Biomedical subjects

J C Partridge

Publications and source records attributed to J C Partridge.

At least 37 records · Page 2Linked to original sources

PubMed1999

Proton MR spectroscopy for the evaluation of brain injury in asphyxiated, term neonates.

BACKGROUND AND PURPOSE: Neurologic and developmental outcomes of asphyxiated, term neonates are difficult to predict applying clinical or laboratory criteria. In this study, we investigated the association of MR spectroscopy (MRS) results with neurodevelopmental status at age 12 months. METHOD: Thirty-one term neonates, who were enrolled in a prospective study of the utility of MR imaging for the determination of neurologic and developmental status, underwent single-voxel proton MRS of the basal nuclei and intervascular boundary zones. Ratios of lactate, choline, creatine, and N-acetylaspartate (NAA) peaks were calculated and tested for association with neuromotor scores and Mental Development Index of the Bayley Scores of Infant Development obtained at age 12 months. RESULTS: Elevated lactate and diminished NAA were the most common findings in infants with neurologic and developmental abnormalities at age 12 months. Although many ratios had statistically significant associations with outcome (P<.05), the highest significance was obtained with lactate/choline ratios in the basal nuclei. A false-positive finding was seen in a patient who was born after a 36-week gestation period (high lactate/choline but normal neurodevelopmental status at 12 months) and in three patients with apparent watershed injury (high watershed lactate/choline but normal neurodevelopmental status at 12 months). A false-negative MRS finding (normal lactate/choline but abnormal outcome) was seen in a patient who had an apparent prenatal injury. CONCLUSION: Proton MRS appears to be a useful tool for assessing brain injury in neonates who have suffered hypoxia or ischemia. Correlation with gestational age and imaging findings are essential for proper interpretation of the spectra. Patients with apparent watershed injuries may have normal neurodevelopmental status at age 12 months.

Aspartic Acid↗

PubMed1998

Switch in rod opsin gene expression in the European eel, Anguilla anguilla (L.).

The rod photoreceptors of the European eel, Anguilla anguilla (L.), alter their wavelength of maximum sensitivity (lambda max) from c.a. 523 nm to c.a. 482 nm at maturation, a switch involving the synthesis of a new visual pigment protein (opsin) that is inserted into the outer segments of existing rods. We artificially induced the switch in rod opsin production by the administration of hormones, and monitored the switch at the level of mRNA accumulation using radiolabelled oligonuleotides that hybridized differently to the two forms of eel rod opsin. The production of the deep-sea form of rod opsin was detected 6 h after the first hormone injection, and the switch in rod opsin expression was complete within four weeks, at which time only the mRNA for the deep-sea opsin was detectable in the retinal cells. It is suggested that this system could be used as a tractable model for studying the regulatory control of opsin gene expression.

Anguilla↗

PubMed1998

Management of extremely low birth weight infants: perceptions of viability and parental counseling practices.

OBJECTIVE: To determine physician opinions, parental counseling, and medical practices for extremely low birth weight (LBW) infants. METHODS: A retrospective survey was sent in August 1996 to 450 California physicians practicing obstetrics. RESULTS: There was a 41% response rate. The mean thresholds for antenatal steroid administration, cesarean delivery for fetal distress and delivery room resuscitation were gestational age between 23 and 24 weeks and weight close to 500 g. Most obstetricians counsel parents regarding survival, resuscitation, and possible death in the delivery room before delivery of an extremely LBW infant. Just over 60% of obstetricians believe that parents have a role in deciding not to resuscitate an infant born at 22 weeks' gestation, this decreases to less than 50% at 24 weeks, and decreases further to less than 30% by 26 weeks' gestation. Just over 40% of obstetricians report their counseling is affected by pediatric opinion, 33% by previous maternal perinatal losses, and less than 20% by maternal drug use or lack of prenatal care, and young maternal age. Language barriers, parental education level, and family insurance affect treatment options in less than 10% of obstetricians. CONCLUSION: Obstetric opinions about delivery room resuscitation of extremely LBW infants are influenced by birth weight and gestational age thresholds, infant, and parental factors. There is a limited willingness by physicians to allow a parental role in decision making in the delivery room for extremely LBW infants.

Adult↗

PubMed1998

The eyes of deep-sea fish. I: Lens pigmentation, tapeta and visual pigments.

