Caliber Of Arterioles Research Articles

Serum and Macular Carotenoids in Relation to Retinal Vessel Caliber Fifteen Years Later, in the Second Carotenoids in Age-Related Eye Disease Study.

PurposeWe investigated whether dietary carotenoids lutein and zeaxanthin (L/Z) in the serum and macula were associated with central retinal arteriole and venule calibers in a follow-up ancillary study among older women in the Women's Health Initiative.MethodsAmong 390 women who participated in Carotenoids in Age-Related Eye Disease Study 2 (CAREDS2) (2016–2019), we investigated associations between serum L/Z at Women's Health Initiative baseline (1994–1998), and macular pigment optical density (MPOD) at CAREDS baseline (2001–2004), with central retinal vessel caliber in CAREDS2. MPOD was measured using heterochromatic flicker photometry (0.5° from the foveal center) in CAREDS baseline and CAREDS2. Vessel calibers were measured from fundus photographs (CAREDS2). We also explored associations in women with stable MPOD (±0.10 optical density units) over 15 years (n = 106), given the long-term increases in MPOD related to diet patterns and supplement use. Associations were investigated using linear modeling.ResultsIn the full sample (n = 390), higher serum L/Z (tertile 3 vs. 1) was positively associated with arteriole caliber (mean ± SE, 145.0 ± 1.4 µm vs. 140.8 ± 1.4 µm; P = 0.05) and venule caliber (214.6 ± 2.2 µm vs. 207.5 ± 2.2 µm; P = 0.03). MPOD was also associated with wider vessel calibers (tertile 3 vs. 1), but the trend was only statistically significant for venules (144.4 ± 1.4 µm vs. 141.1 ± 1.4 µm [P = 0.12] and 213.3 ± 2.1 µm vs. 206.0 ± 2.1 µm [P = 0.02], respectively.) Most associations were strengthened in women with stable MPOD over 15 years, including between MPOD and arteriole caliber (149.8 ± 2.6 µm vs.135.8 ± 3.0 µm; P = 0.001).ConclusionsHigher L/Z status in serum and retina was associated with larger central retinal vessel calibers. Prospective studies and clinical trials are needed to elucidate whether L/Z supplementation prevents vision loss through increasing blood flow.

FEATURES OF CAPILLARY BLOOD FLOW IN PATIENTS WITH PATHOLOGY OF INTRANASAL STRUCTURES AND NASAL BREATHING DISORDERS

The investigation of the vascular microcirculation system is important for diagnosis, assessment of the severity and nature of pathological processes in human body, monitoring the effectiveness of treatment. Monitoring the state of microcirculation in impaired respiratory function of the nose helps to study the subtle mechanisms of regulation of vascular−tissue relations. To do this, there were used the biomicroscopic methods to study capillary blood flow, one of the most relevant and promising is optical capillaroscopy of the nail bed. This method makes it possible to identify at the evidence level the peculiarities of the functioning of the peripheral circulatory system by the state of the capillary system and to evaluate the effectiveness of treatment by the rheological properties of blood in hematological practice. There were examined 145 patients by means of computer capillaroscopy to study the rate of capillary circulation in the patients with pathology of intranasal structures and nasal breathing disorders. All patients underwent a complete clinical examination, routine instrumental examinations, and computer capillaroscopy using a video capillaroscope with a visual magnification of up to 550 times. The obtained images were stored and processed according to a special software. During the characterization of the capillaroscopic picture there were evaluated: pathological tortuosity, change in the caliber of arterioles and venules, disorganization of the capillary network, the number of functioning capillaries. Changes in the speed and nature of capillary blood flow (accelerated, slow, stasis) were observed. The optical capillaroscopy method allows not only to visually assess the condition of microvessels, but also to determine such an important parameter as blood circulation, actually, it can replace the study of laser Doppler. Such data will be important in the diagnosis of respiratory and olfactory disorders and the formation of adequate tactics for their treatment. Key words: microcirculation, microcirculatory tract, capillary circulation, nasal obstruction, nasal breathing disorders, pathology of intranasal structures, computer capillaroscopy.

Microvascular narrowing and BP monitoring: A single centre observational study.

