Decreased Choroidal Blood Perfusion Induces Myopia in Guinea Pigs

The capillary bed has been observed in the Achilles tendon of 40 bullfrogs and 10 guinea pigs for periods of up to 2 h. The opening and closing of adjacent capillaries in a perfused area follows the pattern originally described by Krogh for skeletal muscle but the frequency is slower, as anticipated from the lower metabolic rate of tendon. However, superimposed on this "flickering is a much slower process whereby whole bundles of 20–147 capillaries open and close with little overlap in the tissue areas perfused by each. Periods of no flow averaged 39 min in 70 bundles followed in bullfrogs and 43 min in 34 bundles followed in guinea pigs, although a few failed to open in 100 min. This bundle phenomenon is discussed in relation to the serious implications in mathematically modeling the exchange of gases and nutrients between blood and tissue and the possible errors in assuming time averaging when determining blood perfusion rates. Also mentioned are the likely effects of decompression on closed bundles and the notion is introduced that the bundle phenomenon may be a factor determining which tissues can be injured by decompression.

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Increased Choroidal Blood Perfusion Can Inhibit Form Deprivation Myopia in Guinea Pigs

Investigative Opthalmology & Visual Science ◽

10.1167/iovs.61.13.25 ◽

2020 ◽

Vol 61 (13) ◽

pp. 25 ◽

Cited By ~ 2

Author(s):

Xuan Zhou ◽

Sen Zhang ◽

Guoyun Zhang ◽

Yizhong Chen ◽

Yi Lei ◽

...

Keyword(s):

Guinea Pigs ◽

Blood Perfusion

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Dietary ω-3 polyunsaturated fatty acids are protective for myopia

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2104689118 ◽

2021 ◽

Vol 118 (43) ◽

pp. e2104689118

Author(s):

Miaozhen Pan ◽

Fei Zhao ◽

Bintao Xie ◽

Hao Wu ◽

Sen Zhang ◽

...

Keyword(s):

Fatty Acids ◽

Polyunsaturated Fatty Acids ◽

Guinea Pigs ◽

Human Subjects ◽

Blood Perfusion ◽

Omega 3 ◽

Myopia Progression ◽

Control And Prevention ◽

Near Work ◽

Myopia Control

Myopia is a leading cause of visual impairment and blindness worldwide. However, a safe and accessible approach for myopia control and prevention is currently unavailable. Here, we investigated the therapeutic effect of dietary supplements of omega-3 polyunsaturated fatty acids (ω-3 PUFAs) on myopia progression in animal models and on decreases in choroidal blood perfusion (ChBP) caused by near work, a risk factor for myopia in young adults. We demonstrated that daily gavage of ω-3 PUFAs (300 mg docosahexaenoic acid [DHA] plus 60 mg eicosapentaenoic acid [EPA]) significantly attenuated the development of form deprivation myopia in guinea pigs and mice, as well as of lens-induced myopia in guinea pigs. Peribulbar injections of DHA also inhibited myopia progression in form-deprived guinea pigs. The suppression of myopia in guinea pigs was accompanied by inhibition of the “ChBP reduction–scleral hypoxia cascade.” Additionally, treatment with DHA or EPA antagonized hypoxia-induced myofibroblast transdifferentiation in cultured human scleral fibroblasts. In human subjects, oral administration of ω-3 PUFAs partially alleviated the near-work–induced decreases in ChBP. Therefore, evidence from these animal and human studies suggests ω-3 PUFAs are potential and readily available candidates for myopia control.

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Rate of Gas Exchange in the Middle Ear of Guinea Pigs

Annals of Otology Rhinology & Laryngology ◽

10.1177/000348949810700302 ◽

1998 ◽

Vol 107 (3) ◽

pp. 194-198 ◽

Cited By ~ 12

Author(s):

Haya Mover-Lev ◽

Jacob Sadé ◽

Amos Ar

Keyword(s):

