Biomedical subjects

H Cheng

Publications and source records attributed to H Cheng.

At least 181 records · Page 10Linked to original sources

PubMed1999

[Effects of immobilization on the mechanical properties of rabbit patellar tendon].

The aim of this study was to evaluate the effect of immobilization on the mechanical properties of rabbit patellar tendon(PT). IN this study, the rabbit knee was immobilized in extension for 6 weeks, then the mechanical properteis of PT were investigated. The results showed that the stress-strain relationship of PT could be expressed with exponential functions, and there were significant differeces between the normal group and the immobilized group in their theoretical curves of stress-strain relationship and two material constants of PT. Also, significant differences were found in tensile strength and tangent modulus between the two groups, but the maximum load of PT in the immobilized group did not decrease significantly. On the basis of the findings listed above, it is believed that PT would remodel and change its mechanical properties in response to the changes of mechanical stress exerted on it when the knee is immobilized.

Animals↗

PubMed1998

Termination of Ca2+ release by a local inactivation of ryanodine receptors in cardiac myocytes.

In heart, a robust regulatory mechanism is required to counteract the regenerative Ca2+-induced Ca2+ release from the sarcoplasmic reticulum. Several mechanisms, including inactivation, adaptation, and stochastic closing of ryanodine receptors (RyRs) have been proposed, but no conclusive evidence has yet been provided. We probed the termination process of Ca2+ release by using a technique of imaging local Ca2+ release, or "Ca2+ spikes", at subcellular sites; and we tracked the kinetics of Ca2+ release triggered by L-type Ca2+ channels. At 0 mV, Ca2+ release occurred and terminated within 40 ms after the onset of clamp pulses (0 mV). Increasing the open-duration and promoting the reopenings of Ca2+ channels with the Ca2+ channel agonist, FPL64176, did not prolong or trigger secondary Ca2+ spikes, even though two-thirds of the sarcoplasmic reticulum Ca2+ remained available for release. Latency of Ca2+ spikes coincided with the first openings but not with the reopenings of L-type Ca2+ channels. After an initial maximal release, even a multi-fold increase in unitary Ca2+ current induced by a hyperpolarization to -120 mV failed to trigger additional release, indicating absolute refractoriness of RyRs. When the release was submaximal (e.g., at +30 mV), tail currents did activate additional Ca2+ spikes; confocal images revealed that they originated from RyRs unfired during depolarization. These results indicate that Ca2+ release is terminated primarily by a highly localized, use-dependent inactivation of RyRs but not by the stochastic closing or adaptation of RyRs in intact ventricular myocytes.

Animals↗

PubMed1998

Direct measurement of SR release flux by tracking 'Ca2+ spikes' in rat cardiac myocytes.

1. Ca2+ release flux across the sarcoplasmic reticulum (SR) during cardiac excitation-contraction coupling was investigated using a novel fluorescence method. Under whole-cell voltage-clamp conditions, rat ventricular myocytes were dialysed with a high concentration of EGTA (4.0 mM, 150 nM free Ca2+), to minimize the residence time of released Ca2+ in the cytoplasm, and a low-affinity, fast Ca2+ indicator, Oregon Green 488 BAPTA-5N (OG-5N; 1.0 mM, Kd approximately 31 microM), to optimize the detection of localized high [Ca2+] in release site microdomains. Confocal microscopy was employed to resolve intracellular [Ca2+] at high spatial and temporal resolution. 2. Analytical and numerical analyses indicated that, under conditions of high EGTA concentration, the free [Ca2+] change is the sum of two terms: one major term proportional to the SR release flux/Ca2+ influx, and the other reflecting the running integral of the released Ca2+. 3. Indeed, the OG-5N transients in EGTA-containing cells consisted of a prominent spike followed by a small pedestal. The OG-5N spike closely resembled the first derivative (d[Ca2+]/dt) of the conventional Ca2+ transient (with no EGTA), and mimicked the model-derived SR Ca2+ release function reported previously. In SR Ca2+-depleted cells, the OG-5N transient also closely followed the waveform of L-type Ca2+ current (ICa). Using ICa as a known source of Ca2+ influx, SR flux can be calibrated in vivo by a linear extrapolation of the ICa-elicited OG-5N signal. 4. The OG-5N image signal was localized to discrete release sites at the Z-line level of sarcomeres, indicating that the local OG-5N spike arises from 'Ca2+ spikes' at transverse (T) tubule-SR junctions (due to the imbalance between calcium ions entering the cytosol and the buffer molecules). 5. Both peak SR release flux and total amount of released Ca2+ exhibited a bell-shaped voltage dependence. The temporal pattern of SR release also varied with membrane voltage: Ca2+ release was most synchronized and produced maximal peak release flux (4.2 mM s-1) at 0 mV; in contrast, maximal total release occurred at -20 mV (71 versus 61 microM at 0 mV), but the localized release signals were partially asynchronous. Since the maximal conventional [Ca2+] transient and contraction were elicited at 0 mV, it appears that not only the amount of Ca2+ released, but also the synchronization among release sites affects the whole-cell Ca2+ transient and the Ca2+-myofilament interaction.