IntroductionHalf of all hypertensive individuals have inadequately-controlled BP because monitoring methods are ineffective. This single centre study examined consecutive subjects undergoing 24 hour BP measurements for clinic and ambulatory BP levels, and for end-organ damage (retinal microvascular abnormalities and left ventricular hypertrophy, LVH, > 1.1 cm). Retinal images were graded for microvascular retinopathy (Wong and Mitchell classification), and vessel calibre using a semiautomated method. Features were compared using chi-squared, Fisher’s exact or the student’s t test.MethodsOne hundred and thirty-one individuals (59 male, 45.0%, mean age 61.7 ± 14.5 years) were studied. Ninety-nine (76.2%) had a clinic BP ≥ 140/90 mm Hg, 84 (64.6%) had a mean awake systolic BP ≥ 135 mm Hg, 100 (76.9%) had a mean sleeping systolic BP ≥ 120 mm Hg, and 100 (76.2%) had abnormal nocturnal BP dipping patterns. Sixty-nine individuals had undergone echocardiography and 23 (33.3%) had LVH.ResultsAll participants had a mild (88.5%) or moderate (11.5%) microvascular retinopathy. Moderate microvascular retinopathy was found in 86.7% of those with a mean awake systolic BP ≥135 mm Hg (p = 0.058) but was not associated with other abnormal BP measurements, abnormal dipping patterns or LVH. However retinal arteriole calibre was reduced in subjects with a mean 24 hour awake systolic BP ≥ 135 mm Hg (p = 0.05). Retinal arteriole calibre was smaller in subjects with LVH (128.1 ± 13.5 μm compared with 137.6 ± 14.1 μm in normals, p = 0.014). Venular calibre was also less in subjects with LVH (185.4 ± 24.6 μm compared with 203.0 ± 27.2 μm in normals, p = 0.016). Arteriole narrowing predicted an increased risk of LVH (AUC 0.69, 95%CI 0.55 to 0.83) that was comparable with 24 hour systolic BP ≥130 mm Hg (AUC 0.68, 95%CI 0.53 to 0.82) and mean awake systolic BP ≥135 mm Hg (AUC 0.68, 95%CI 0.54 to 0.83).ConclusionsThis study suggests that retinal arteriole narrowing may be equally accurate in predicting LVH as any clinic or ambulatory BP measurement. The convenience and accuracy of microvascular calibre measurement mean that it should be investigated further for a role in routine hypertension assessment and monitoring.

Small vessel disease and intracoronary plaque composition: a single centre cross-sectional observational study

Cardiac events are commonly triggered by rupture of intracoronary plaque. Many studies have suggested that retinal small vessel abnormalities predict cardiac events. The present study examined retinal microvascular abnormalities associated with intracoronary plaque. This was a single centre cross-sectional observational study of consecutive subjects who underwent coronary angiography and intracoronary optical coherence tomography (OCT) of occlusive coronary artery disease. Subjects’ retinal images were deidentified and graded for microvascular retinopathy (Wong and Mitchell classification), and vessel calibre using a semiautomated method based on Knudtson’s modification of the Parr Hubbard formula. Control subjects had no significant plaque on angiography. Analysis used the Fisher’s exact test or student t-test. Thirty-two subjects with intracoronary plaque including 22 males (79%) had a mean age of 62.6 ± 9.4 years. Twenty-four (86%) had hypertension, 10 (36%) had diabetes, and 21 (75%) were current or former smokers. Their average mean arterial pressure was 90.5 ± 5.8 mm Hg, and mean eGFR was 74 ± 15/min/1.73 m2. On angiography, 23 (82%) had a left anterior descending artery (LAD) stenosis, their mean diseased vessel score was 1.86 ± 1.21, and mean total stent number was 1.04 ± 1.00. Plaque type was mainly (>50%) fibrous (n = 7), lipid (n = 7), calcific (n = 10), or mixed (n = 4). Control subjects had a lower mean diastolic BP (p = 0.01), were less likely to have an LAD stenosis (p < 0.001), a lower mean diseased vessel score (p < 0.001) and fewer stents (p = 0.02). Subjects with plaque were more likely to have a moderate microvascular retinopathy than those with none (p = 0.004). Moderate retinopathy was more common with lipid (p = 0.05) or calcific (p = 0.003) plaque. Individuals with calcific plaque had a larger arteriole calibre (158.4 ± 15.2 µm) than those with no plaque (143.8 ± 10.6 µm, p = 0.02), but calibre was not related to diabetes or smoking. Calibre did not correlate with plaque length, thickness or arc angle. Thus, subjects with intracoronary artery plaque are more likely to have a moderate microvascular retinopathy. Those with calcific plaque have larger retinal arterioles which is consistent with our previous finding of larger vessel calibre in triple coronary artery disease. Retinal microvascular imaging warrants further evaluation in identifying severe coronary artery disease.