Deep-sea fish, defined as those living below 200 m, inhabit a most unusual photic environment, being exposed to two sources of visible radiation; very dim downwelling sunlight and bioluminescence, both of which are, in most cases, maximal at wavelengths around 450-500 nm. This paper summarises the reflective properties of the ocular tapeta often found in these animals, the pigmentation of their lenses and the absorption characteristics of their visual pigments. Deep-sea tapeta usually appear blue to the human observer, reflecting mainly shortwave radiation. However, reflection in other parts of the spectrum is not uncommon and uneven tapetal distribution across the retina is widespread. Perhaps surprisingly, given the fact that they live in a photon limited environment, the lenses of some deep-sea teleosts are bright yellow, absorbing much of the shortwave part of the spectrum. Such lenses contain a variety of biochemically distinct pigments which most likely serve to enhance the visibility of bioluminescent signals. Of the 195 different visual pigments characterised by either detergent extract or microspectrophotometry in the retinae of deep-sea fishes, ca. 87% have peak absorbances within the range 468-494 nm. Modelling shows that this is most likely an adaptation for the detection of bioluminescence. Around 13% of deep-sea fish have retinae containing more than one visual pigment. Of these, we highlight three genera of stomiid dragonfishes, which uniquely produce far red bioluminescence from suborbital photophores. Using a combination of longwave-shifted visual pigments and in one species (Malacosteus niger) a chlorophyll-related photosensitizer, these fish have evolved extreme red sensitivity enabling them to see their own bioluminescence and giving them a private spectral waveband invisible to other inhabitants of the deep-ocean.

Animals↗

PubMed1998

Seven retinal specializations in the tubular eye of the deep-sea pearleye, Scopelarchus michaelsarsi: a case study in visual optimization.

The deep-sea pearleye, Scopelarchus michaelsarsi (Scopelarchidae) is a mesopelagic teleost with asymmetric or tubular eyes. The main retina subtends a large dorsal binocular field, while the accessory retina subtends a restricted monocular field of lateral visual space. Ocular specializations to increase the lateral visual field include an oblique pupil and a corneal lens pad. A detailed morphological and topographic study of the photoreceptors and retinal ganglion cells reveals seven specializations: a centronasal region of the main retina with ungrouped rod-like photoreceptors overlying a retinal tapetum; a region of high ganglion cell density (area centralis of 56.1 x 10(3) cells per mm2) in the centrolateral region of the main retina; a centrotemporal region of the main retina with grouped rod-like photoreceptors; a region (area giganto cellularis) of large (32.2+/-5.6 microm2), alpha-like ganglion cells arranged in a regular array (nearest neighbour distance 53.5+/-9.3 microm with a conformity ratio of 5.8) in the temporal main retina; an accessory retina with grouped rod-like photoreceptors; a nasotemporal band of a mixture of rod- and cone-like photoreceptors restricted to the ventral accessory retina; and a retinal diverticulum comprised of a ventral region of differentiated accessory retina located medial to the optic nerve head. Retrograde labelling from the optic nerve with DiI shows that approximately 14% of the cells in the ganglion cell layer of the main retina are displaced amacrine cells at 1.5 mm eccentricity. Cryosectioning of the tubular eye confirms Matthiessen's ratio (2.59), and calculations of the spatial resolving power suggests that the function of the area centralis (7.4 cycles per degree/8.1 minutes of arc) and the cohort of temporal alpha-like ganglion cells (0.85 cycles per degree/70.6 minutes of arc) in the main retina may be different. Low summation ratios in these various retinal zones suggests that each zone may mediate distinct visual tasks in a certain region of the visual field by optimizing sensitivity and/or resolving power.

Animals↗

PubMed1998

Prediction of neuromotor outcome in perinatal asphyxia: evaluation of MR scoring systems.