Algorithms↗

PubMed1998

Transcription factor MSY-1 regulates expression of the murine growth hormone receptor gene.

Previous studies identified and partially characterized a 42-base pair regulatory element in the 5'-flanking region of the L1 transcript of the murine growth hormone (GH) receptor gene that interacted with both double- and single-stranded DNA-binding proteins. We present evidence that the double-stranded DNA-binding protein is NF-Y, a CCAAT box-binding protein. Experiments with a dominant negative form of NF-Y indicate that NF-Y does not play a direct role in regulating the activity of the FP42 element. A cDNA clone that specifically interacts with the upper (coding) strand of the regulatory element was isolated by screening a cDNA expression library using the Southwestern technique. DNA sequencing, electrophoretic mobility shift assay, Southwestern blot analysis, and supershift EMSA confirm the identity of the single-stranded binding protein to be MSY-1, a DNA-binding protein that is evolutionary conserved from prokaryotes to eukaryotes. Mapping of single-stranded DNA configurations reveals that MSY-1 can facilitate the formation of single-stranded DNA regions in the GH receptor 5'-flanking region. Transient transfection experiments support the role of MSY-1 as a repressor of GH receptor gene activation. Southwestern blot analysis indicates that the levels of nuclear MSY-1 are decreased in the livers of pregnant mice, suggesting a role for MSY-1 in the increased expression of the GH receptor during pregnancy.

Animals↗

PubMed1998

An electrochemical, kinetic, and spectroscopic characterization of [2Fe-2S] vegetative and heterocyst ferredoxins from Anabaena 7120 with mutations in the cluster binding loop.

Residues within the cluster binding loops of plant-type [2Fe-2S] ferredoxins are highly conserved and serve to structurally stabilize this unique region of the protein. We have investigated the influence of these residues on the thermodynamic reduction potentials and rate constants of electron transfer to ferredoxin:NADP+ reductase (FNR) by characterizing various single and multiple site-specific mutants of both the vegetative (VFd) and the heterocyst (HFd) [2Fe-2S] ferredoxins from Anabaena. Incorporation of residues from one isoform into the polypeptide backbone of the other created hybrid mutants whose reduction potentials either were not significantly altered or were shifted, but did not reconcile the 33-mV potential difference between VFd and HFd. The reduction potential of VFd appears relatively insensitive to mutations in the binding loop, excepting nonconservative variations at position 78 (T78A/I) which resulted in approximately 40- to 50-mV positive shifts compared to wild type. These perturbations may be linked to the role of the T78 side chain in stabilizing an ordered water channel between the iron-sulfur cluster and the surface of the wild-type protein. While no thermodynamic barrier to electron transfer to FNR is created by these potential shifts, the electron-transfer reactivities of mutants T78A/I (as well as T48A which has a wild-type-like potential) are reduced to approximately 55-75% that of wild type. These studies suggest that residues 48 and 78 are involved in the pathway of electron transfer between VFd and FNR and/or that mutations at these positions induce a unique, but unproductive orientation of the two proteins within the protein-protein complex.

Anabaena↗

PubMed1998

Evolution of the avian sex chromosomes from an ancestral pair of autosomes.

