The human Descemet's membrane and lens capsule: Protein composition and biomechanical properties.

The Descemet's membrane (DM) and the lens capsule (LC) are two ocular basement membranes (BMs) that are essential in maintaining stability and structure of the cornea and lens. In this study, we investigated the proteomes and biomechanical properties of these two materials to uncover common and unique properties. We also screened for possible protein changes during diabetes. LC-MS/MS was used to determine the proteomes of both BMs. Biomechanical measurements were conducted by atomic force microscopy (AFM) in force spectroscopy mode, and complemented with immunofluorescence microscopy. Proteome analysis showed that all six existing collagen IV chains represent 70% of all LC-protein, and are thus the dominant components of the LC. The DM on the other hand is predominantly composed of a single protein, TGF-induced protein, which accounted for around 50% of all DM-protein. Four collagen IV-family members in DM accounted for only 10% of the DM protein. Unlike the retinal vascular BMs, the LC and DM do not undergo significant changes in their protein compositions during diabetes. Nanomechanical measurements showed that the endothelial/epithelial sides of both BMs are stiffer than their respective stromal/anterior-chamber sides, and both endothelial and stromal sides of the DM were stiffer than the epithelial and anterior-chamber sides of the LC. Long-term diabetes did not change the stiffness of the DM and LC. In summary, our analyses show that the protein composition and biomechanical properties of the DM and LC are different, i.e., the LC is softer than DM despite a significantly higher concentration of collagen IV family members. This finding is unexpected, as collagen IV members are presumed to be responsible for BM stiffness. Diabetes had no significant effect on the protein composition and the biomechanical properties of both the DM and LC.

Effects of the Glaucoma Drugs Latanoprost and Brimonidine on Corneal Temperature.

PURPOSE: The aim of this study was to investigate the effects of the glaucoma drugs latanoprost, brimonidine, and the combination of both on the central corneal temperature (CT) of healthy subjects by means of infrared thermography. Changes of the central CT may reflect changes of ocular blood flow. METHODS: Before application and during 2 hours after the application of latanoprost, brimonidine, or the combination of both in one eye, the CT in both eyes of 40 healthy subjects was measured repeatedly. RESULTS: Brimonidine reduced CT by approximately 0.5°C. This effect was statistically significant (P < 0.0001). Latanoprost, however, had a very small and insignificant influence (P = 0.47). Accordingly, the combination of brimonidine and latanoprost also reduced CT up to 0.5°C, and this effect was statistically significant (P < 0.0001). CONCLUSIONS: Brimonidine, but not latanoprost, had a significant effect on central CT. This cooling effect of brimonidine is most probably due to a drug-induced reduction of blood circulation in the ciliary body and iris and to a certain extent also to a reduction of blood flow in the fundus of the eye. TRANSLATIONAL RELEVANCE: This study shows evidence that thermography of the cornea provides indirect information on the influence of drugs on the blood flow to the anterior segment of the patient's eye.

In glaucoma patients, low blood pressure is accompanied by vascular dysregulation.

BACKGROUND: There are many risk factors contributing to glaucomatous optic neuropathy. Beside increased intraocular pressure, vascular factors play a prominent role, particularly low blood pressure (BP), and vascular dysregulation. Both of them are essential components of the Flammer syndrome. The aim of this retrospective study was to evaluate whether in glaucoma patients there is a relationship between vascular dysregulation and the BP. METHODS: Medical records of 57 unselected glaucoma patients were retrospectively studied. RESULTS: Based on the outcome of the capillaroscopy, patients were divided in a group of patients with vascular dysregulation, also called long-stoppers (flow cessation for 13 s or more), and a group of patients with normal vascular regulation, also called short-stoppers (flow cessation for 12 s or less). BP was significantly lower in the group of long-stoppers than in the group of short-stoppers. This applies for both systolic (p = 0.028) and diastolic BP (p = 0.036). The regression analysis revealed also a significant inverse relationship between the duration of blood flow cessation and the systolic (p = 0.025) and diastolic BP (p = 0.016). After adjustment for age, gender, use of antihypertensive therapy, and excluding patients taking calcium channel blockers, the relationship was still significant for systolic (p = 0.025) and diastolic BP (p = 0.003). CONCLUSIONS: In glaucoma patients, vascular dysregulation (as defined by response in the nailfold capillaroscopy to a cold provocation) and low BP are statistically related. This is in line with the observation that Flammer syndrome subjects have both primary vascular dysregulation and low BP and that Flammer syndrome is a risk factor for glaucomatous optic neuropathy, at least in normal tension glaucoma patients. The detection of vascular factors in glaucoma patients may lead to a more efficient treatment, better tailored to the individual patient.