Ocular Pulse Amplitude and Retinal Vessel Caliber Changes after Intravitreal Dexamethasone Implant.

Purpose:The purpose of this study is to evaluate possible changes in ocular pulse amplitude (OPA), retinal arteriole caliber (RAC), and retinal venule caliber (RVC), following the intravitreal injection of dexamethasone implants (DIs).Methods:Thirty-four eyes of 34 patients with macular edema were included. All participants received a full ophthalmologic examination at baseline. RAC and RVC were measured via optical coherence tomography; OPA and intraocular pressure (IOP) were measured via dynamic contour tonometry at baseline, month 1, and month 3. Statistical analysis was performed for before-after comparison of OPA, IOP, RAC, and RVC measurements.Results:The mean OPA (in order to baseline, month 1, month 3) was 2.8 ± 0.8, 2.9 ± 1.0, 2.9 ± 0.9. The mean IOP was 16.8 ± 2.9, 17.3 ± 2.7, 18.4 ± 2.9 mmHg. The mean RAC was 97.8 ± 9.2, 97.2 ± 9.0, 97.6 ± 9.4. The mean RVC was 124.4 ± 8.2, 124.8 ± 8.8, 123.8 ± 8.2. There were no statistically significant changes in RAC (P = 0.688), RVC (P = 0.714), OPA (P = 0.348), and IOP (P = 0.115). There was also no correlation between RAC and OPA (r = 0.12, P = 0.62) or RVC and OPA (r = 0.16, P = 0.68) at the last visit.Conclusion:The intravitreal injection of DI does not significantly affect RAC, RVC, or OPA, which indicates that the treatment does not alter overall retinal-choroidal vasculature or hemodynamics.

Do microvascular retinal changes improve cardiovascular risk estimation?

Do microvascular retinal changes improve cardiovascular risk estimation?

Retinal Venular Caliber Predicts Visual Outcome after Intravitreal Ranibizumab Injection Treatments for Neovascular AMD

To examine whether baseline retinal vascular caliber predicts visual response to intravitreal ranibizumab injections in patients with neovascular age-related macular degeneration (AMD). In this prospective cohort study, patients with neovascular AMD received three monthly intravitreal injections of ranibizumab, followed by as needed dosing up to 1 year. Retinal vascular caliber was measured from digital fundus photographs at baseline and summarized as central retinal artery equivalent (CRAE) and venular equivalent (CRVE), representing average caliber of arterioles and venules, respectively. Visual outcome at 12 months was assessed and the relation to baseline retinal vascular caliber was determined. A total of 88 eyes were analyzed at baseline. After accounting for age, sex, size of choroidal neovascularization, and number of injections, patients who deteriorated in visual acuity at 12 months had significantly larger baseline CRVE, 243.10 μm (95% confidence interval [CI], 227.01-259.19), compared with those who were stable, 214.30 μm (95% CI, 205.79-222.81) and those who improved, 215.26 μm (95% CI, 204.69-225.84; P = 0.007). Baseline CRAE did not differ significantly from eyes whose vision deteriorated, 150.12 μm (95% CI, 140.67-159.57), compared with those remaining stable, 143.64 μm (95% CI, 138.64-148.63), or gaining vision 142.92 μm (95% CI, 136.71-149.13; P = 0.69). In eyes with neovascular AMD treated with intravitreal ranibizumab, larger baseline retinal venular caliber was significantly associated with a poorer response to treatment, possibly reflecting increased disease severity.