Gas Exchange ◽

Middle Ear ◽

Guinea Pigs ◽

Blood Perfusion ◽

Limiting Factors ◽

Physiological Mechanisms ◽

Diffusion Limited ◽

Carbon Dioxide Co2 ◽

Rate Ratios ◽

Limited Process

Gas exchange between blood in the middle ear (ME) mucosa and ambient ME gas may be limited by diffusion through tissue or blood perfusion. In order to study the limiting factors in ME gas exchange, a hole was drilled in the bulla of 14 anesthetized guinea pigs through which a mass spectrometer probe was inserted and sealed in place. The rate at which oxygen (O2), carbon dioxide (CO2), nitrogen, and argon concentrations changed toward their steady state values was recorded. From the exponential fitted curves, gas rate constants (Kg) were calculated. The ratio KCO2/KO2 was 4:1, which is lower than expected from a diffusion-limited process in an aqueous compartment. The different rate ratios of CO2 and O2 indicate a diffusion-limited process. However, the deviation of the KCO2/KO2 ratio from that expected in aqueous solutions may indicate the involvement of a lipid compartment in gas exchange or other physiological mechanisms such as local acidity.

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Blood Flow in Expanded Tissue Treated with an Anticontractile Agent

Annals of Otology Rhinology & Laryngology ◽

10.1177/000348949110001202 ◽

1991 ◽

Vol 100 (12) ◽

pp. 962-965 ◽

Cited By ~ 1

Author(s):

John W. Canady ◽

Kevin M. Kelly ◽

Christopher A. Squier ◽

Janusz Bardach

Keyword(s):

Blood Flow ◽

Guinea Pigs ◽

Laser Doppler Velocimetry ◽

Tissue Expansion ◽

Blood Perfusion ◽

Doppler Velocimetry ◽

Expansion Process ◽

Ischemic Complications ◽

Group 2 ◽

Group 1

The present study investigates blood flow at several stages of expansion with and without enhancement by anticontractile agents (papaverine). Twelve 1-kg guinea pigs were divided into two groups. In group 1 were six animals undergoing tissue expansion without anticontractile agents, and in group 2 were six animals treated with a saturated solution of papaverine prior to expansion. Laser-Doppler velocimetry was used to monitor the changes in blood perfusion that occurred with each expansion. Animals pretreated with papaverine (group 2) maintained higher blood flow following inflation of the expander than untreated animals (group 1). This study provides physiologic evidence of the benefits of pharmacologic enhancement of the expansion process. Agents of this type may have a future role in the prevention of ischemic complications.

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Investigation of the relaxant effects of propofol on ovalbumin-induced asthma in guinea pigs

European Journal of Anaesthesiology ◽

10.1017/s0265021506000415 ◽

2006 ◽

pp. 1

Author(s):

I. Bagcivan ◽

O. Cevit ◽

M. K. Yildirim ◽

S. Gursoy ◽

S. Yildirim ◽

...

Keyword(s):

Guinea Pigs

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Hepatocyte Alterations in Guinea Pigs FED Polychlorinated Biphenyls (PCBs), Dibenzodioxins (PCDD), AND DIBENZOFURANS (PCDF)

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100053085 ◽

1982 ◽

Vol 40 ◽

pp. 56-57

Author(s):

J. N. Turner ◽

D. N. Collins

Keyword(s):

Guinea Pigs ◽

Room Temperature ◽

Dose Group ◽

Methyl Cellulose ◽

Uranyl Acetate ◽

Target Organ ◽

Office Building ◽

Lead Citrate ◽

Control Groups ◽

Cooling Fluid

A fire involving an electric service transformer and its cooling fluid, a mixture of PCBs and chlorinated benzenes, contaminated an office building with a fine soot. Chemical analysis showed PCDDs and PCDFs including the highly toxic tetra isomers. Guinea pigs were chosen as an experimental animal to test the soot's toxicity because of their sensitivity to these compounds, and the liver was examined because it is a target organ. The soot was suspended in 0.75% methyl cellulose and administered in a single dose by gavage at levels of 1,10,100, and 500mgm soot/kgm body weight. Each dose group was composed of 6 males and 6 females. Control groups included 12 (6 male, 6 female) animals fed activated carbon in methyl cellulose, 6 males fed methyl cellulose, and 16 males and 10 females untreated. The guinea pigs were sacrificed at 42 days by suffocation in CO2. Liver samples were immediately immersed and minced in 2% gluteraldehyde in cacadylate buffer at pH 7.4 and 4°C. After overnight fixation, samples were postfixed in 1% OsO4 in cacodylate for 1 hr at room temperature, embedded in epon, sectioned and stained with uranyl acetate and lead citrate.