PURPOSE: We developed a scoring system for the assessment of perinatal asphyxia as depicted on MR images. METHODS: Four scoring systems were derived to evaluate MR images obtained in asphyxiated neonates: the basal ganglia (BG) score, the watershed (W) score, the combined basal ganglia/watershed (BG/W) score, and the sum of the BG and W scores, the summation (S) score. In addition, three MR sequences, T1-weighted, first-echo T2-weighted, and second-echo T2-weighted, were assessed for each patient for each scoring system. Neuromotor examinations were performed at ages 3 and 12 months, and cognitive development was tested at age 12 months. Statistical analysis was then performed to test the relationship between the MR scores and the outcome scores. RESULTS: The BG/W score, obtained with the first-echo T2-weighted sequence, was the most useful overall score for predicting neuromotor outcome at 3 and 12 months and cognitive outcome at 12 months. T1-weighted and first-echo T2-weighted sequences showed a stronger association with outcome in patients imaged during the first postnatal week, whereas second-echo T2-weighted sequences showed a stronger association with outcome in patients imaged during the second postnatal week. CONCLUSION: It appears that, with the use of the BG/W score, MR imaging discriminates accurately between patients with good and poor neuromotor and cognitive outcome at 3 and 12 months. In terms of our scoring systems, the first-echo T2-weighted sequence appears to discriminate best between patients with good and poor 3- and 12-month outcomes. Proper use of the imaging sequences and scoring systems described in this article can increase the knowledge base upon which treatment decisions are made in asphyxiated neonates.

Asphyxia Neonatorum↗

PubMed1997

Ultraviolet plumage colors predict mate preferences in starlings.

Avian plumage has long been used to test theories of sexual selection, with humans assessing the colors. However, many birds see in the ultraviolet (<400 nm), to which humans are blind. Consequently, it is important to know whether natural variation in UV reflectance from plumage functions in sexual signaling. We show that female starlings rank males differently when UV wavelengths are present or absent. Principal component analysis of approximately 1300 reflectance spectra (300-700 nm) taken from sexually dimorphic plumage regions of males predicted preference under the UV+ treatment. Under UV- conditions, females ranked males in a different and nonrandom order, but plumage reflectance in the human visible spectrum did not predict choice. Natural variation in UV reflectance is thus important in avian mate assessment, and the prevailing light environment can have profound effects on observed mating preferences.

Animals↗

PubMed1997

Mechanisms of wavelength tuning in the rod opsins of deep-sea fishes.

The main object of this study was to investigate the molecular basis for changes in the spectral sensitivity of the visual pigments of deep-sea fishes. The four teleost species studied, Hoplostethus mediterraneus, Cataetyx laticeps, Gonostoma elongatum and Histiobranchus bathybius, are phylogenetically distant from each other and live at depths ranging from 500 to almost 5000 m. A single fragment of the intronless rod opsin gene was PCR-amplified from each fish and sequenced. The wavelength of peak sensitivity for the rod visual pigments of the four deep-sea species varies from 483 nm in H. mediterraneus and G. elongatum to 468 nm in C. laticeps. Six amino acids at sites on the inner face of the chromophore-binding pocket formed by the seven transmembrane a-helices are identified as candidates for spectral tuning. Substitutions at these sites involve either a change of charge, or a gain or loss of a hydroxyl group. Two of these, at positions 83 and 292, are consistently substituted in the visual pigments of all four species and are likely to be responsible for the shortwave sensitivity of the pigments. Shifts to wavelengths shorter than 480 nm may involve substitution at one or more of the remaining four sites. None of the modifications found in the derived sequences of these opsins suggest functional adaptations, such as increased content of hydroxyl-bearing or proline residues, to resist denaturation by the elevated hydrostatic pressures of the deep sea. Phylogenetic evidence for the duplication of the rod opsin gene in the Anguilliform lineage is presented.

Adaptation, Physiological↗

PubMed1997

Tubular eyes of deep-sea fishes: a comparative study of retinal topography.

