Adult xanthogranulomatous disease of the orbit and ocular adnexa: new immunohistochemical findings and clinical review

BACKGROUND/AIMS

Adult xanthogranulomatous disease involving the ocular tissues is rare and poorly understood. Adult onset xanthogranuloma (AOX), adult onset asthma and periocular xanthogranuloma (AAPOX), necrobiotic xanthogranuloma (NBX), and Erdheim-Chester disease (ECD) are the four syndromes within this disorder, which is diagnosed by characteristic histopathology. Experience with eight cases prompted a multi-institutional effort to study the histopathology, immunohistochemistry, clinical findings, and systemic associations in this disorder.

METHODS

22 cases, including histopathological slides, were compiled. Published reports were identified by an English language Medline search (1966-2005) and review of reference citations. Each case in this series and the literature was classified as one of four syndromes and then analysed for age onset, sex, skin xanthoma, orbital location, immune dysfunction, internal organ and bone lesions, treatment, and outcome. The histopathology in each of these cases was reviewed by two pathologists. Immunhistochemical stains (CD3, CD4, CD8, L26) were performed in 14 cases where unstained slides were available.

RESULTS

137 cases were compiled. There was no sex or age difference between syndromes. AOX, AAPOX, NBX affect the anterior orbit, ECD tends to be diffuse and intraconal. Skin lesions are found in all the syndromes. Immune dysfunction was noted in all cases of AAPOX and NBX; 11% of NBX and all ECD patients had internal organ disease. Treatment included surgery, corticosteroids, other chemotherapeutic agents, radiotherapy, and combinations of these. No AOX or AAPOX deaths occurred; 66% of ECD patients died. All 22 cases had xanthoma cells; most had Touton giant cells. Lymphocytes were present in all cases and occurred as aggregates (mostly in AAPOX) or diffuse populations mixed with fibroblasts (mostly in ECD). Immunohistochemistry revealed the majority of these to be CD8+. Necrosis was most marked in NBX.

CONCLUSION

Adult xanthogranuloma of the orbit is rare, making prospective evaluation or meta-analysis impossible. The best treatment is unknown but seems to be with multiagent chemotherapy guided by histopathological, immunohistochemical, and systemic findings.

Reversal of dysthyroid optic neuropathy following orbital fat decompression

AIMS

To document the successful treatment of five patients with dysthyroid optic neuropathy by orbital fat decompression instead of orbital bone decompression after failed medical therapy.

METHODS

Eight orbits of five patients with dysthyroid optic neuropathy were selected for orbital fat decompression as an alternative to bone removal decompression. Treatment with systemic corticosteroids and/or orbital radiotherapy was either unsuccessful or contraindicated in each case. All patients satisfied clinical indications for orbital bone decompression to reverse the optic neuropathy. High resolution computerised tomographic (CT) scans were performed in all cases and in each case showed signs of enlargement of the orbital fat compartment. As an alternative to bone decompression, orbital fat decompression was performed on all eight orbits.

RESULTS

Orbital fat decompression was performed on five patients (eight orbits) with optic neuropathy. Optic neuropathy was reversed in all cases. There were no cases of postoperative diplopia, enophthalmos, globe ptosis, or anaesthesia. All patients were followed for a minimum of 1 year.

CONCLUSIONS

In a subset of patients with an enlarged orbital fat compartment and in whom extraocular muscle enlargement is not the solitary cause of optic neuropathy, fat decompression is a surgical alternative to bony decompression.

Orbital fat removal. Decompression for Graves orbitopathy

BACKGROUND

Orbital decompression has been used to describe surgical procedures that remove some portion of the orbital walls to reduce pressure on the orbital contents. Substantial morbidity associated with these procedures includes infraorbital anesthesia, worsened extraocular motility, globe displacement, and blindness. The authors believe that orbital contents also may be decompressed by removing orbital fat.

METHODS

Eighty-one patients with nonactive Graves orbitopathy were selected for orbital fat decompression based on the presence of proptosis and associated signs and symptoms to avoid bone removal. Soft-tissue analysis by computed tomography (CT) scan showed distended pockets of fat extending into the intraconal space, which were removed through medial-upper and lateral-lower anterior orbitotomies. Decompression with bone removal was reserved for those few patients with compressive optic neuropathy unresponsive to medical treatment and those patients with residual deforming exophthalmos after fat removal.