Microvascular Dilatation after Haemodialysis Is Determined by the Volume of Fluid Removed and Fall in Mean Arterial Pressure

Background/Aims: The effects of haemodialysis on the microcirculation are poorly understood. This study examined the changes in small vessel calibre. Methods: 24 patients (including 12 males, median age 62.5 years, range 30–87) underwent digital retinal photography immediately before and after routine haemodialysis. Arteriolar and venular calibres were measured from the images by a trained grader using a highly reproducible, computer-assisted method. Results: Patients had an average 2.0 ± 0.3 litres of fluid removed with dialysis, and their mean arterial blood pressure fell by 6.8 mm Hg (CI 13.8–0.2, p = 0.06). Retinal arteriole calibre did not change (mean difference 2.3 µm, CI –1.1 to 5.7, p = 0.17) but the venules dilated (mean difference 12.7 µm, CI 7.3–18.3, p < 0.001). Calibre returned to baseline by 2 h. Venules dilated less in diabetics than non-diabetics (mean difference –6.2 µm, CI –9.6 to –2.9, p < 0.01). Retinal venular dilatation correlated positively with the volume of fluid removed per kilogramme body weight (5.9, CI 0.2–11.5, p = 0.04), and negatively with the fall in mean arterial pressure (–0.36, CI –0.72 to –0.01, p < 0.05) after adjusting for age, gender, diabetes and dyslipidaemia. Conclusion: Haemodialysis is associated with systemic venular dilatation.

E0392 Relationship between retinal vasculopathy and coronary artery disease

Background and objectiveStudies showed that atherosclerosis is a systemic disease. Parameters representing peripheral artery atherosclerosis, such as decreased ankle-brachial index (ABI), and increased carotid artery intima-media thickness (CIMT), are well...

Distribution and Associations of Retinal Vascular Caliber with Ethnicity, Gender, and Birth Parameters in Young Children

To describe the distribution of retinal vascular calibers and their associations with ethnicity, gender, and birth parameters in children. This was a school-based cross-sectional study of 768 children aged 7 to 9 years who participated in the Singapore Cohort Study of the Risk Factors for Myopia (SCORM). Participants had retinal photographs taken in 2001. Retinal vascular calibers were measured with computer-based program and summarized as average caliber of arterioles and venules in that eye. Associations of retinal vascular caliber with ethnicity, gender, and various birth factors were analyzed. In this population, the mean retinal arteriolar caliber was 156.4 microm (95% confidence interval [CI], 155.4-157.3) and venular caliber was 225.4 microm (95% CI, 224.1-226.8). The retinal arteriolar caliber was significantly narrower in Chinese (154.9 microm), compared with Malay (158.6 microm) and Indian (158.5 microm) children. Retinal venular caliber was also narrower in Chinese (223.3 microm) compared with Malay (230.8 microm) and Indian (229.0 microm) children. These differences were statistically significant, even after adjustments for age, gender, family income, parental education, body mass index, height, birth weight, axial length, and spherical equivalent (P = 0.05 for arteriolar caliber; P = 0.002 for venular caliber). In multivariate analysis, there were no significant gender differences in retinal vascular caliber. Birth factors, including birth weight, birth length, head circumference, and gestational age, were not significantly associated with changes in either retinal arteriolar or venular caliber. The results show ethnic variation in retinal vascular caliber in Singaporean children. No association of birth parameters with retinal vascular caliber was found. Because retinal vascular caliber is related to various cardiovascular and ocular diseases, it is possible that ethnic variations in retinal vascular caliber should be taken into consideration in future studies.