The world's deep oceans are home to a number of teleosts with asymmetrical or tubular eyes. These immobile eyes possess large spherical lenses and subtend a large binocular visual field directed either dorsally or rostrally. Derived from a lateral non-tubular eye, the tubular eye is comprised of a thick main retina, subserving the rostrally or dorsally directed binocular visual field, and a thin accessory retina subserving, the lateral, monocular visual field. The main retina is thought to receive a focussed image, while the accessory retina is too close to the lens for a focussed image to be received. Several species also possess retinal diverticula, which are small evaginations of differentiated retina located in the rostrolateral wall of the eye and thought to increase the visual field. In order to investigate the spatial resolving power of these retinae (main, accessory and diverticulum), the distribution of cells within the ganglion cell layer was analysed from retinal wholemounts and sectioned material in ten species representing four genera. In all species, the main retina possesses a marked increase in cell density towards a specialised retinal region (area centralis), with a centro-peripheral gradient range between 7:1 and 60:1 and a peak density range of between 30 and 55 x 10(3) cells per mm2. The accessory retinae and the transitional zone between the main and accessory retinae possess relatively low cell densities (between 1 and 10 x 10(3) cells per mm2) and lack an area centralis. Retinal diverticula examined in four species possess mean ganglion cell densities of between 7.2 and 109.4 x 10(3) cells per mm2. Analyses of soma areas show that the ganglion cell layer of most species possesses cells with areas in a range of 8.0 to 15.4 microns2 in the main retina and between 15.1 and 17.4 microns2 in the accessory retina. The peak spatial resolving power of the main retina of the ten species varies from 4.1 to 9.1 cycles per degree. The positions of the retinal areae centrales relative to each species' binocular visual field are discussed in relation to what is known of feeding behaviour of these fishes in the deep-sea.

Animals↗

PubMed1997

Death in the intensive care nursery: physician practice of withdrawing and withholding life support.

OBJECTIVE: To determine the frequency of selective nontreatment of extremely premature, critically ill, or malformed infants among all infant deaths in a level III intensive care nursery (ICN) and to determine the reasons documented by neonatologists for their decisions to withdraw or withhold life support. METHODS: This was a descriptive study based on review of the medical records of all 165 infants who died at a university-based level III ICN during 3 years. We determined whether each death had occurred despite the use of all available technologies to keep the infant alive or whether these were withheld or withdrawn, thereby leading to the infant's death. We also determined whether neonatologists documented either "futility" or "quality of life" as a reason to limit medical interventions. RESULTS: One hundred sixty-five infants died among the 1609 infants admitted during the study period. One hundred eight infant deaths followed the withdrawal of life support, 13 deaths followed the withholding of treatment, and 44 deaths occurred while infants continued to receive maximal life-sustaining treatment. For 90 (74%) of the 121 deaths attributable to withholding of withdrawal of treatment, physicians cited that death was imminent and treatment was futile. Quality-of-life concerns were cited by the neonatologists as reasons to limit treatment in 62 (51%). Quality of life was the only reason cited for limiting treatment for 28 (23%) of the 121 deaths attributable to withholding or withdrawal of treatment. CONCLUSIONS: The majority of deaths in the ICN occurred as a result of selective nontreatment by neonatologists, with few infants receiving maximal support until the actual time of death. Neonatologists often documented that quality-of-life concerns were considered in decisions to limit treatment; however, the majority of these decisions were based on their belief that treatment was futile. Prospective studies are needed to elucidate the determinants of neonatologists' practice decisions of selective nontreatment for marginally viable or damaged infants.

Decision Making↗

PubMed1997

Analgesia for dying infants whose life support is withdrawn or withheld.

OBJECTIVE: To determine the frequency of opiate analgesia administration to infants when life support is discontinued and to determine whether infant characteristics, such as birth weight and diagnosis, or the physician's reasons for discontinuing life support influence either the decision to provide opioid agents or the dosages administered. METHODS: We reviewed all 165 deaths in a 3-year period at a university-based level III intensive care nursery. Of the 121 deaths attributable to withdrawal or withholding of mechanical ventilation and/or extracorporeal membrane oxygenation, we ascertained whether opioid analgesics (morphine sulfate [MS] or fentanyl) were administered either concurrent with or after life-support withdrawal and at what doses. We examined whether these end-of-life practices varied according to birth weight, diagnoses, and the reasons documented by the neonatologist for discontinuing life support. RESULTS: Opioid analgesia was provided to 84% of infants as their life support was either withheld or withdrawn. Infants with necrotizing enterocolitis and major anomalies or chromosomal disorders were more likely to be given opiates than infants with other diagnoses. Birth weight was not different for infants who received opiates compared with those who were not given opiates. Opioid analgesia was provided to all 18 infants for whom physicians documented the patients' suffering as a reason to discontinue life support. Sixty-four percent of infants who received opiates were given doses in the usual pharmacologic range of 0.1 to 0.2 mg/kg MS. Of the 36 infants given more than 0.2 mg/kg MS, all but 2 were receiving ongoing treatment with opioid agents. CONCLUSIONS: In most cases of withholding or withdrawal of life support in critically ill infants, neonatologists provided opioid analgesia to these infants at the end of life, despite the potential respiratory depression of opioid agents in infants whose respiratory support is discontinued.