RESULTS

One hundred fifty-eight fat decompressions were performed on 81 patients over 9 years. The authors measured an average reduction in proptosis of 1.8 mm (range, 0-6.0 mm). The greatest average reduction in proptosis (3.3 mm) was produced in patients with preoperative Hertel measurements of greater than 25.0 mm. Morbidity was limited to temporary motility impairment of the inferior oblique in two patients.

CONCLUSION

The concept of orbital decompression can include removal of orbital fat to reduce proptosis, eliminate symptoms, and improve appearance with far less morbidity than when bone decompression is used as the primary decompressive procedure.

Treatment of acute Graves orbitopathy

The therapeutic options for the treatment of acute Graves orbitopathy include high-dose oral corticosteroids, surgical decompression, and radiotherapy. The former two treatments are associated with significant morbidity. Although there have been a number of reports of the efficacy of radiotherapy, its role in the management of this disease is still questioned. The authors reviewed 84 cases of acute Graves orbitopathy treated with either high-dose systemic corticosteroids or radiotherapy (2000 rad to each involved orbit). Radiotherapy resulted in significant improvement in subjective and objective signs of orbital congestion and was more effective than high-dose corticosteroids in relieving compressive optic neuropathy. Of the patients with compressive optic neuropathy, only 1 of 29 treated with radiotherapy required surgical decompression, whereas, 6 of 16 treated with corticosteroids required surgery. This study suggests that radiotherapy has greater efficacy and fewer complications than high-dose systemic corticosteroids in the treatment of acute Graves orbitopathy.

Management of conjunctival cicatrizing diseases and severe ocular surface dysfunction

Physical or chemical injuries, infections, immunologic oculocutaneous disorders, drugs, and various systemic disorders may cause scarring of the conjunctiva and disturbances of the ocular surface. Trichiasis, lid margin malposition, and dry eye may result in persistent ocular irritation. The cornea may be primarily or secondarily involved. If severe, disturbances of the ocular surface may lead to significant visual impairment. Thorough evaluation of patients and of the underlying disease process is required for optimal management. Treatment may be challenging and should be comprehensive, combining medical measures and surgical correction of structural changes. Suppression of exogenous irritants, treatment of dry eye, antiinflammatory therapy, and immunosuppressants are paramount to control the underlying disease and allow optimal surgical results. Surgical correction of trichiasis and lid margin malposition, conjunctival grafting, mucous membrane transplantation, limbal stem cell transplantation, amniotic membrane transplantation, and penetrating keratoplasty help reestablish a physiologic ocular surface. Severe cases may require keratoprosthetics for visual rehabilitation. Corneal ulceration or perforation requires prompt attention to maintain ocular integrity. Special measures should be considered for patients who require cataract or glaucoma surgery.

Orbital lymphangioma. Correlation of magnetic resonance images and intraoperative findings

BACKGROUND

Orbital lymphangiomas generally are invasive, slow-growing lesions that can produce proptosis, motility impairment, and compressive optic neuropathy. Successful surgical management requires detailed preoperative radiologic imaging with the capacity to determine the location and size of the tumors, the presence of cystic or solid components, and extent of infiltration of the tumor into normal orbital structures.

METHODS

The records of 12 patients with orbital lymphangioma were reviewed with attention to the clinical, radiologic, operative, and histologic findings.

RESULTS

Preoperative magnetic resonance imaging (MRI) produced highly detailed renderings of the orbital mass that were both diagnostic and predictive of the intraoperative findings. Magnetic resonance imaging was particularly sensitive to the presence of cysts within the tumor and was able to predict the contents of the cysts.

CONCLUSION

Using preoperative MRI, a more detailed and accurate surgical plan can be formulated than with any other noninvasive technique.

Streptococcal gangrene of the eyelids and orbit

PURPOSE

Streptococcal gangrene, also termed streptococcal necrotizing fasciitis, is resurgent but remains exceedingly rare. Ophthalmologists and dermatologists must be aware of streptococcal gangrene, as eyelids are the most commonly affected area of the head and neck.

METHODS

We studied two cases of streptococcal gangrene of the orbit with clinical manifestations indistinguishable from common nonnecrotizing orbital cellulitis.

RESULTS

Infection progressed with dramatic rapidity to produce eyelid necrosis, respiratory failure, sepsis, and severe permanent visual loss caused by ophthalmic artery occlusions. Histopathologic analysis disclosed vascular thrombosis, necrosis, acute inflammation, and the presence of gram-positive cocci. Cultures grew heavy group A beta hemolytic Streptococcus. The first patient was infected with M type 1 carrying exotoxins A and B. The second patient was also infected with Streptococcus carrying exotoxin A.