Computerized measurement of retinal blood vessel calibre: description, validation and use to determine the influence of ageing and hypertension

To validate a computer-based method for measuring the calibre of retinal blood vessels, and use it to determine the effects of ageing and arterial hypertension on the calibres of these vessels and on their ratio. Digital eye fundus images covering a 50 degrees field and centred on the optic disc were obtained using a 540 nm filter. The boundaries of blood vessels crossing a series of circles concentric with the optic disc were located by an image analysis program; the calibres of vessels crossing the circles perpendicularly were determined automatically, the average arteriole and average vein calibres were calculated, and the arteriovenous ratio (AVR) was calculated as the ratio of these averages. The within-operator, between-operator and within-eye reliability of this method was investigated using images of 30 or 40 eyes; the effects of ageing on average vessel calibres and AVR using both eyes of each of 120 normotensive volunteers aged 10-69 years (60 males, 60 females); and the effects of arterial hypertension using a group of 54 hypertensive patients aged 50.9 +/- 13.9 years. Within-operator, between-operator and within-eye correlation coefficients for AVR were all better than 0.95, and the corresponding coefficients of variation were all better than 3%. The results of Bland Altman approach show a very good agreement. There were no significant differences between right and left eyes or between the sexes in either the normotensive or the hypertensive group. In the normotensive group, vein calibre was almost constant (111 +/- 6 microm), but arteriole calibre and AVR fell significantly from 96 +/- 6 microm and 0.870 +/- 0.046, respectively, in the second decade of life to 85 +/- 4 microm and 0.761 +/- 0.044 in the seventh decade. Arterial hypertension was not associated with changes in vein calibre, but was associated with decreases in arteriole calibre (from 91 +/- 7 microm among normotensive individuals to 84 +/- 2 microm) and AVR (from 0.816 +/- 0.056 to 0.755 +/- 0.027). Age significantly modulated the AVR-reducing influence of hypertension (P = 0.003). The proposed method of measuring retinal blood vessel calibres is reliable and precise (especially for the AVR). In this study, its results confirmed that increasing age and arterial hypertension are both associated with reductions in retinal arteriole calibre and AVR.

Endothelin-mediated vascular tone following focal cerebral ischaemia in the cat.

The actions of Bosentan and PD155080, nonpeptide endothelin receptor antagonists, were examined in feline pial arterioles in situ following middle cerebral artery (MCA) occlusion to gain insight into the cerebrovascular influence of endogenous endothelins in focal cerebral ischaemia. Immediately following permanent MCA occlusion, all pial arterioles overlying the suprsylvian and ectosylvian gyri displayed marked dilatations, which were maintained in a population of vessel but differentiated into sustained constrictions in others. Perivascular subarachnoid microinjections of Bosentan (30 microM), PD155080 (30 microM), and artificial CSF (pH 7.2) were performed between 30 and 210 min following MCA occlusion. The perivascular microapplication of Bosentan (30 microM) and PD155080 (30 microM) around pial vessels overlying the suprasylvian and ectosylvian gyri, which are within the territory of the occluded MCA, elicited in increase in the calibre of postocclusion dilated and constricted pial arterioles. The perivascular microapplication of PD155080 (30 microM) around postocclusion constricted arterioles overlying the ectosylvian and suprasylvian gyri elicited an increase in the calibre of arterioles (69 +/- 49% from preinjection baseline; n = 8). The perivascular microapplication of Bosentan (30 microM) around postocclusion constricted arterioles overlying the ectosylvian and suprasylvian gyri also elicited an increase in the calibre of arterioles (68 +/- 60% from preinjection baseline; n = 13). In contrast, the microapplication of CSF (pH 7.2) elicited small reductions in pial arteriolar calibre of postocclusion constricted arterioles (-8 +/- 13% from preinjection baseline; n = 8). The perivascular microapplication of PD155080 (30 microM) around postocclusion dilated pial arterioles overlying the ectosylvian and suprasylvian gyri elicited an increase in the calibre of arterioles (11 +/- 10% from preinjection baseline; n = 38). The perivascular microapplication of Bosentan (30 microM) around postocclusion dilated arterioles elicited an increase in the calibre of arterioles (16 +/- 15% from preinjection baseline; n = 36). In contrast, the microapplication of CSF (pH 7.2) elicited small reductions in pial arteriolar calibre of postocclusion dilated arterioles (-9 +/- 6% from preinjection baseline; n = 44). Perivascular microapplication of Bosentan or PD155080 had minimal effect on the calibre of pial arterioles on the parasagittal gyrus (anterior cerebral artery territory), although these arterioles had also displayed sustained dilatation following MCA occlusion. These results indicate that contractile factors (whose effects can be reversed with endothelin receptor antagonists) constrict or impair dilatation of cortical resistance arterioles in an acute cerebral ischaemic episode.