Analgesia↗

PubMed1997

MR contrast enhancement of the normal neonatal brain.

PURPOSE: To determine the pattern of enhancement on contrast-enhanced MR studies of the brain in neonates. METHODS: Contrast-enhanced brain MR studies of 16 neonates were reviewed retrospectively. All infants had normal neonatal courses, normal noncontrast MR findings, and normal neurologic examinations at age 12 months. All enhancing regions within the brain, dura, calvaria, and orbits were recorded. An enhancement factor, F = (Ic-Ip)/Ip, was calculated from region-of-interest intensity measurements in five regions of each hemisphere (basal ganglia, thalami, and three hemispheric locations), where Ic was signal intensity after contrast administration and Ip was the noncontrast signal intensity for each region. RESULTS: Enhancement was detected in the choroid plexus, pituitary infundibula, pineal glands, dura, veins and venous sinuses, cranial sutures, and irises of the orbital globes. No enhancement of the brain parenchyma was detected by visual inspection, although some change in signal intensity of the cerebral parenchyma was detected by the region-of-interest intensity measurements, with enhancement factors ranging from 0 to 0.08 (mean, 0.04). No consistent regional variation in enhancement was detected. Because the degree of enhancement was identical to that in the normal adult brain, the slight enhancement detected was attributed to contrast material in capillaries and small venules. CONCLUSION: In addition to the expected findings of enhancement of the pituitary stalk, the pineal gland, the choroid plexus, the dura, and the cerebral veins, we detected enhancement of the calvarial sutures and ocular irises. No evidence of enhancement of the cerebral parenchyma was detected, suggesting that the blood-brain barrier to gadolinium chelates is intact in the neonatal brain.

Adult↗

PubMed1996

Neurologic and ophthalmologic findings in children exposed to cocaine in utero.

We studied a cohort of 73 children exposed to cocaine in utero to characterize the spectrum of neurologic and ophthalmologic abnormalities; 36 children with no documented in utero drug exposure were selected as a control group. Most referrals of cocaine-exposed children to the child neurologist were made in the 1st year of life (81%). Reasons for referral were hypertonia (29%), seizures (22%), developmental delay (11%), tremulousness (11%), and hypotonia (4%). The most common abnormal finding in the cocaine-exposed children was hypertonia/hyperreflexia (63%), which was rarely seen in the control group. In addition, hypertonia/hyperreflexia was underdiagnosed by referring physicians. Similarly, hypotonia was seen on neurologic examination of cocaine-exposed children more frequently than documented by referral (16% versus 4%). Hypotonia was rarely seen in the control group. Twelve (43%) of 28 cocaine-exposed children seen by a pediatric ophthalmologist had structural ophthalmologic abnormalities. Neurologic and ophthalmologic findings suggesting structural lesions of the nervous system must be considered in cocaine-exposed children.

Child↗

PubMed1995

The molecular basis for the green-blue sensitivity shift in the rod visual pigments of the European eel.

When the European eel matures sexually and migrates back to deep sea breeding grounds the visual pigments in its rod photoreceptors change from being maximally sensitive to green light to being maximally sensitive to blue light. In part, this change in sensitivity is due to a change in the opsin component of the visual pigment molecule. We used hormone injection to induce these developmental changes in a group of eels and from these animals an opsin coding region was cloned and sequenced using cDNA made from retinal mRNA. From the retinae of hormone-injected eels and those not injected with hormones, distinct opsin mRNAs were isolated. These mRNAs encode two rod opsin proteins that are very similar but have significant amino acid substitutions in key positions that are likely to be involved in spectral tuning of the eel green and blue sensitive rod visual pigment molecules.

Amino Acid Sequence↗

PubMed1995

The consequences of a positive prenatal HIV antibody test for women.