CONCLUSION

Early diagnosis of this life-threatening infection is of paramount importance because survival may depend on early surgical debridement.

The role of postoperative irradiation in the management of sphenoid wing meningiomas. A preliminary report

PURPOSE

To determine whether postoperative radiation therapy decreases recurrence rates in subtotally excised and recurrent sphenoid wing meningiomas.

METHODS

Patients with primary subtotally excised and recurrent sphenoid wing meningiomas who underwent surgery between 1981 and 1994 (n = 105) were prospectively followed for recurrence. Postoperative radiation was not recommended in patients who had complete excision; therefore, their recurrence rates were not evaluated in this study. Patients with malignant meningiomas also were excluded from analysis. Recurrence was defined as evidence of tumor growth on neuroimaging with or without clinical symptoms.

RESULTS

Follow-up information was available for 86 patients; 69 had primary subtotally excised tumors and 17 had recurrent tumors. Follow-up information was unavailable in the remaining 19 patients. Tumor location and histopathology, type of surgery performed, and patient sex and age were similar in the irradiated and nonirradiated subgroups. Postoperative irradiation was delivered to 31 patients with primary tumors and 11 with recurrent tumors; none of these 42 patients had recurrence during a mean observation period of 4.2 and 3.5 years, respectively. The nonirradiated group consisted of 38 patients with primary tumors and 6 with recurrent tumors; 16 of 18 patients who had primary meningiomas had a recurrence and 5 of 6 who had recurrent tumors had another relapse (mean interval between resection and recurrence, 4.4 years and 14 months, respectively).

CONCLUSIONS

Postoperative radiation appeared to delay recurrence in subtotally excised and recurrent sphenoid wing meningiomas during the time frame of this study.

Choristoma of the optic nerve and chiasm

A 21-year-old patient with a biopsy-proved choristomatous malformation of the optic nerve and chiasm is presented. The patient experienced progressive unilateral vision loss and optic atrophy. A gadolinium-enhanced magnetic resonance image demonstrated chiasmal involvement that was not evident on computed tomographic scan or visual field testing. We believe this is the third reported case of a choristomatous malformation of the optic nerve and chiasm and the first report of magnetic resonance imaging findings.

Prominent proptosis in childhood thyroid eye disease

BACKGROUND

Orbital signs and symptoms occur in approximately one half of children with Graves disease, but the symptoms are usually minor and limited to the eyelids. Prominent proptosis is uncommon in children with this disorder.

METHODS

Review of eight children with prominent proptosis associated with thyroid eye disease. Four patients were treated at the Children's Hospital of Philadelphia, the other four at the Columbia Presbyterian Medical Center.

RESULTS

At initial presentation, children ranged in age from 3 to 16 years. There were five girls and three boys. Seven of eight children had hyperthyroidism at ophthalmic presentation. Four patients had restrictive myopathy, and all of the seven patients who underwent neuroimaging had extraocular muscle enlargement. Five patients were treated with lubrication. Two underwent orbital fat decompression. One patient had thyroid eye disease and myasthenia gravis.

CONCLUSIONS

Proptosis in childhood thyroid eye disease usually is associated with a hyperthyroid state. The proptosis may be dramatic, but corneal exposure and restrictive myopathy are seen in only some of the patients. Neuroimaging shows enlarged extraocular muscles. Most children with this complication can be treated conservatively with topical lubrication, but orbital fat decompression may be considered in patients with more advanced conditions.

Varicella-zoster virus retrobulbar optic neuritis in a patient with human immunodeficiency virus

PURPOSE

To determine the cause of bilateral retrobulbar optic neuritis followed by progressive outer retinal necrosis in a patient with human immunodeficiency virus (HIV).

METHODS

Extensive ophthalmologic, neurologic, infectious disease, rheumatologic, and radiologic examinations were performed.

RESULTS

Cerebrospinal fluid samples taken after the onset of bilateral retrobulbar optic neuritis and before the development of clinical progressive outer retinal necrosis disclosed varicella-zoster virus from polymerase chain reaction and viral culture.

CONCLUSION

Ophthalmologists and neurologists should consider varicella-zoster virus optic neuritis as a potential precursor of progressive outer retinal necrosis and as a cause of retrobulbar optic neuritis in patients infected with HIV.