Endothelin receptor mediated constriction and dilatation in feline cerebral resistance arterioles in vivo

The receptors mediating the cerebrovascular actions of endothelins have been examined in feline cerebral resistance arterioles in vivo. The adventitial microapplication of the endothelin ET A receptor antagonist BQ-123 (cyclo d-aspartate- d-tryptophan- l-leucine- d-valine- l-proline) (0.1–10 μM) per se had minimal effect on cerebral resistance arterioles examined. The adventitial microapplication of endothelin-1 (10 nM) elicited a marked vasoconstriction of cerebral resistance arterioles (−29.1 ± 1.9% from pre-injection baseline). The endothelin-1 induced vasoconstriction was attenuated, in a dose dependent manner, by the adventitial co-applicaticn of BQ-123 and endothelin-1 (estimated IC 50 0.7 μM). The adventitial microapplication of the endothelin ET B receptor agonist BQ-3020 N-acetyl[Ala 11,Ala 15]ET-1 (6–21)) (0.001–1 μM) effected a dose dependent vasodilatation (EC 50 30 nM, maximum response 25 ± 5% from pre-injection baseline). The magnitude of the vasodilatation elicited by BQ-3020 (100 nM and 1 μM) was dependent on the pre-injection calibre of the arterioles examined. The intracarotid infusion (via the lingual artery) of BQ-3020 (0.5–500 pmol/min) had no significant effect on the calibre of cerebral resistance arterioles. These results suggest that the peptide endothelin ET B receptor agonist fails to gain access to the cerebrovascular endothelin ET B receptors following its intraluminal administration. These investigations indicate that endothelin ET A receptors mediate vasoconstriction and endothelin ET B receptors mediate vasodilatation in feline cerebral resistance arterioles in vivo.

L-arginine dilates rat pial arterioles by nitric oxide-dependent mechanisms and increases blood flow during focal cerebral ischaemia.

L-Arginine (> or = 30 mg kg-1, i.v.), but not D-arginine (300 mg kg-1) administered 5 min after unilateral common carotid/middle cerebral artery occlusion increased regional cerebral blood flow (rCBF) within the dorsolateral ischaemic cortex in spontaneously hypertensive rats. L-Arginine (300 mg kg-1) increased rCBF from 22 +/- 2.7 to 33 +/- 4% of baseline as measured by laser-Doppler flowmetry. This increase may explain the ability of L-arginine to reduce infarct size following focal cerebral ischaemia, as reported previously. The mechanism appears to be mediated by nitric oxide since topical L-NAME (1 microM), a nitric oxide synthase inhibitor, decreased pial arteriole calibre from 115 +/- 2.2 to 106 +/- 0.9% of baseline following L-arginine infusion (300 mg kg-1).

A clinical triad to diagnose paraneoplastic retinopathy

Two elderly men developed photosensitivity and light-induced glare, transient visual symptoms, and progressive visual loss several months before small cell carcinoma of the lung was discovered. Both patients had impaired visual acuity and color vision, ring scotomas, and attenuated retinal arteriole caliber. Electroretinography demonstrated abnormal cone and rod-mediated responses. Antiretinal antibodies were identified in their serum. Their visual sensory function improved following therapy with immunosuppressive agents. The triad of photosensitivity, ring scotomatous visual field loss, and attenuated retinal arteriole caliber should alert one to a paraneoplastic disorder affecting the retina.

Gefäßkalibermessungen bei diabetischer Retinopathie vor und nach Photokoagulation

The calibers of 4 retinal arterioles and 4 venoles of each of 58 patients with diabetic retinopathy (DR) were measured on fundus photographs before and after photocoagulation (PC). The measurements were repeated at approximately one-year intervals following photocoagulation (PC) of one eye of each patient. The mean caliber of arterioles and venoles of DR patients was 15.4% greater than in nondiabetic subjects. This finding may be interpreted as an autoregulatory response to relative tissue hypoxia. Following PC there was a significant reduction in both arterial and venous vessel caliber. In a multivariate regression analysis, the reduction in venous caliber correlated significantly with the number of coagulation spots. A weak correlation was found with arterial hypertension, change in visual acuity, and change in a calculated DR score. The reduction in pathologic vessel calibers following PC is indicative of an improvement in retinal hemodynamics. Photographic quantification of retinal vessel changes may be of prognostic value, i.e., for assessing the course of DR before and after treatment by PC.