As more women of childbearing age are affected by the human immunodeficiency virus (HIV), many providers have demanded routine perinatal HIV screening, arguing that the medical benefits of testing outweigh the socioeconomic, medical, and psychological risks of a positive HIV test for women. In this primarily urban poor population, we used a semistructured interview to evaluate differences in health care discrimination, economic losses, risk behaviors, relationships changes, and psychological status in 20 HIV-positive and 20 HIV-negative mothers matched for HIV risk, race, income, and delivery date. Many (35%) seropositive and no seronegative women cited health care discrimination due to HIV status. Although seropositive women reported greater satisfaction with social support from friends (100%) and family (80%), many women had not disclosed their HIV status to any friends (65%) or family (25%), indicating fear of abandonment. Only 56% of HIV positive and 44% of seronegative women knew their partners' HIV status, and many HIV-positive and HIV-negative women reported having sex without condoms after the HIV test. Mean standardized anxiety (p < 0.05) and depression scores were higher in seropositive women. Despite added social support and medical treatments, HIV-positive women showed higher levels of health care discrimination, personal isolation, and psychological sequelae than their seronegative counterparts. As the medical benefits to prenatal HIV testing increase, we will need to develop focused medical, social, and mental health services addressing the needs of HIV-positive women.

Adult↗

PubMed1995

Patterns and implications of MR contrast enhancement in perinatal asphyxia: a preliminary report.

PURPOSE: To determine the presence and location of MR contrast enhancement in infants with perinatal asphyxia and to evaluate the utility of enhancement in assessing extent of brain damage. METHODS: Precontrast and postcontrast MR examinations within the first 10 days of life were evaluated in 10 infants with suspected hypoxic-ischemic birth injury. Findings were correlated with clinical birth history and short-term neurologic follow-up. RESULTS: All four infants with MR signal abnormalities and contrast enhancement in the basal ganglia and brain stem had early seizures and profound neurologic deficits at early follow-up. Two infants had abnormal scans but no contrast enhancement; one with MR signal abnormality within the basal ganglia is neurologically healthy at 10-month follow-up, whereas the other, in status epilepticus at the time of imaging at age 2 days, died. Two infants with minimal parasagittal subcortical white matter enhancement had no early seizure activity and only mild developmental delay at early follow-up. Two infants with normal precontrast and postcontrast MR had no early seizures and remain healthy at early follow-up, despite initial clinical parameters similar to more severely injured infants. CONCLUSION: Although the number of patients is small, our results indicate that the presence of contrast enhancement in asphyxiated neonates may indicate more severe brain damage and, hence, a poorer prognosis.

Acid-Base Equilibrium↗

PubMed1993

Effect of bundling and high environmental temperature on neonatal body temperature.

OBJECTIVE: The effect of bundling and ambient heat on newborn body temperature has not been systematically studied. It was hypothesized that bundling and warm environments can elevate the newborn's temperatures to the range that would prompt clinical concern of neonatal sepsis. METHODS: Twenty well, term newborns more than 1 day old were assigned to the control group (one blanket; 24.0 degrees C room) or the experimental group (five blankets and hat; 26.6 degrees C room). Continuous rectal probe temperatures were monitored over a 2 1/2-hour period. RESULTS: There were 8 control and 12 experimental newborns. The mean change in rectal temperature after 2 1/2 hours was -0.04 degrees C (SD +/- 0.23) in control newborns and +0.56 degrees C (SD +/- 0.12) in the treatment group (P < .0001, t test). Temperatures in the treatment group rose, after an initial half-hour lag, at a linear rate of 0.27 degrees C per hour without a plateau. Two newborns reached 38.0 degrees C, a rectal temperature that may raise concern of infection. CONCLUSIONS: Bundling and warm environments can elevate newborn body temperature to the "febrile" range in this age group. Physicians treating neonates with elevated temperature should ask about bundling and environmental conditions to differentiate endogenous from exogenous "fevers."

Body Temperature↗

PubMed1992

The absorbance spectrum and photosensitivity of a new synthetic "visual pigment" based on 4-hydroxyretinal.

The firefly squid, Watasenia scintillans, is the only animal known to possess a visual pigment in which the chromophore is 4-hydroxyretinal. This paper describes the absorbance spectrum and some properties of a synthetic "A4" visual pigment generated from bovine opsin and 4-hydroxyretinal. The absorbance spectrum of this pigment is compared with (a) bovine rhodopsin and (b) a rhodopsin template with the same lambda max as the synthetic visual pigment. The A4 pigment is shown to have an absorbance spectrum that is almost identical to that of a rhodopsin template. It is also shown that the photosensitivity and thermal stability of the A4 pigment, dispersed in detergent micelles, is essentially similar to that of rhodopsin.

Animals↗