Evaluation of a collagen/hydroxylapatite implant for orbital reconstructive surgery

A variety of autogenous and alloplastic materials have been used to correct enophthalmos. Hydroxylapatite (HA), is a calcium-phosphate-based compound that has been extensively studied as a bone replacement material. We studied the properties of a new dense particulate form of HA in a collagen matrix (PFC/HA) implanted in the subperiosteal space of ten rabbit orbits for a period of 6 months. All animals were studied with pre- and postoperative computed tomography (CT) scans, and measurements of induced proptosis and implant volume were made. The proptosis induced by the implant averaged 2.2 mm and was stable over a 6-month period. Implant volume was constant throughout the study. Three-dimensional computer-generated images of the soft tissue, skeletal, and implant surfaces confirmed the implant stability. All animals were studied histologically with fluorochrome bone markers, which revealed minimal foreign body reaction to the implant, no evidence of infection, and marked fibrovascular ingrowth. We found the PFC/HA to possess properties that make it an ideal implant material: ease of availability, ease of handling, no resorption, minimal immunogenicity, infection resistance, no observed migration, biointegration, and no risk of disease transmission. PFC/HA may make an excellent implant material to manage orbital volume.

The Close Interaction of a C-F Bond with an Amide Carbonyl: Crystallographic and Spectroscopic Characterization

The putative interaction of a C-F bond with an amide carbonyl has been an intriguing topic of interest in this century for reasons spanning basic physical organic chemistry to biochemistry. However, to date, there exist no examples of a close, well-defined interaction in which its unique aspects can be identified and exploited. Herein, we finally present an engineered system possessing an exceptionally tight C-F-amide interaction, allowing us to obtain spectroscopic, crystallographic, and kinetic details of a distinctive, biochemically relevant chemical system for the first time. In turn, we also explore Lewis acid coordination, C-F bond promotion of amide isomerization, enantiomerization, and ion protonation processes.

Eyelid lipoid granuloma following topical ointment application

Subcutaneous lipogranulomas have been known to occur after injection of lipids for cosmetic or therapeutic reasons. Fibrosis may occur around the granulomas, giving them a lobulated appearance that can clinically mimic a malignancy. Of the few reports of lipogranulomas after the use of topical ointment, none have occurred in the eyelid. We report a case of subconjunctival lipogranulomas after the use of topical ointment whose clinical appearance was suggestive of sebaceous gland carcinoma.

Close Amide NH···F Hydrogen Bonding Interactions in 1,8-Disubstituted Naphthalenes

In this note, we present a series of N-(8-fluoronaphthalen-1-yl)benzamide derivatives designed to maximize amide-NH···F hydrogen bond interactions therein. A combination of IR and NMR spectroscopy indicates a linear correlation between the high energy shift in NH stretching frequency and the electron withdrawing nature of the substituent, consistent with the trend predicted by DFT calculations. Additionally, a limiting case of hydrogen bonding is observed when the benzamide derivatives are replaced with trifluoroacetamide, causing an additional red shift of 44 cm^-1 in the NH stretching frequency. Most importantly, ¹H-¹⁹F coupling constants in this series are among the largest measured for amide-NH···F interactions. X-ray crystallography reveals face-to-face alignment of naphthalene rings in these derivatives resulting in part from the NH···F hydrogen bonds. This motif also dictates the formation of sheets composed of stacked naphthalene rings in the crystal structure as opposed to unfluorinated analogues wherein NH···OC hydrogen-bonding interactions force benzamide and naphthalene rings to engage in T-shaped π-π interactions instead. Additionally, the NH proton in the trifluoroacetamide derivative engages in extended H-bond interactions in its crystal structure.

Endoscopy and biopsy of the orbit

Flexible endoscopes produce high-quality images, are small in size, and can deliver microsurgical instruments or laser probes. Early attempts at orbital endoscopy were limited by the relatively large size and poor visualization of rigid endoscopes. We performed endoscopic orbital exploration using the Olympus HYF flexible endoscope in four live dog orbits. We achieved excellent visualization of orbital structures including the globe, blood vessels, extraocular muscles, intermuscular septa, optic nerve, and fat. Visualization, hemostasis, and dissection were aided by the use of hyaluronic acid infused through the endoscope. We biopsied fat and extraocular muscle without complication using Olympus endoscopic cup biopsy forceps (confirmed by histopathologic examination). Our experience indicates that orbital endoscopy aided by viscoelastic hydrodissection may permit a less invasive approach to optic nerve sheath fenestration, tumor biopsy and treatment, and the removal of foreign bodies.