Among the mechanisms whereby sex is determined in animals, chromosomal sex determination is found in a wide variety of distant taxa. The widespread but not ubiquitous occurrence, not even within lineages, of chromosomal sex determination suggests that sex chromosomes have evolved independently several times during animal radiation, but firm evidence for this is lacking. The most favored model for this process is gradual differentiation of ancestral pairs of autosomes. As known for mammals, sex chromosomes may have a very ancient origin, and it has even been speculated that the sex chromosomes of mammals and birds would share a common chromosomal ancestry. In this study we showed that the two genes, ATP5A1 and CHD1, so far assigned to the female-specific W chromosome of birds both exist in a very closely related copy on the Z chromosome but are not pseudoautosomal. This indicates a common ancestry of the two sex chromosomes, consistent with the evolution from a pair of autosomes. Comparative mapping demonstrates, however, that ATP5A1 and CHD1 are not sex-linked among eutherian mammals; this is also not the case for the majority of other genes so far assigned to the avian Z chromosome. Our results suggest that the evolution of sex chromosomes has occurred independently in mammals and birds.

Animals↗

PubMed1998

Deep-Sea coral evidence for rapid change in ventilation of the deep north atlantic 15,400 years Ago

Coupled radiocarbon and thorium-230 dates from benthic coral species reveal that the ventilation rate of the North Atlantic upper deep water varied greatly during the last deglaciation. Radiocarbon ages in several corals of the same age, 15.41 +/- 0.17 thousand years, and nearly the same depth, 1800 meters, in the western North Atlantic Ocean increased by as much as 670 years during the 30- to 160-year life spans of the samples. Cadmium/calcium ratios in one coral imply that the nutrient content of these deep waters also increased. Our data show that the deep ocean changed on decadal-centennial time scales during rapid changes in the surface ocean and the atmosphere.

Journal Article↗

PubMed1998

Demonstration of adhesion activity of the soluble Ig-domain protein C-CAM4 by attachment to the plasma membrane.

The carcinoembryonic antigen (CEA) family is a large group of proteins with immunoglobulin (Ig)-like structures. The membrane-associated CEA-family proteins have been shown to mediate intercellular adhesion. In addition to these membrane-associated proteins, several secreted CEA-like proteins, such as C-CAM4, PSG1b, and PSG11s, have also been identified. The functions of these soluble proteins are not clear because they cannot support intercellular adhesion like the membrane-associated proteins can. A fundamental question important for understanding the functions of these soluble proteins is whether they can interact in a homophilic fashion as do many of their membrane-associated homologues. We found that the homophilic interactions between these soluble proteins were too weak to be detected by solution binding assays. This is not unexpected because interactions between adhesion molecules are usually transient and weak to allow for control of association and dissociation. By expressing these soluble CEA-family proteins, C-CAM4, PSG1b, and PSG11s, as membrane-anchored forms, we showed that C-CAM4 could mediate intercellular adhesion, whereas PSG1b and PSG11s, despite their 52% identity to C-CAM4, could not. These results suggest that C-CAM4, but not PSG1b and PSG11s, can probably form homodimers. Thus, these secretory CEA-family members most likely have different interaction mechanisms, i.e., C-CAM4 might function as dimers, while PSGs might function as monomers.

Adenosine Triphosphatases↗

PubMed1998

Age-associated reductions in cardiac beta1- and beta2-adrenergic responses without changes in inhibitory G proteins or receptor kinases.

While an age-associated diminution in myocardial contractile response to beta-adrenergic receptor (beta-AR) stimulation has been widely demonstrated to occur in the context of increased levels of plasma catecholamines, some critical mechanisms that govern beta-AR signaling must still be examined in aged hearts. Specifically, the contribution of beta-AR subtypes (beta1 versus beta2) to the overall reduction in contractile response with aging is unknown. Additionally, whether G protein-coupled receptor kinases (GRKs), which mediate receptor desensitization, or adenylyl cyclase inhibitory G proteins (Gi) are increased with aging has not been examined. Both these inhibitory mechanisms are upregulated in chronic heart failure, a condition also associated with diminished beta-AR responsiveness and increased circulatory catecholamines. In this study, the contractile responses to both beta1-AR and beta2-AR stimulation were examined in rat ventricular myocytes of a broad age range (2, 8, and 24 mo). A marked age-associated depression in contractile response to both beta-AR subtype stimulation was observed. This was associated with a nonselective reduction in the density of both beta-AR subtypes and a reduction in membrane adenylyl cyclase response to both beta-AR subtype agonists, NaF or forskolin. However, the age-associated diminutions in contractile responses to either beta1-AR or beta2-AR stimulation were not rescued by inhibiting Gi with pertussis toxin treatment. Further, the abundance or activity of beta-adrenergic receptor kinase, GRK5, or Gi did not significantly change with aging. Thus, we conclude that the positive inotropic effects of both beta1- and beta2-AR stimulation are markedly decreased with aging in rat ventricular myocytes and this is accompanied by decreases in both beta-AR subtype densities and a reduction in membrane adenylate cyclase activity. Neither GRKs nor Gi proteins appear to contribute to the age-associated reduction in cardiac beta-AR responsiveness.