Multiple sclerosis and primary vascular dysregulation (Flammer syndrome).

BACKGROUND: Multiple sclerosis (MS) is an inflammatory demyelinating disease of the CNS of still unknown aetiology. Flammer syndrome (FS) encompasses a set of symptoms and signs that are primarily but not solely related to the dysregulation of blood vessels. The purpose of the present study was to determine whether FS symptoms occur more often in MS patients than in controls. METHODS: Fifty-eight MS patients and 259 controls answered a questionnaire covering 15 symptoms and signs of FS. RESULTS: Six of the 15 symptoms and signs of FS (dizziness, low body mass index, cold hands and/or feet, tendency toward perfectionism, reduced thirst, feeling cold) were found significantly more often in MS patients than in controls. Seven additional symptoms and signs (tinnitus, headaches, increased pain sensation, long sleep-onset time, migraines, increased response to certain drugs, low blood pressure) also occurred more often in MS patients, but the difference in frequency was not statistically significant. One sign (reversible skin blotches) was found less often in MS patients, but the difference in frequency was not statistically significant. One symptom (increased smell perception) was found significantly less often in MS patients. CONCLUSIONS: MS patients suffer significantly more often from FS symptoms and signs than controls. The reason for this association between MS and FS and the potential implications of this association still need to be determined.

Refractoriness to the effect of endothelin-1 in porcine ciliary arteries.

PURPOSE: Endothelin-1 (ET) is an important molecule in vascular physiology. After an acute stimulation with ET, vessels are to some extent temporarily refractory to further stimulation. However, few details are known about this phenomenon. The aim of our study was to verify the existence of refractoriness in ophthalmic ciliary arteries and, if present, to analyze its time course. METHODS: Twenty freshly isolated porcine ciliary arteries were placed in a myograph system to measure isometric forces. Each vessel was stimulated with 10(-7) M ET twice. The experiment was performed in 5 groups of vessels, which differed in the time interval between the initial and the second stimulation with ET. The intervals were 15 min, 30 min, 1 h, 2 h, and 4 h, respectively. RESULTS: The vasoconstrictive response to re-exposure to ET was time-dependently reduced. The response was lowest after 15 min (22% of baseline response), and then the sensitivity slowly recovered and was finally normal again after 4 h. CONCLUSIONS: Our experiment with isolated porcine ophthalmic ciliary arteries revealed a refractoriness phase to ET after an acute stimulation with ET. This refractoriness was transient and disappeared after 4 h. The lowest response was observed in the group of vessels re-exposed 15 min after the first stimulation.

[The deaf patient--information for a barrier-free conversation with patients in dentistry]. / Der gehörlose Patient--Informationen für ein barrierefreies Patientengespräch in der Zahnarztpraxis. Empfehlungen für die Kommunikation mit gehörlosen und högeschädigten Patienten in der Zahnarztpraxis.

There are about 650,000 people with hearing problems in Switzerland, 10,000 of whom use sign language. About 100,000 people are hard of hearing. Deaf patients require special treatment in the dental office as they have specific communication needs. This community, like many other minority groups, has a sign language and a culture of its own. To prevent misunderstandings it is therefore very important to provide solutions for an enhanced communication. However, guidelines for the communication with deaf dental patients are still missing. Successful communication between deaf patients and dentist is essential for effective care. This paper is concerned with providing background information and introducing recommendations for unrestricted dentist-patient communication. The aim of this article is to improve dentists' knowledge of the appropriate communication with this patient group.