Switching a HO···π Interaction to a Nonconventional OH···π Hydrogen Bond: A Completed Crystallographic Puzzle

In this article, we present crystallographic and spectroscopic evidence of a tunable system wherein a HO···π interaction switches incrementally to a nonconventional OH···π hydrogen bonding (HB) interaction. More specifically, we report the synthesis of substituted forms of model system 1 to study the effects of aryl ring electronic density on the qualitative characteristics of OH···π hydrogen bonds therein. The OH stretch in experimental infrared data, in agreement with density-functional theory (DFT) calculations, shows continuous red-shifts as the adjacent ring becomes more electron rich. For example, the OH stretch of an amino-substituted analogue is red-shifted by roughly 50 cm^-1 compared to the same stretch in the CF₃ analogue, indicating a significantly stronger HB interaction in the former. Moreover, DFT calculations (ωB97XD/6-311+G**) predict that increasing electronic density on the adjacent top ring reduces the aryl π-OH σ* energy gap with a concomitant enhancement of the OH n-π* energy gap. Consequently, a dominant π-σ* interaction in the amino substituted analogue locks the system in the in-form while a favorable n-π* interaction reverses the orientation of the oxygen-bound hydrogen in its protonated form. Additionally, the ¹H NMR data of various analogues reveal that stronger OH···π interactions in systems with electron-rich aromatic rings slow exchange of the alcoholic proton, thereby revealing coupling with the geminal proton. Finally, X-ray crystallographic analyses of a spectrum of analogues clearly visualize the three distinct stages of "switch"-starting with exclusive HO···π, to partitioned HO···π/OH···π, and finally to achieving exclusive OH···π forms. Furthermore, the crystal structure of the amino analogue reveals an interesting feature in which an extended HB network, involving two conventional (NH···O) and two nonconventional (OH···π) HBs, dimerizes and anchors the molecule in the unit cell.

Absence of seasonal variation in Graves disease

PURPOSE

To determine whether there is an identifiable pattern of seasonal variation in the onset of symptoms of orbitopathy and thyrotoxicosis in patients with Graves disease.

METHODS

This retrospective, noncomparative case series reviewed 305 randomly selected office records of patients referred to one author (M.K.) for evaluation of Graves orbitopathy between July 1990 and June 1998. All patients met inclusion criteria for the diagnosis of Graves orbitopathy. During initial evaluation for orbitopathy, patients identified the date of onset of orbital symptoms as well as the earliest date of either onset of thyroid symptoms or documented thyroid abnormality. Patients were excluded from analysis of seasonal variation if they could not recall the month of symptom onset or were euthyroid. The onset of orbital symptoms and identification of dysthyroid state were analyzed by calendar month and season. The chronological relationship of the development of orbital and thyroid symptoms was evaluated.

RESULTS

No significant seasonal variation appeared in the onset of orbital symptoms or identification of dysthyroidism. Out of 148 patients, 115 (78%) developed symptoms of orbital disease within 18 months of the identification of dysthyroidism. The most common presenting orbital symptoms were swelling of the lid or prominence of the globe.

CONCLUSIONS

This study fails to provide evidence for a seasonal influence on the incidence of Graves disease and the associated orbitopathy.

Suitability changes of Citrus medica L. var. sarcodactylis Swingle, a medicine-food plants affected by climate warming using the optimized MaxEnt model

Climatic variables are important conditions for plant growth, development and reproduction. Citrus medica L. var. sarcodactylis Swingle (Rutaceae: Citrus) is one of the traditional bulk Chinese medicinal materials in China with the effects of bacteriostasis, anti-inflammatory, anti-oxidation, anti-cancer cells, regulating the immun. Analyzing the impact of climate change on geographical distribution of C. medica L. var. sarcodactylis can provide strong support for its production layout and agricultural zoning. In our paper, MaxEnt and ArcGIS were applied to simulate the suitable areas of C. medica L. var. sarcodactylis in China from the perspectives of bioclimate, soil, topographic factors and human activities, and the future climate scenarios generated by global climate models (GCMs) were selected to predict its suitable areas in 2050s and 2090s. Results showed that, 1) Under current climate condition, areas of the total, most, moderately and poorly suitable habitats of C. medica L. var. sarcodactylis in China were 177.36×104 km2, 22.27×104 km2, 51.96×104 km2 and 103.13×104 km2 respectively. The range of the most suitable habitat was the narrowest, which was located in the middle east of Sichuan, western Chongqing in the upstream of the Yangtze River Basin, southern Guizhou and western Guangxi in the upstream of the Pearl River Basin, central and southern Yunnan and Southeast Tibet in the Middle-Lower reaches of the Southwest River Basin and western Taiwan. 2) Under the future climate change scenarios, the total suitable area showed a significant increase trend in 2090s, and the change of most, moderately and poorly suitable habitats showed no obvious law. 3) Under SSP1-2.6, SSP2-4.5 and SSP5-8.5 scenarios, the centroid of the most suitable habitat of C. medica L. var. sarcodactylis would move to the northwest, southeast and southwest respectively.