Adenylate Cyclase Toxin↗

PubMed1998

The role of aromatic and acidic amino acids in the electron transfer reaction catalyzed by spinach ferredoxin-dependent glutamate synthase.

Treatment of the ferredoxin-dependent, spinach glutamate synthase with N-bromosuccinimide (NBS) modifies 2 mol of tryptophan residues per mol of enzyme, without detectable modification of other amino acids, and inhibits enzyme activity by 85% with either reduced ferredoxin or reduced methyl viologen serving as the source of electrons. The inhibition of ferredoxin-dependent activity resulting from NBS treatment arises entirely from a decrease in the turnover number. Complex formation of glutamate synthase with ferredoxin prevented both the modification of tryptophan residues by NBS and inhibition of the enzyme. NBS treatment had no effect on the secondary structure of the enzyme, did not affect the Kms for 2-oxoglutarate and glutamine, did not affect the midpoint potentials of the enzyme's prosthetic groups and did not decrease the ability of the enzyme to bind ferredoxin. It thus appears that the ferredoxin-binding site(s) of glutamate synthase contains at least one, and possibly two, tryptophans. Replacement of either phenylalanine at position 65, in the ferredoxin from the cyanobacterium Anabaena PCC 7120, with a non-aromatic amino acid, or replacement of the glutamate at ferredoxin position 94, decreased the turnover number compared to that observed with wild-type Anabaena ferredoxin. The effect of the change at position 65 was quite modest compared to that at position 94, suggesting that an aromatic amino acid is not absolutely essential at position 65, but that glutamate 94 is essential for optimal electron transfer.

Amino Acid Oxidoreductases↗

PubMed1998

Chemokine synthesis in the HSV-1-infected cornea and its suppression by interleukin-10.

Herpes simplex virus type 1 (HSV-1) infection of the murine cornea results in a tissue-destructive inflammatory response. In this study we show that virus infection induces the synthesis of macrophage inflammatory protein-2 (MIP-2), MIP-1alpha, and monocyte chemoattractant protein-1 (MCP-1). However, only the production of MIP-2 and MIP-1alpha coincided with the influx of leukocytes into the cornea. IL-10 treatment markedly suppressed chemokine message and protein synthesis in vivo. Local administration of IL-10 also dramatically reduced the number of T cells and neutrophils migrating into the cornea and suppressed the severity of corneal disease. The inflammatory response could also be suppressed by the passive transfer of neutralizing antibody to MIP-1alpha but not MCP-1. We conclude that local IL-10 administration can suppress chemokine synthesis, thereby ameliorating corneal disease. Furthermore, our results indicate that MIP-1alpha plays a major role in herpes stromal keratitis development, whereas MCP-1 does not.

Animals↗

PubMed1998

High-resolution MRI of intact and transected rat spinal cord.

Spinal cord transection at midthoracic level leads to an immediate loss of hindlimb motor function as well as to a progressive degeneration of descending and ascending spinal cord pathways. Thoracic spinal cord in unlesioned control rats and in rats 2 to 6 months after complete midthoracic transection were imaged in vivo using an ultrahigh-field (4.7 T) magnetic resonance spectrometer. High-resolution spin-echo and inversion-recovery pulse sequences were employed. In addition, the apparent diffusion coefficients (ADCs) in longitudinal and transverse directions of the spinal cord were determined. Anatomical MRI findings were confirmed in histological spinal cord tissue preparations. In healthy spinal cord, gray and white matter were easily discerned in proton density-weighted images. An infield resolution of max. 76 micrometers per pixel was achieved. In animals with chronic spinal cord transection changes in gray-white matter structure and contrast were observed toward the cut end. The spinal cord stumps showed a tapering off. This coincided with changes in the longitudinal/transverse ADC ratio. Fluid-filled cysts were found in most cases at the distal end of the rostral stump. The gap between the stumps contained richly vascularized scar tissue. Additional pathologic changes included intramedullary microcysts, vertebral dislocations, and in one animal compression of the spinal cord. In conclusion, MRI was found to be a useful method for in vivo investigation of anatomical and physiological changes following spinal cord transection and to estimate the degree of neural degeneration. In addition, MRI allows the description of the accurate extension of fluid spaces (e.g., cysts) and of water diffusion characteristics which cannot be achieved by other means in vivo.

