 of the 20 patients who were mis-diagnosed on admission and would have prescribed TT to an average of 4.3 of these 20 patients.

A significant proportion of patients had a diagnosis of MI missed on admission and therefore did not receive TT. Therefore, another aid to diagnosis such as serum creatinine phosphokinase (CPK) measurement should be available as an emergency test.

Ultraviolet transmittance of contact lenses

Chronic and acute exposure to ultraviolet (UV) radiation has been shown to have deleterious effects on all layers of the human eye. As a consequence, appropriate protective measures have been advocated with respect to exposure to this form of radiation. Among suggested actions are spending less time in the sun and wearing protective visual aids such as those containing UV-absorbing materials when exposed to sunlight. To investigate the protective ability of currently available contact lens materials we measured the transmittance characteristics of 11 different types of soft and rigid contact lenses in the UV and visible range from 280 to 500 nm with a Zeiss model DM4 Dual Beam Spectrophotometer. Our findings indicate that lenses not treated with UV absorbers transmitted most of the UV radiation. Lenses containing UV absorbers provided excellent UV protection and transmitted significantly less UV radiation than the untreated lenses (Student's t-test with Bonferoni's correction, N = 10, p < 0.001). Based on our findings, we recommend that contact lenses with UV absorbers be considered as a viable option for providing UV protection, especially for aphakic patients, patients taking photosensitizing pharmaceutical agents, and those patients who spend a great deal of time outdoors.