Structural proof of a [C-F-C]+ fluoronium cation

Organic fluoronium ions can be described as positively charged molecules in which the most electronegative and least polarizable element fluorine engages in two partially covalent bonding interactions to two carbon centers. While recent solvolysis experiments and NMR spectroscopic studies on a metastable [C–F–C]⁺ fluoronium ion strongly support the divalent fluoronium structure over the alternative rapidly equilibrating classical carbocation, the model system has, to date, eluded crystallographic analysis to confirm this phenomenon in the solid state. Herein, we report the single crystal structure of a symmetrical [C–F–C]⁺ fluoronium cation. Besides its synthesis and crystallographic characterization as the [Sb₂F₁₁]⁻ salt, vibrational spectra are discussed and a detailed analysis concerning the nature of the bonding situation in this fluoronium ion and its heavier halonium homologues is performed, which provides detailed insights on this molecular structure.

Unlike other halogen atoms, the ability for fluorine to exist in a [C–X–C]⁺ connectivity pattern has only been shown in spectroscopic studies. Here the authors present a single crystal structure of a fluoronium cation, characterized by X-ray diffraction.

Correlation of serum immunoglobulin E elevations with clinical stages of dysthyroid orbitopathy

Total immunoglobulin E (IgE) was measured by an enzyme-linked immunoassay in serum samples from patients with dysthyroid orbitopathy and from a group of healthy volunteers. All the serum donors had no symptoms of allergy or infection and were not given any immunoregulative treatments for at least 6 months before the sampling. One hundred thirty-seven dysthyroid orbitopathy patients were rated clinically as belonging to one of the following groups: (1) stable dysthyroid orbitopathy; (2) active dysthyroid orbitopathy; (3) chronic or recurrent dysthyroid orbitopathy; or (4) dysthyroid orbitopathy characterized by limited myopathy. The serum IgE levels of all these groups were compared with 26 healthy, nonatopic volunteers. The mean IgE levels of groups 3 and 4 were significantly higher than the mean IgE level of the control group as well as that of the group with stable dysthyroid orbitopathy. Furthermore, serial readings on several patients were consistent with the hypothesis that serum IgE is elevated in connection with certain stages of rapid dysthyroid orbitopathy progression and also with two unusual clinical forms of dysthyroid orbitopathy.

Discovery and Mechanistic Study of a Totally Organic C(aryl)-C(alkyl)Oxygen Insertion Reaction

We report an unprecedented photochemical oxygen insertion reaction into an aromatic quinone methide. Insertion happens specifically within a C_(aryl)-C_(alkyl) bond, whereas the quinone methide moiety remains intact itself. Detailed mechanistic studies, supported by DFT calculations, support a pathway in which the p-QM plays a pivotal activating role.

Schizontocidal activity of antibiotics against blood-induced Plasmodium gallinaceum infection

Comparative studies on the blood schizontocidal activity of antibiotics against Plasmodium gallinaceum infection of chicks have shown that doxycycline, minocycline, demeclocycline, tetracycline and oxytetracycline possess high antimalarial activity as judged by suppression of parasitaemia and extension of survival period. Of these, demeclocycline, tetracycline and oxytetracycline were effective only at high dose level. Chloramphenicol, erythromycin and gentamicin were relatively inactive. Treatment in 5- to 6-day-old established infection of chicks has shown that doxycycline and minocycline are relatively more effective than oxytetracycline and tetracycline in controlling acute infection.

A Protonated Quinone Methide Stabilized by a Combination of Partial Aromatization and π-Interaction: Spectroscopic and Crystallographic Analysis

We have expanded the repertoire of cation-π interactions to include a carbocation-π system resulting from the protonation of a π-stacked para-quinone methide (p-QM). This unusual carbocation is stabilized by a combination of partial aromatization of the QM moiety and through-space interaction with the π-system of the adjacent aromatic ring. Single crystal X-ray analysis of the protonated form reveals a structure consisting of a hydrogen-bound complex involving two molecules of the precursor and one proton.