Animals↗

PubMed1998

Effects of early discordant binocular vision on the postnatal development of parvocellular neurons in the monkey lateral geniculate nucleus.

The effects of early discordant binocular vision on the fidelity of signal transfer in parvocellular neurons of the lateral geniculate nucleus (LGN) were investigated in rhesus monkeys reared with ocular misalignment (strabismus). Unilateral convergent strabismus (esotropia) was surgically induced in four infant monkeys between 20 and 30 days of age and the animals were reared in a normally lighted environment until they were adults. Extracellular microelectrode recordings were made in individual units of anesthetized and paralyzed subjects. Drifting sinusoidal gratings were used as visual stimuli. Within-unit comparisons of the LGN action potentials (LGN output) and S potentials (retinal input) were performed to determine the accuracy of signal transfer in the LGN. Contrary to the previous findings in the cat LGN, the signal transfer characteristics of parvocellular units in strabismic monkeys were normal regardless of stimulus spatial frequency, temporal frequency, or contrast. The differences between cats and monkeys in LGN circuitry and the relative maturity of the central visual pathway at the onset of strabismus may have contributed to the apparent species differences in the functional development of the LGN.

Action Potentials↗

PubMed1998

A simple numerical model of calcium spark formation and detection in cardiac myocytes.

The elementary events of excitation-contraction coupling in heart muscle are Ca2+ sparks, which arise from one or more ryanodine receptors in the sarcoplasmic reticulum (SR). Here a simple numerical model is constructed to explore Ca2+ spark formation, detection, and interpretation in cardiac myocytes. This model includes Ca2+ release, cytosolic diffusion, resequestration by SR Ca2+-ATPases, and the association and dissociation of Ca2+ with endogenous Ca2+-binding sites and a diffusible indicator dye (fluo-3). Simulations in a homogeneous, isotropic cytosol reproduce the brightness and the time course of a typical cardiac Ca2+ spark, but underestimate its spatial size (approximately 1.1 micron vs. approximately 2.0 micron). Back-calculating [Ca2+]i by assuming equilibrium with indicator fails to provide a good estimate of the free Ca2+ concentration even when using blur-free fluorescence data. A parameter sensitivity study reveals that the mobility, kinetics, and concentration of the indicator are essential determinants of the shape of Ca2+ sparks, whereas the stationary buffers and pumps are less influential. Using a geometrically more complex version of the model, we show that the asymmetric shape of Ca2+ sparks is better explained by anisotropic diffusion of Ca2+ ions and indicator dye rather than by subsarcomeric inhomogeneities of the Ca2+ buffer and transport system. In addition, we examine the contribution of off-center confocal sampling to the variance of spark statistics.

Aniline Compounds↗

PubMed1998

Ectopia lentis et pupillae. A hypothesis revisited.

BACKGROUND: Ectopia lentis et pupillae (ELeP) is a rare congenital inherited disorder characterized by lenticular and pupillary ectopia. Recent speculation on its pathogenesis is based on clinical observation and includes a neuroectodermal defect or persistence of fetal vasculature. None of these reports included histopathology or imaging studies. STUDY DESIGN: Case report and literature review. INTERVENTION: The authors examined a 55-year-old woman with ELeP using 10-MHz and 50-MHz ultrasonography to demonstrate the structural abnormalities present. Five patients (eight eyes) who had undergone cataract extraction without lens implantation were also examined. RESULTS: In the patient with ELeP, the right pupil was displaced inferiorly and the left temporally. An ultrasound scan at 10 MHz showed both lenses lying inferiorly in the vitreous. An ultrasound scan at 50 MHz allowed detailed examination of the anterior segment, including the iris and ciliary body, and showed two main features in each eye, including a lack of definition of ciliary processes, except in that quadrant toward which the pupil was displaced, and a membrane-like structure extending forward and attaching to the proximal pupil margin. The membrane passed over the tips of the ciliary processes to a more posterior origin. CONCLUSIONS: The only histologic reports of this condition are from the beginning of this century in the German literature. Ultrasonography at 50 MHz allows high-resolution in vivo imaging of anterior structures that are not clinically visible. The authors' findings in this case of ELeP are sufficiently different from those of non-ELeP-related aphakia to suggest that they are not solely due to aphakia. Furthermore, the authors' findings are very similar to the only histologic reports suggesting that the pupillary and lenticular ectopia results from mechanical tethering of the pupil with zonular disruption. This hypothesis has not been discussed in the recent literature.