Observations on the microcirculation in the gingiva of hamsters and other laboratory animals.

By using the teeth for immobilisation and employing incident light microscopy at magnifications up to 240x, entire capillary beds could be observed in the labial gingiva in small laboratory animals. In the mandibular incisor region, simple capillary loops, as found in the human gingiva and nail bed, were absent in all species examined except in some guinea pigs. In the hamster, where the topography of the gingival capillary bed was studied in greatest detail, blood flow was regulated by changes in caliber of arterioles; by opening and closing of exits from main capillary channels into networks apparently devoid of vasomotor activity; and by opening and closing of arteriovenous anastomoses. Under certain conditions, settling of blood cells and blood cell clumps to the lower side of gingival veins, together with gravitationally layered flow, was observed.

THE CHANGE IN CAPILLARIES CAUSED BY EXPERIMENTAL OTITIS MEDIA

By injection of staphylococcus aureus or 3% silver nitrate solution into the tympanic cavities through the ear drum, otitis media was induced in 48 rabbits. Changes of size of capillary nets and caribres. of capillaries were observed in the rabbit's ear suffered from otitis media for 24 hours to 130 days.The conclusions summarized were as follows:1) In the staphylococcus group, the capillaries in the mucous membrane of the tympanic cavity revealed a remarkable change. In the silver nitrate group, the flow of India ink to the capillaries was hardly recognized, and major area of the, tympanic cavity was in the state of necrosis.2) The capillaries of the tympanic cavity wall rapidly increased in number in early stage (5_??_20 days) of middle ear inflammation, and remained increased even in later stage (1_??_4 months).3) New vessels grown from conical germ were extremely fine. India ink did not extravasate through the vessel wall.4) The calibre of new vessels gradually grew larger and finally became as large as that of ordinary capillary network. By this time swelling of germ diminished or disappeared.5) The calibre of venules grew larger rapidly and remarkably since very early stage (2 days). In some animals, they grew about twice as large.6) The calibre of arterioles also grew larger in early stage, but was not so remarkable as venules.7) The calibre of arterioles and venules in 1_??_4 months had tendencies that their rate of dilatation became lower than those in early stage.8) The net capillaries were slow-in dilatation compared with that of arterioles and venules, and the rate of dilatation was lower than that of arterioles. In 3_??_4 months, there were tendencies that the rate of dilatation became higher.9) During the course of this experiment, no remarkable change of new vessels and the calibre was revealed in the bony substance.10) The leakage of India ink was remarkable in the venous side of capillaries, suggesting the increase of permeability or haemorrhagia per diapedesin in these areas.11) In the staphylococcus group, the growth of granulation tissue from the tympanic cavity wall was observed in almost all cases in 7_??_130 days. The granulation tissue was observed mostly on the surface of the malleus, the stapes, the incus, the round window and the drum, in order of their frequency. In the silver nitrate group, the granulation tissue was observed in all cases in 10_??_50 days.12) There were two types of growth of the blood vessels in the granulation tissue-one grown from germ, and another from fibroblasts around the area of bleeding.13) In the staphylococcus group, in 5 cases out of 23, and in the silver nitrate group, in 7 cases out of 8, remarkable dilatation of capillaries in the stria vascularis was observed, mostly in early stage of middle ear inflammation.14) In the inner ear, a remarkable dilatation of venules was also shown.15) Net capillaries in the sria vascularis showed the remarkable dilataion compared with those in the middle ear. Dilatation was also remarkable in the crista acustica.16) Spread of inflammation to the inner ear was mostly through the round window. Dilatation of the inner ear vessels in early stage was probably due to inflammatory products permeating through the round window vessels.17) In the staphylococcus group, in 4 cases out of 23, the growth of secondary cholesteatomain the auditory canal were observed (in one case, cholesteatoma invaded into the tympanic cavity).The capillaries surrounding cholesteatoma were dilated forming dense network.