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Glycogen in guinea pig neutrophils: Ultrastructural study of neutrophils at the intradermal site of BCG injection

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100077207 ◽

1983 ◽

Vol 41 ◽

pp. 726-727

Author(s):

Corazon D. Bucana

Keyword(s):

Bone Marrow ◽

Guinea Pig ◽

Electron Density ◽

Peritoneal Cavity ◽

Ultrastructural Study ◽

Guinea Pigs ◽

Random Distribution ◽

Glycogen Content ◽

Polymorphonuclear Neutrophils ◽

Ultrastructural Studies

In the circulating blood of man and guinea pigs, glycogen occurs primarily in polymorphonuclear neutrophils and platelets. The amount of glycogen in neutrophils increases with time after the cells leave the bone marrow, and the distribution of glycogen in neutrophils changes from an apparently random distribution to large clumps when these cells move out of the circulation to the site of inflammation in the peritoneal cavity. The objective of this study was to further investigate changes in glycogen content and distribution in neutrophils. I chose an intradermal site because it allows study of neutrophils at various stages of extravasation.Initially, osmium ferrocyanide and osmium ferricyanide were used to fix glycogen in the neutrophils for ultrastructural studies. My findings confirmed previous reports that showed that glycogen is well preserved by both these fixatives and that osmium ferricyanide protects glycogen from solubilization by uranyl acetate.I found that osmium ferrocyanide similarly protected glycogen. My studies showed, however, that the electron density of mitochondria and other cytoplasmic organelles was lower in samples fixed with osmium ferrocyanide than in samples fixed with osmium ferricyanide.

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Densitometric Identification of Primitive Erythroblasts After Reaction With Diaminobenzidine

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100072083 ◽

1973 ◽

Vol 31 ◽

pp. 328-329

Author(s):

John A. Trotter

Keyword(s):

Red Blood Cells ◽

Analytical Method ◽

Blood Cells ◽

Guinea Pigs ◽

Specific Protein ◽

Visual Examination ◽

Hemoglobin Synthesis ◽

Peroxidatic Activity ◽

Small Density

Hemoglobin is the specific protein of red blood cells. Those cells in which hemoglobin synthesis is initiated are the earliest cells that can presently be considered to be committed to erythropoiesis. In order to identify such early cells electron microscopically, we have made use of the peroxidatic activity of hemoglobin by reacting the marrow of erythropoietically stimulated guinea pigs with diaminobenzidine (DAB). The reaction product appeared as a diffuse and amorphous electron opacity throughout the cytoplasm of reactive cells. The detection of small density increases of such a diffuse nature required an analytical method more sensitive and reliable than the visual examination of micrographs. A procedure was therefore devised for the evaluation of micrographs (negatives) with a densitometer (Weston Photographic Analyzer).

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Annulate lamellae in the Sertoli cells of guinea pig testis after unilateral torsion of the spermatic cord

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100111094 ◽

1984 ◽

Vol 42 ◽

pp. 196-197

Author(s):

J. Chakraborty ◽

A. P. Sinha Hikim ◽

J. S. Jhunjhunwala

Keyword(s):

Sertoli Cells ◽

Guinea Pigs ◽

Spermatic Cord ◽

Present Report ◽

Cell Types ◽

Annulate Lamellae ◽

Spermatogenic Cells ◽

Electron Microscopic ◽

Structural Details ◽

First Time

Although the presence of annulate lamellae was noted in many cell types, including the rat spermatogenic cells, this structure was never reported in the Sertoli cells of any rodent species. The present report is based on a part of our project on the effect of torsion of the spermatic cord to the contralateral testis. This paper describes for the first time, the fine structural details of the annulate lamellae in the Sertoli cells of damaged testis from guinea pigs.One side of the spermatic cord of each of six Hartly strain adult guinea pigs was surgically twisted (540°) under pentobarbital anesthesia (1). Four months after induction of torsion, animals were sacrificed, testes were excised and processed for the light and electron microscopic investigations. In the damaged testis, the majority of seminiferous tubule contained a layer of Sertoli cells with occasional spermatogonia (Fig. 1). Nuclei of these Sertoli cells were highly pleomorphic and contained small chromatinic clumps adjacent to the inner aspect of the nuclear envelope (Fig. 2).

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