Anterior Eye Segment↗

PubMed1998

On CNS repair and protection strategies: novel approaches with implications for spinal cord injury and Parkinson's disease.

In the adult mammalian central nervous system lost nerve cells are not replaced and there is no regeneration of injured axons in white matter. Together, these two facts mean that there are no spontaneous reparative mechanisms in operation. Instead, the adult central nervous system copes with the risks of injuries and diseases by protective encapsulation in bone, by a multitude of neuroprotective mechanisms, and finally by the fact that many important functions are represented by a much larger number of neurons than minimally needed. The long life expectancy of a human being nevertheless means that the risk that the central nervous system is affected by disease, injury or other forms of insults for which it cannot fully compensate is relatively high. Experimentally, two strategies are being pursued in order to develop ways of minimizing various forms of CNS damage, namely neuroprotective and reparative strategies. Here we present a possible reparative intervention applicable to spinal cord injury based on multiple white-to-gray matter peripheral nerve bridge grafts and work based on the specific role of Nurr1 for dopamine neuron development, suggesting that development of ligands to transcription factor might be a new inroad to neuroprotective treatments in Parkinson's disease.

Adult↗

PubMed1998

Inhibitors of catecholamine metabolizing enzymes cause changes in S-adenosylmethionine and S-adenosylhomocysteine in the rat brain.

Previous studies have shown that the biochemical changes that occur in parkinsonism are associated with disturbances in methylation reactions. Therefore, our hypothesis was that MAO and COMT inhibitors, which inhibit the metabolism of dopamine, might affect the methylation reaction. In the present study, we analyzed levels of S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) in brain homogenates from rats which had received a one-week treatment with tolcapone or phenelzine, inhibitors of COMT and MAO, respectively. Tolcapone treatment caused an increase in the levels of SAM (130% as compared with control animals, p < 0.001). In animals treated with phenelzine, the SAM levels were 78% of those of the controls (p < 0.05). SAH levels were slightly increased (115% as compared with controls, p < 0.05) in the phenelzine group, while they were unchanged in the tolcapone treated animals. Treatment with tolcapone decreased the catalytic activity of methionine adenosyltransferase (MAT) (from 15.4 +/- 1.6 to 11.3 +/- 1.4 pmol mg-1 min-1, p < 0.0001) while phenelzine treatment had no significant effect. In addition the transmethylation ratio (SAM/SAH) were significantly increased with tolcapone (120%, p < 0.05) and decreased with phenelzine (71%, p < 0.05) as compared to the controls. The essential finding of this paper was that brain SAM levels were reduced by MAO inhibition and enhanced by COMT inhibition.

Animals↗

PubMed1998

The National Diabetic Retinopathy Laser Treatment Audit. I. Maculopathy.

The National Diabetic Retinopathy Laser Treatment Audit is a prospective survey of laser treatment for diabetic retinopathy throughout the United Kingdom. This paper describes the methodology of the study and presents data on 546 patients who were undergoing their first photocoagulation treatment for diabetic maculopathy (without proliferative retinopathy) during a 2 month period in 1995. Validation of the level of participation, patient demographic features, sources of referral, the level of systematic screening and waiting times are described. Maculopathy was detected as a result of systematic screening in 65.2%, whilst 12.3% of cases presented symptomatically. The percentage of cases treated within 8 weeks of listing was 83.1%, whilst 7% waited for more than 12 weeks for their laser treatment. The retinopathy features and the type of treatment given are also described. The maculopathy was said to be predominantly exudative in nature in 69.8% of cases, and 96.2% of these eyes were treated with focal macular laser. The maculopathy was said to be diffusely oedematous in nature in 8.6% of cases, and 78.7% of these eyes were treated with grid macular laser.

Adult↗